From 74bcb3e347888d7c6953cb7209caf783abf93c2a Mon Sep 17 00:00:00 2001
From: Stefan Probst <stefanprobst@kolabnow.com>
Date: Sun, 30 Dec 2018 21:53:30 +0100
Subject: [PATCH 01/20] Add serialization with v8

---
 packages/gatsby/src/redux/index.js | 54 +++++-------------------------
 1 file changed, 9 insertions(+), 45 deletions(-)

diff --git a/packages/gatsby/src/redux/index.js b/packages/gatsby/src/redux/index.js
index b503211d55a4b..755d1323cfc92 100644
--- a/packages/gatsby/src/redux/index.js
+++ b/packages/gatsby/src/redux/index.js
@@ -2,7 +2,7 @@ const Redux = require(`redux`)
 const _ = require(`lodash`)
 const fs = require(`fs`)
 const mitt = require(`mitt`)
-const stringify = require(`json-stringify-safe`)
+const v8 = require(`v8`)
 
 // Create event emitter for actions
 const emitter = mitt()
@@ -10,43 +10,17 @@ const emitter = mitt()
 // Reducers
 const reducers = require(`./reducers`)
 
-const objectToMap = obj => {
-  let map = new Map()
-  Object.keys(obj).forEach(key => {
-    map.set(key, obj[key])
-  })
-  return map
-}
+const readFileSync = file => v8.deserialize(fs.readFileSync(file))
 
-const mapToObject = map => {
-  const obj = {}
-  for (let [key, value] of map) {
-    obj[key] = value
-  }
-  return obj
-}
+const writeFileSync = (file, contents) =>
+  fs.writeFileSync(file, v8.serialize(contents))
+
+const file = `${process.cwd()}/.cache/redux-state.json`
 
-// Read from cache the old node data.
+// Read old node data from cache.
 let initialState = {}
 try {
-  const file = fs.readFileSync(`${process.cwd()}/.cache/redux-state.json`)
-  // Apparently the file mocking in node-tracking-test.js
-  // can override the file reading replacing the mocked string with
-  // an already parsed object.
-  if (Buffer.isBuffer(file) || typeof file === `string`) {
-    initialState = JSON.parse(file)
-  }
-  if (initialState.staticQueryComponents) {
-    initialState.staticQueryComponents = objectToMap(
-      initialState.staticQueryComponents
-    )
-  }
-  if (initialState.components) {
-    initialState.components = objectToMap(initialState.components)
-  }
-  if (initialState.nodes) {
-    initialState.nodes = objectToMap(initialState.nodes)
-  }
+  initialState = readFileSync(file)
 } catch (e) {
   // ignore errors.
 }
@@ -74,17 +48,7 @@ function saveState() {
     `staticQueryComponents`,
   ])
 
-  pickedState.staticQueryComponents = mapToObject(
-    pickedState.staticQueryComponents
-  )
-  pickedState.components = mapToObject(pickedState.components)
-  pickedState.nodes = pickedState.nodes ? mapToObject(pickedState.nodes) : []
-  const stringified = stringify(pickedState, null, 2)
-  fs.writeFile(
-    `${process.cwd()}/.cache/redux-state.json`,
-    stringified,
-    () => {}
-  )
+  writeFileSync(file, pickedState)
 }
 
 exports.saveState = saveState

From af7bdb14a07eaf4ee73fa69a8e589b9386b561aa Mon Sep 17 00:00:00 2001
From: Stefan Probst <stefanprobst@kolabnow.com>
Date: Sun, 30 Dec 2018 22:35:50 +0100
Subject: [PATCH 02/20] Change filename

---
 packages/gatsby/src/redux/index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/gatsby/src/redux/index.js b/packages/gatsby/src/redux/index.js
index 755d1323cfc92..1d13771158abc 100644
--- a/packages/gatsby/src/redux/index.js
+++ b/packages/gatsby/src/redux/index.js
@@ -15,7 +15,7 @@ const readFileSync = file => v8.deserialize(fs.readFileSync(file))
 const writeFileSync = (file, contents) =>
   fs.writeFileSync(file, v8.serialize(contents))
 
-const file = `${process.cwd()}/.cache/redux-state.json`
+const file = `${process.cwd()}/.cache/redux.state`
 
 // Read old node data from cache.
 let initialState = {}

From 04938eb6e51722b13086c8a1bcc443c0e440df8d Mon Sep 17 00:00:00 2001
From: Stefan Probst <stefanprobst@kolabnow.com>
Date: Wed, 2 Jan 2019 23:55:26 +0100
Subject: [PATCH 03/20] Add back json fallback

---
 packages/gatsby/src/redux/index.js | 41 ++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/packages/gatsby/src/redux/index.js b/packages/gatsby/src/redux/index.js
index 1d13771158abc..824f56ce1b077 100644
--- a/packages/gatsby/src/redux/index.js
+++ b/packages/gatsby/src/redux/index.js
@@ -3,6 +3,7 @@ const _ = require(`lodash`)
 const fs = require(`fs`)
 const mitt = require(`mitt`)
 const v8 = require(`v8`)
+const stringify = require(`json-stringify-safe`)
 
 // Create event emitter for actions
 const emitter = mitt()
@@ -10,10 +11,46 @@ const emitter = mitt()
 // Reducers
 const reducers = require(`./reducers`)
 
-const readFileSync = file => v8.deserialize(fs.readFileSync(file))
+const objectToMap = obj => {
+  const map = new Map()
+  Object.keys(obj).forEach(key => {
+    map.set(key, obj[key])
+  })
+  return map
+}
+
+const mapToObject = map => {
+  const obj = {}
+  for (let [key, value] of map) {
+    obj[key] = value
+  }
+  return obj
+}
+
+const jsonStringify = contents => {
+  contents.staticQueryComponents = mapToObject(contents.staticQueryComponents)
+  contents.components = mapToObject(contents.components)
+  contents.nodes = mapToObject(contents.nodes)
+  return stringify(contents, null, 2)
+}
+
+const jsonParse = buffer => {
+  const parsed = JSON.parse(buffer.toString(`utf8`))
+  parsed.staticQueryComponents = objectToMap(parsed.staticQueryComponents)
+  parsed.components = objectToMap(parsed.components)
+  parsed.nodes = objectToMap(parsed.nodes)
+  return parsed
+}
+
+const useV8 = Boolean(v8.serialize)
+const [serialize, deserialize] = useV8
+  ? [v8.serialize, v8.deserialize]
+  : [jsonStringify, jsonParse]
+
+const readFileSync = file => deserialize(fs.readFileSync(file))
 
 const writeFileSync = (file, contents) =>
-  fs.writeFileSync(file, v8.serialize(contents))
+  fs.writeFileSync(file, serialize(contents))
 
 const file = `${process.cwd()}/.cache/redux.state`
 

From 7c60f6c4ce0846c85d4e1cbab2d9c5b0368e4286 Mon Sep 17 00:00:00 2001
From: Stefan Probst <stefanprobst@kolabnow.com>
Date: Wed, 16 Jan 2019 00:38:57 +0100
Subject: [PATCH 04/20] Don't use non-serializeable function in pluginOptions

---
 examples/using-gatsby-image/gatsby-config.js                  | 2 +-
 .../plugins/gatsby-source-remote-images/gatsby-node.js        | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/examples/using-gatsby-image/gatsby-config.js b/examples/using-gatsby-image/gatsby-config.js
index 3324d3e993035..d7b4e8e710d5a 100644
--- a/examples/using-gatsby-image/gatsby-config.js
+++ b/examples/using-gatsby-image/gatsby-config.js
@@ -20,7 +20,7 @@ module.exports = {
     {
       resolve: `gatsby-source-remote-images`,
       options: {
-        filter: node => node.internal.type === `UnsplashImagesYaml`,
+        typeName: `UnsplashImagesYaml`,
       },
     },
   ],
diff --git a/examples/using-gatsby-image/plugins/gatsby-source-remote-images/gatsby-node.js b/examples/using-gatsby-image/plugins/gatsby-source-remote-images/gatsby-node.js
index 5b5a86be28eed..59f72f2626065 100644
--- a/examples/using-gatsby-image/plugins/gatsby-source-remote-images/gatsby-node.js
+++ b/examples/using-gatsby-image/plugins/gatsby-source-remote-images/gatsby-node.js
@@ -2,9 +2,9 @@ const { createRemoteFileNode } = require(`gatsby-source-filesystem`)
 
 exports.onCreateNode = async (
   { actions: { createNode }, node, createContentDigest, store, cache },
-  { filter, nodeName = `localFile` }
+  { typeName, nodeName = `localFile` }
 ) => {
-  if (filter(node)) {
+  if (node.internal.type === typeName) {
     const fileNode = await createRemoteFileNode({
       url: node.url,
       store,

From 2cc2036dec37ed6ea922bee1aec36c01e82031d7 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Thu, 21 Mar 2019 20:03:01 +0100
Subject: [PATCH 05/20] revert plugin changes

---
 examples/using-gatsby-image/gatsby-config.js                  | 2 +-
 .../plugins/gatsby-source-remote-images/gatsby-node.js        | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/examples/using-gatsby-image/gatsby-config.js b/examples/using-gatsby-image/gatsby-config.js
index d7b4e8e710d5a..3324d3e993035 100644
--- a/examples/using-gatsby-image/gatsby-config.js
+++ b/examples/using-gatsby-image/gatsby-config.js
@@ -20,7 +20,7 @@ module.exports = {
     {
       resolve: `gatsby-source-remote-images`,
       options: {
-        typeName: `UnsplashImagesYaml`,
+        filter: node => node.internal.type === `UnsplashImagesYaml`,
       },
     },
   ],
diff --git a/examples/using-gatsby-image/plugins/gatsby-source-remote-images/gatsby-node.js b/examples/using-gatsby-image/plugins/gatsby-source-remote-images/gatsby-node.js
index 59f72f2626065..5b5a86be28eed 100644
--- a/examples/using-gatsby-image/plugins/gatsby-source-remote-images/gatsby-node.js
+++ b/examples/using-gatsby-image/plugins/gatsby-source-remote-images/gatsby-node.js
@@ -2,9 +2,9 @@ const { createRemoteFileNode } = require(`gatsby-source-filesystem`)
 
 exports.onCreateNode = async (
   { actions: { createNode }, node, createContentDigest, store, cache },
-  { typeName, nodeName = `localFile` }
+  { filter, nodeName = `localFile` }
 ) => {
-  if (node.internal.type === typeName) {
+  if (filter(node)) {
     const fileNode = await createRemoteFileNode({
       url: node.url,
       store,

From b87c8dfb04cd8ffeb05631a585cc03b96976fbf3 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Thu, 21 Mar 2019 20:03:39 +0100
Subject: [PATCH 06/20] remove pluginOptions from `sitePlugin` node - this
 cause trouble with inferring anyway

---
 .../src/internal-plugins/internal-data-bridge/gatsby-node.js    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/gatsby/src/internal-plugins/internal-data-bridge/gatsby-node.js b/packages/gatsby/src/internal-plugins/internal-data-bridge/gatsby-node.js
index 7f134cebffd7c..22d1da5e40188 100644
--- a/packages/gatsby/src/internal-plugins/internal-data-bridge/gatsby-node.js
+++ b/packages/gatsby/src/internal-plugins/internal-data-bridge/gatsby-node.js
@@ -61,7 +61,7 @@ exports.sourceNodes = ({ createContentDigest, actions, store }) => {
     },
   })
 
-  flattenedPlugins.forEach(plugin => {
+  flattenedPlugins.forEach(({ pluginOptions, ...plugin }) => {
     plugin.pluginFilepath = plugin.resolve
     createNode({
       ...plugin,

From 62a991ce7b60340255b2af0c33c5f96ee1572bf7 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Thu, 21 Mar 2019 20:16:15 +0100
Subject: [PATCH 07/20] keep `redux-state.json` path for json-stringify

---
 packages/gatsby/src/redux/index.js | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/packages/gatsby/src/redux/index.js b/packages/gatsby/src/redux/index.js
index 4357586181d21..42f029769ca4a 100644
--- a/packages/gatsby/src/redux/index.js
+++ b/packages/gatsby/src/redux/index.js
@@ -43,16 +43,15 @@ const jsonParse = buffer => {
 }
 
 const useV8 = Boolean(v8.serialize)
-const [serialize, deserialize] = useV8
-  ? [v8.serialize, v8.deserialize]
-  : [jsonStringify, jsonParse]
+const [serialize, deserialize, file] = useV8
+  ? [v8.serialize, v8.deserialize, `${process.cwd()}/.cache/redux.state`]
+  : [jsonStringify, jsonParse, `${process.cwd()}/.cache/redux-state.json`]
 
 const readFileSync = file => deserialize(fs.readFileSync(file))
 
-const writeFileSync = (file, contents) =>
+const writeFileSync = (file, contents) => {
   fs.writeFileSync(file, serialize(contents))
-
-const file = `${process.cwd()}/.cache/redux.state`
+}
 
 // Read old node data from cache.
 let initialState = {}

From 82099dfbe7ff468fabfc542b6bd52fde24bec758 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Sat, 30 Mar 2019 19:47:07 +0100
Subject: [PATCH 08/20] sanitize node data

---
 packages/gatsby/src/db/node-tracking.js | 26 +++++++++++++++++++++----
 packages/gatsby/src/redux/actions.js    |  2 +-
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/packages/gatsby/src/db/node-tracking.js b/packages/gatsby/src/db/node-tracking.js
index b344a6266136c..569f972d696ae 100644
--- a/packages/gatsby/src/db/node-tracking.js
+++ b/packages/gatsby/src/db/node-tracking.js
@@ -16,10 +16,28 @@ const getRootNodeId = node => rootNodeMap.get(node)
  * @param {(Object|Array)} data Inline object or array
  * @param {string} nodeId Id of node that contains data passed in first parameter
  */
-const addRootNodeToInlineObject = (data, nodeId) => {
+const addRootNodeToInlineObject = (data, nodeId, sanitize, parent, key) => {
   if (_.isPlainObject(data) || _.isArray(data)) {
-    _.each(data, o => addRootNodeToInlineObject(o, nodeId))
+    _.each(data, (o, key) => {
+      addRootNodeToInlineObject(o, nodeId, sanitize, key, data)
+    })
     rootNodeMap.set(data, nodeId)
+
+    // arrays and plain objects are supported - no need to to sanitize
+    return
+  }
+
+  if (sanitize) {
+    const type = typeof data
+    // supported types
+    const isSupported =
+      type === `number` ||
+      type === `string` ||
+      type === `boolean` ||
+      data instanceof Date
+    if (!isSupported) {
+      delete parent[key]
+    }
   }
 }
 
@@ -28,13 +46,13 @@ const addRootNodeToInlineObject = (data, nodeId) => {
  * and that Node object.
  * @param {Node} node Root Node
  */
-const trackInlineObjectsInRootNode = node => {
+const trackInlineObjectsInRootNode = (node, sanitize = false) => {
   _.each(node, (v, k) => {
     // Ignore the node internal object.
     if (k === `internal`) {
       return
     }
-    addRootNodeToInlineObject(v, node.id)
+    addRootNodeToInlineObject(v, node.id, sanitize, node, k)
   })
 
   return node
diff --git a/packages/gatsby/src/redux/actions.js b/packages/gatsby/src/redux/actions.js
index 5db90337089fb..45f1486d00a37 100644
--- a/packages/gatsby/src/redux/actions.js
+++ b/packages/gatsby/src/redux/actions.js
@@ -591,7 +591,7 @@ actions.createNode = (
     )
   }
 
-  trackInlineObjectsInRootNode(node)
+  trackInlineObjectsInRootNode(node, true)
 
   const oldNode = getNode(node.id)
 

From db6740f834a8db98ba209273a2eb9167d91a8bd8 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Sat, 30 Mar 2019 20:14:20 +0100
Subject: [PATCH 09/20] Revert "remove pluginOptions from `sitePlugin` node -
 this cause trouble with inferring anyway"

This reverts commit b87c8dfb04cd8ffeb05631a585cc03b96976fbf3.
---
 .../src/internal-plugins/internal-data-bridge/gatsby-node.js    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/gatsby/src/internal-plugins/internal-data-bridge/gatsby-node.js b/packages/gatsby/src/internal-plugins/internal-data-bridge/gatsby-node.js
index 22d1da5e40188..7f134cebffd7c 100644
--- a/packages/gatsby/src/internal-plugins/internal-data-bridge/gatsby-node.js
+++ b/packages/gatsby/src/internal-plugins/internal-data-bridge/gatsby-node.js
@@ -61,7 +61,7 @@ exports.sourceNodes = ({ createContentDigest, actions, store }) => {
     },
   })
 
-  flattenedPlugins.forEach(({ pluginOptions, ...plugin }) => {
+  flattenedPlugins.forEach(plugin => {
     plugin.pluginFilepath = plugin.resolve
     createNode({
       ...plugin,

From 6d3acc53ae5bfd32b8acdc15e11b90076fd7ff00 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Fri, 5 Apr 2019 20:10:41 +0200
Subject: [PATCH 10/20] sanitize nodes

---
 .../__snapshots__/node-tracking-test.js.snap  | 22 ++++++
 .../src/db/__tests__/node-tracking-test.js    | 72 ++++++++++++++++++-
 packages/gatsby/src/db/node-tracking.js       | 62 +++++++++++-----
 packages/gatsby/src/redux/actions.js          |  2 +-
 4 files changed, 138 insertions(+), 20 deletions(-)
 create mode 100644 packages/gatsby/src/db/__tests__/__snapshots__/node-tracking-test.js.snap

diff --git a/packages/gatsby/src/db/__tests__/__snapshots__/node-tracking-test.js.snap b/packages/gatsby/src/db/__tests__/__snapshots__/node-tracking-test.js.snap
new file mode 100644
index 0000000000000..e397a70cb812c
--- /dev/null
+++ b/packages/gatsby/src/db/__tests__/__snapshots__/node-tracking-test.js.snap
@@ -0,0 +1,22 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`track root nodes Node sanitization Remove not supported fields / values 1`] = `
+Object {
+  "children": Array [],
+  "id": "id1",
+  "inlineArray": Array [
+    1,
+    2,
+    3,
+  ],
+  "inlineObject": Object {
+    "field": "fieldOfFirstNode",
+  },
+  "internal": Object {
+    "contentDigest": "digest1",
+    "owner": "test",
+    "type": "Test",
+  },
+  "parent": null,
+}
+`;
diff --git a/packages/gatsby/src/db/__tests__/node-tracking-test.js b/packages/gatsby/src/db/__tests__/node-tracking-test.js
index c627eabc499fc..8143f5f1ca10c 100644
--- a/packages/gatsby/src/db/__tests__/node-tracking-test.js
+++ b/packages/gatsby/src/db/__tests__/node-tracking-test.js
@@ -3,7 +3,11 @@ const {
   boundActionCreators: { createNode },
 } = require(`../../redux/actions`)
 const { getNode } = require(`../../db/nodes`)
-const { findRootNodeAncestor, trackDbNodes } = require(`../node-tracking`)
+const {
+  findRootNodeAncestor,
+  trackDbNodes,
+  trackInlineObjectsInRootNode,
+} = require(`../node-tracking`)
 const { run: runQuery } = require(`../nodes-query`)
 require(`./fixtures/ensure-loki`)()
 
@@ -136,4 +140,70 @@ describe(`track root nodes`, () => {
       expect(findRootNodeAncestor(result[0].inlineObject)).toEqual(result[0])
     })
   })
+
+  describe(`Node sanitization`, () => {
+    let testNode
+    beforeEach(() => {
+      testNode = {
+        id: `id1`,
+        parent: null,
+        children: [],
+        unsupported: () => {},
+        inlineObject: {
+          field: `fieldOfFirstNode`,
+          re: /re/,
+        },
+        inlineArray: [1, 2, 3, Symbol(`test`)],
+        internal: {
+          type: `Test`,
+          contentDigest: `digest1`,
+          owner: `test`,
+        },
+      }
+    })
+
+    it(`Remove not supported fields / values`, () => {
+      const result = trackInlineObjectsInRootNode(testNode, true)
+      expect(result).toMatchSnapshot()
+      expect(result.unsupported).not.toBeDefined()
+      expect(result.inlineObject.re).not.toBeDefined()
+      expect(result.inlineArray[3]).not.toBeDefined()
+    })
+
+    it(`Doesn't mutate original`, () => {
+      trackInlineObjectsInRootNode(testNode, true)
+      expect(testNode.unsupported).toBeDefined()
+      expect(testNode.inlineObject.re).toBeDefined()
+      expect(testNode.inlineArray[3]).toBeDefined()
+    })
+
+    it(`Create copy of node if it has to remove anything`, () => {
+      const result = trackInlineObjectsInRootNode(testNode, true)
+      expect(result).not.toBe(testNode)
+    })
+
+    it(`Doesn't create clones if it doesn't have to`, () => {
+      const testNodeWithoutUnserializableData = {
+        id: `id1`,
+        parent: null,
+        children: [],
+        inlineObject: {
+          field: `fieldOfFirstNode`,
+        },
+        inlineArray: [1, 2, 3],
+        internal: {
+          type: `Test`,
+          contentDigest: `digest1`,
+          owner: `test`,
+        },
+      }
+
+      const result = trackInlineObjectsInRootNode(
+        testNodeWithoutUnserializableData,
+        true
+      )
+      // should be same instance
+      expect(result).toBe(testNodeWithoutUnserializableData)
+    })
+  })
 })
diff --git a/packages/gatsby/src/db/node-tracking.js b/packages/gatsby/src/db/node-tracking.js
index 569f972d696ae..cabfa277fc57e 100644
--- a/packages/gatsby/src/db/node-tracking.js
+++ b/packages/gatsby/src/db/node-tracking.js
@@ -15,30 +15,65 @@ const getRootNodeId = node => rootNodeMap.get(node)
  * @see trackInlineObjectsInRootNode
  * @param {(Object|Array)} data Inline object or array
  * @param {string} nodeId Id of node that contains data passed in first parameter
+ * @param {boolean} sanitize Wether to strip objects of unuspported and not serializable fields
+ * @param {string} [ignore] Fieldname that doesn't need to be tracked and sanitized
+ *
  */
-const addRootNodeToInlineObject = (data, nodeId, sanitize, parent, key) => {
-  if (_.isPlainObject(data) || _.isArray(data)) {
+const addRootNodeToInlineObject = (data, nodeId, sanitize, ignore = null) => {
+  const isPlainObject = _.isPlainObject(data)
+
+  if (isPlainObject || _.isArray(data)) {
+    let returnData = data
+    if (sanitize) {
+      returnData = isPlainObject ? {} : []
+    }
+    let anyFieldChanged = false
     _.each(data, (o, key) => {
-      addRootNodeToInlineObject(o, nodeId, sanitize, key, data)
+      if (ignore == key) {
+        returnData[key] = o
+        return
+      }
+      returnData[key] = addRootNodeToInlineObject(
+        o,
+        nodeId,
+        sanitize,
+        null,
+        key
+      )
+
+      if (returnData[key] !== o) {
+        anyFieldChanged = true
+      }
     })
+
+    if (anyFieldChanged) {
+      if (isPlainObject) {
+        data = _.pickBy(returnData, p => p !== undefined)
+      } else {
+        data = returnData.filter(p => p !== undefined)
+      }
+    }
+
     rootNodeMap.set(data, nodeId)
 
     // arrays and plain objects are supported - no need to to sanitize
-    return
+    return data
   }
 
-  if (sanitize) {
+  if (sanitize && data !== null) {
     const type = typeof data
-    // supported types
     const isSupported =
       type === `number` ||
       type === `string` ||
       type === `boolean` ||
       data instanceof Date
+
     if (!isSupported) {
-      delete parent[key]
+      return undefined
     }
   }
+  // either supported or not sanitizing
+  return data
 }
 
 /**
@@ -46,17 +81,8 @@ const addRootNodeToInlineObject = (data, nodeId, sanitize, parent, key) => {
  * and that Node object.
  * @param {Node} node Root Node
  */
-const trackInlineObjectsInRootNode = (node, sanitize = false) => {
-  _.each(node, (v, k) => {
-    // Ignore the node internal object.
-    if (k === `internal`) {
-      return
-    }
-    addRootNodeToInlineObject(v, node.id, sanitize, node, k)
-  })
-
-  return node
-}
+const trackInlineObjectsInRootNode = (node, sanitize = false) =>
+  addRootNodeToInlineObject(node, node.id, sanitize, `internal`)
 exports.trackInlineObjectsInRootNode = trackInlineObjectsInRootNode
 
 /**
diff --git a/packages/gatsby/src/redux/actions.js b/packages/gatsby/src/redux/actions.js
index 45f1486d00a37..cd235cb7a0986 100644
--- a/packages/gatsby/src/redux/actions.js
+++ b/packages/gatsby/src/redux/actions.js
@@ -591,7 +591,7 @@ actions.createNode = (
     )
   }
 
-  trackInlineObjectsInRootNode(node, true)
+  node = trackInlineObjectsInRootNode(node, true)
 
   const oldNode = getNode(node.id)
 

From 35c84e9480bd1f6727c062c807176603a35c6a35 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Fri, 5 Apr 2019 21:14:04 +0200
Subject: [PATCH 11/20] split redux persistance into separate file and adjust
 tests

---
 packages/gatsby/src/redux/__tests__/index.js | 13 ++---
 packages/gatsby/src/redux/index.js           | 51 ++------------------
 packages/gatsby/src/redux/persist.js         | 47 ++++++++++++++++++
 3 files changed, 56 insertions(+), 55 deletions(-)
 create mode 100644 packages/gatsby/src/redux/persist.js

diff --git a/packages/gatsby/src/redux/__tests__/index.js b/packages/gatsby/src/redux/__tests__/index.js
index 9581cf4780001..5c461a7dbdd6d 100644
--- a/packages/gatsby/src/redux/__tests__/index.js
+++ b/packages/gatsby/src/redux/__tests__/index.js
@@ -1,11 +1,11 @@
 const path = require(`path`)
-const fs = require(`fs-extra`)
 const { saveState, store } = require(`../index`)
+const { writeToCache } = require(`../persist`)
 const {
   actions: { createPage },
 } = require(`../actions`)
 
-jest.mock(`fs-extra`)
+jest.mock(`../persist`)
 
 describe(`redux db`, () => {
   beforeEach(() => {
@@ -24,15 +24,12 @@ describe(`redux db`, () => {
       )
     )
 
-    fs.writeFile.mockClear()
+    writeToCache.mockClear()
   })
   it(`should write cache to disk`, async () => {
     await saveState()
 
-    expect(fs.writeFile).toBeCalledWith(
-      expect.stringContaining(`.cache/redux-state.json`),
-      expect.stringContaining(`my-sweet-new-page.js`)
-    )
+    expect(writeToCache).toBeCalled()
   })
 
   it(`does not write to the cache when DANGEROUSLY_DISABLE_OOM is set`, async () => {
@@ -40,7 +37,7 @@ describe(`redux db`, () => {
 
     await saveState()
 
-    expect(fs.writeFile).not.toBeCalled()
+    expect(writeToCache).not.toBeCalled()
 
     delete process.env.DANGEROUSLY_DISABLE_OOM
   })
diff --git a/packages/gatsby/src/redux/index.js b/packages/gatsby/src/redux/index.js
index c92722f55dec6..ef0dade16de01 100644
--- a/packages/gatsby/src/redux/index.js
+++ b/packages/gatsby/src/redux/index.js
@@ -1,62 +1,19 @@
 const Redux = require(`redux`)
 const _ = require(`lodash`)
-const fs = require(`fs-extra`)
+
 const mitt = require(`mitt`)
-const v8 = require(`v8`)
-const stringify = require(`json-stringify-safe`)
 
 // Create event emitter for actions
 const emitter = mitt()
 
 // Reducers
 const reducers = require(`./reducers`)
-
-const objectToMap = obj => {
-  const map = new Map()
-  Object.keys(obj).forEach(key => {
-    map.set(key, obj[key])
-  })
-  return map
-}
-
-const mapToObject = map => {
-  const obj = {}
-  for (let [key, value] of map) {
-    obj[key] = value
-  }
-  return obj
-}
-
-const jsonStringify = contents => {
-  contents.staticQueryComponents = mapToObject(contents.staticQueryComponents)
-  contents.components = mapToObject(contents.components)
-  contents.nodes = mapToObject(contents.nodes)
-  return stringify(contents, null, 2)
-}
-
-const jsonParse = buffer => {
-  const parsed = JSON.parse(buffer.toString(`utf8`))
-  parsed.staticQueryComponents = objectToMap(parsed.staticQueryComponents)
-  parsed.components = objectToMap(parsed.components)
-  parsed.nodes = objectToMap(parsed.nodes)
-  return parsed
-}
-
-const useV8 = Boolean(v8.serialize)
-const [serialize, deserialize, file] = useV8
-  ? [v8.serialize, v8.deserialize, `${process.cwd()}/.cache/redux.state`]
-  : [jsonStringify, jsonParse, `${process.cwd()}/.cache/redux-state.json`]
-
-const readFileSync = file => deserialize(fs.readFileSync(file))
-
-const writeFileSync = (file, contents) => {
-  fs.writeFileSync(file, serialize(contents))
-}
+const { writeToCache, readFromCache } = require(`./persist`)
 
 // Read old node data from cache.
 let initialState = {}
 try {
-  initialState = readFileSync(file)
+  initialState = readFromCache()
   if (initialState.nodes) {
     // re-create nodesByType
     initialState.nodesByType = new Map()
@@ -99,7 +56,7 @@ function saveState() {
     `staticQueryComponents`,
   ])
 
-  writeFileSync(file, pickedState)
+  return writeToCache(pickedState)
 }
 
 exports.saveState = saveState
diff --git a/packages/gatsby/src/redux/persist.js b/packages/gatsby/src/redux/persist.js
new file mode 100644
index 0000000000000..fcbe48836f42c
--- /dev/null
+++ b/packages/gatsby/src/redux/persist.js
@@ -0,0 +1,47 @@
+const v8 = require(`v8`)
+const fs = require(`fs-extra`)
+const stringify = require(`json-stringify-safe`)
+
+const objectToMap = obj => {
+  const map = new Map()
+  Object.keys(obj).forEach(key => {
+    map.set(key, obj[key])
+  })
+  return map
+}
+
+const mapToObject = map => {
+  const obj = {}
+  for (let [key, value] of map) {
+    obj[key] = value
+  }
+  return obj
+}
+
+const jsonStringify = contents => {
+  contents.staticQueryComponents = mapToObject(contents.staticQueryComponents)
+  contents.components = mapToObject(contents.components)
+  contents.nodes = mapToObject(contents.nodes)
+  return stringify(contents, null, 2)
+}
+
+const jsonParse = buffer => {
+  const parsed = JSON.parse(buffer.toString(`utf8`))
+  parsed.staticQueryComponents = objectToMap(parsed.staticQueryComponents)
+  parsed.components = objectToMap(parsed.components)
+  parsed.nodes = objectToMap(parsed.nodes)
+  return parsed
+}
+
+const useV8 = Boolean(v8.serialize)
+const [serialize, deserialize, file] = useV8
+  ? [v8.serialize, v8.deserialize, `${process.cwd()}/.cache/redux.state`]
+  : [jsonStringify, jsonParse, `${process.cwd()}/.cache/redux-state.json`]
+
+const readFromCache = () => deserialize(fs.readFileSync(file))
+
+const writeToCache = contents => {
+  fs.writeFileSync(file, serialize(contents))
+}
+
+module.exports = { readFromCache, writeToCache }

From fba9b53ea2dc4764cb0c79cbeab9b85a5da2b2b2 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Fri, 5 Apr 2019 21:47:25 +0200
Subject: [PATCH 12/20] some more persisting tests confidence

---
 .../__tests__/__snapshots__/index.js.snap     | 27 +++++++++++++
 packages/gatsby/src/redux/__tests__/index.js  | 39 +++++++++++++++++--
 packages/gatsby/src/redux/index.js            | 34 +++++++++-------
 3 files changed, 83 insertions(+), 17 deletions(-)
 create mode 100644 packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap

diff --git a/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap b/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap
new file mode 100644
index 0000000000000..869fcec154b9c
--- /dev/null
+++ b/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap
@@ -0,0 +1,27 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`redux db should write cache to disk 1`] = `
+Object {
+  "componentDataDependencies": Object {
+    "connections": Object {},
+    "nodes": Object {},
+  },
+  "components": Map {
+    "<PROJECT_ROOT>/src/templates/my-sweet-new-page.js" => Object {
+      "componentPath": "<PROJECT_ROOT>/src/templates/my-sweet-new-page.js",
+      "isInBootstrap": true,
+      "pages": Array [
+        "/my-sweet-new-page/",
+      ],
+      "query": "",
+    },
+  },
+  "jsonDataPaths": Object {},
+  "nodes": Map {},
+  "nodesByType": Map {},
+  "staticQueryComponents": Map {},
+  "status": Object {
+    "plugins": Object {},
+  },
+}
+`;
diff --git a/packages/gatsby/src/redux/__tests__/index.js b/packages/gatsby/src/redux/__tests__/index.js
index 5c461a7dbdd6d..dec05b9b7055a 100644
--- a/packages/gatsby/src/redux/__tests__/index.js
+++ b/packages/gatsby/src/redux/__tests__/index.js
@@ -1,13 +1,26 @@
 const path = require(`path`)
-const { saveState, store } = require(`../index`)
-const { writeToCache } = require(`../persist`)
+const _ = require(`lodash`)
+jest.mock(`fs-extra`)
+const writeToCache = jest.spyOn(require(`../persist`), `writeToCache`)
+const { saveState, store, readState } = require(`../index`)
+
 const {
   actions: { createPage },
 } = require(`../actions`)
 
-jest.mock(`../persist`)
+const mockWrittenContent = new Map()
+jest.mock(`fs-extra`, () => {
+  return {
+    writeFileSync: jest.fn((file, content) =>
+      mockWrittenContent.set(file, content)
+    ),
+    readFileSync: jest.fn(file => mockWrittenContent.get(file)),
+  }
+})
 
 describe(`redux db`, () => {
+  const initialComponentsState = _.cloneDeep(store.getState().components)
+
   beforeEach(() => {
     store.dispatch(
       createPage(
@@ -25,11 +38,31 @@ describe(`redux db`, () => {
     )
 
     writeToCache.mockClear()
+    mockWrittenContent.clear()
+  })
+
+  it(`expect components state to be empty initially`, () => {
+    expect(initialComponentsState).toEqual(new Map())
   })
+
   it(`should write cache to disk`, async () => {
     await saveState()
 
     expect(writeToCache).toBeCalled()
+
+    // reset state in memory
+    store.dispatch({
+      type: `DELETE_CACHE`,
+    })
+    // make sure store in memory is empty
+    expect(store.getState().components).toEqual(initialComponentsState)
+
+    // read data that was previously cached
+    const data = readState()
+
+    // make sure data was read and is not the same as our clean redux state
+    expect(data.components).not.toEqual(initialComponentsState)
+    expect(data).toMatchSnapshot()
   })
 
   it(`does not write to the cache when DANGEROUSLY_DISABLE_OOM is set`, async () => {
diff --git a/packages/gatsby/src/redux/index.js b/packages/gatsby/src/redux/index.js
index ef0dade16de01..f5e90a24115e8 100644
--- a/packages/gatsby/src/redux/index.js
+++ b/packages/gatsby/src/redux/index.js
@@ -12,22 +12,28 @@ const { writeToCache, readFromCache } = require(`./persist`)
 
 // Read old node data from cache.
 let initialState = {}
-try {
-  initialState = readFromCache()
-  if (initialState.nodes) {
-    // re-create nodesByType
-    initialState.nodesByType = new Map()
-    initialState.nodes.forEach(node => {
-      const { type } = node.internal
-      if (!initialState.nodesByType.has(type)) {
-        initialState.nodesByType.set(type, new Map())
-      }
-      initialState.nodesByType.get(type).set(node.id, node)
-    })
+const readState = () => {
+  try {
+    initialState = readFromCache()
+    if (initialState.nodes) {
+      // re-create nodesByType
+      initialState.nodesByType = new Map()
+      initialState.nodes.forEach(node => {
+        const { type } = node.internal
+        if (!initialState.nodesByType.has(type)) {
+          initialState.nodesByType.set(type, new Map())
+        }
+        initialState.nodesByType.get(type).set(node.id, node)
+      })
+    }
+  } catch (e) {
+    // ignore errors.
+    initialState = {}
   }
-} catch (e) {
-  // ignore errors.
+  return initialState
 }
+readState()
+exports.readState = readState
 
 const store = Redux.createStore(
   Redux.combineReducers({ ...reducers }),

From 45f654c293350d41b30957b7be44e7047e4f9784 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Fri, 5 Apr 2019 22:13:08 +0200
Subject: [PATCH 13/20] don't track itself

---
 packages/gatsby/src/db/node-tracking.js | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/packages/gatsby/src/db/node-tracking.js b/packages/gatsby/src/db/node-tracking.js
index cabfa277fc57e..d93db5d603669 100644
--- a/packages/gatsby/src/db/node-tracking.js
+++ b/packages/gatsby/src/db/node-tracking.js
@@ -19,7 +19,7 @@ const getRootNodeId = node => rootNodeMap.get(node)
  * @param {string} [ignore] Fieldname that doesn't need to be tracked and sanitized
  *
  */
-const addRootNodeToInlineObject = (data, nodeId, sanitize, ignore = null) => {
+const addRootNodeToInlineObject = (data, nodeId, sanitize, isNode = false) => {
   const isPlainObject = _.isPlainObject(data)
 
   if (isPlainObject || _.isArray(data)) {
@@ -29,17 +29,11 @@ const addRootNodeToInlineObject = (data, nodeId, sanitize, ignore = null) => {
     }
     let anyFieldChanged = false
     _.each(data, (o, key) => {
-      if (ignore == key) {
+      if (isNode && key === `internal`) {
         returnData[key] = o
         return
       }
-      returnData[key] = addRootNodeToInlineObject(
-        o,
-        nodeId,
-        sanitize,
-        null,
-        key
-      )
+      returnData[key] = addRootNodeToInlineObject(o, nodeId, sanitize)
 
       if (returnData[key] !== o) {
         anyFieldChanged = true
@@ -54,7 +48,10 @@ const addRootNodeToInlineObject = (data, nodeId, sanitize, ignore = null) => {
       }
     }
 
-    rootNodeMap.set(data, nodeId)
+    // don't need to track node itself
+    if (!isNode) {
+      rootNodeMap.set(data, nodeId)
+    }
 
     // arrays and plain objects are supported - no need to to sanitize
     return data
@@ -82,7 +79,7 @@ const addRootNodeToInlineObject = (data, nodeId, sanitize, ignore = null) => {
  * @param {Node} node Root Node
  */
 const trackInlineObjectsInRootNode = (node, sanitize = false) =>
-  addRootNodeToInlineObject(node, node.id, sanitize, `internal`)
+  addRootNodeToInlineObject(node, node.id, sanitize, true)
 exports.trackInlineObjectsInRootNode = trackInlineObjectsInRootNode
 
 /**

From 1c20610ee44778e6058fe89f103698e7db59e6b0 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Fri, 5 Apr 2019 22:53:04 +0200
Subject: [PATCH 14/20] will this work on windows?

---
 .../gatsby/src/redux/__tests__/__snapshots__/index.js.snap | 4 ++--
 packages/gatsby/src/redux/__tests__/index.js               | 7 ++++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap b/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap
index 869fcec154b9c..ba105b6c2f4ac 100644
--- a/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap
+++ b/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap
@@ -7,8 +7,8 @@ Object {
     "nodes": Object {},
   },
   "components": Map {
-    "<PROJECT_ROOT>/src/templates/my-sweet-new-page.js" => Object {
-      "componentPath": "<PROJECT_ROOT>/src/templates/my-sweet-new-page.js",
+    "/Users/username/dev/site/src/templates/my-sweet-new-page.js" => Object {
+      "componentPath": "/Users/username/dev/site/src/templates/my-sweet-new-page.js",
       "isInBootstrap": true,
       "pages": Array [
         "/my-sweet-new-page/",
diff --git a/packages/gatsby/src/redux/__tests__/index.js b/packages/gatsby/src/redux/__tests__/index.js
index dec05b9b7055a..08a0dcc5cef6d 100644
--- a/packages/gatsby/src/redux/__tests__/index.js
+++ b/packages/gatsby/src/redux/__tests__/index.js
@@ -1,6 +1,6 @@
-const path = require(`path`)
+// const path = require(`path`)
 const _ = require(`lodash`)
-jest.mock(`fs-extra`)
+
 const writeToCache = jest.spyOn(require(`../persist`), `writeToCache`)
 const { saveState, store, readState } = require(`../index`)
 
@@ -26,7 +26,8 @@ describe(`redux db`, () => {
       createPage(
         {
           path: `/my-sweet-new-page/`,
-          component: path.resolve(`./src/templates/my-sweet-new-page.js`),
+          // seems like jest serializer doesn't play nice with Maps on Windows
+          component: `/Users/username/dev/site/src/templates/my-sweet-new-page.js`,
           // The context is passed as props to the component as well
           // as into the component's GraphQL query.
           context: {

From 0d9bf437307dba741dad3040d8c43c3fb9fea73e Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Sat, 6 Apr 2019 00:50:47 +0200
Subject: [PATCH 15/20] oh loki

---
 .../gatsby/src/redux/__tests__/__snapshots__/index.js.snap    | 2 --
 packages/gatsby/src/redux/__tests__/index.js                  | 4 +++-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap b/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap
index ba105b6c2f4ac..14658aae15f86 100644
--- a/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap
+++ b/packages/gatsby/src/redux/__tests__/__snapshots__/index.js.snap
@@ -17,8 +17,6 @@ Object {
     },
   },
   "jsonDataPaths": Object {},
-  "nodes": Map {},
-  "nodesByType": Map {},
   "staticQueryComponents": Map {},
   "status": Object {
     "plugins": Object {},
diff --git a/packages/gatsby/src/redux/__tests__/index.js b/packages/gatsby/src/redux/__tests__/index.js
index 08a0dcc5cef6d..407b4fc7f3162 100644
--- a/packages/gatsby/src/redux/__tests__/index.js
+++ b/packages/gatsby/src/redux/__tests__/index.js
@@ -63,7 +63,9 @@ describe(`redux db`, () => {
 
     // make sure data was read and is not the same as our clean redux state
     expect(data.components).not.toEqual(initialComponentsState)
-    expect(data).toMatchSnapshot()
+
+    // yuck - loki and redux will have different shape of redux state (nodes and nodesByType)
+    expect(_.omit(data, [`nodes`, `nodesByType`])).toMatchSnapshot()
   })
 
   it(`does not write to the cache when DANGEROUSLY_DISABLE_OOM is set`, async () => {

From bb739bd3094f46c50359ead9cd31f749b7bcccd3 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Sun, 7 Apr 2019 02:32:17 +0200
Subject: [PATCH 16/20] handle case when nodes state is null (loki) and
 v8.serialize is not available

---
 packages/gatsby/src/redux/__tests__/index.js | 1 -
 packages/gatsby/src/redux/persist.js         | 4 ++--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/packages/gatsby/src/redux/__tests__/index.js b/packages/gatsby/src/redux/__tests__/index.js
index 407b4fc7f3162..7c14ff137b613 100644
--- a/packages/gatsby/src/redux/__tests__/index.js
+++ b/packages/gatsby/src/redux/__tests__/index.js
@@ -1,4 +1,3 @@
-// const path = require(`path`)
 const _ = require(`lodash`)
 
 const writeToCache = jest.spyOn(require(`../persist`), `writeToCache`)
diff --git a/packages/gatsby/src/redux/persist.js b/packages/gatsby/src/redux/persist.js
index fcbe48836f42c..2436056955c05 100644
--- a/packages/gatsby/src/redux/persist.js
+++ b/packages/gatsby/src/redux/persist.js
@@ -21,7 +21,7 @@ const mapToObject = map => {
 const jsonStringify = contents => {
   contents.staticQueryComponents = mapToObject(contents.staticQueryComponents)
   contents.components = mapToObject(contents.components)
-  contents.nodes = mapToObject(contents.nodes)
+  contents.nodes = contents.nodes ? mapToObject(contents.nodes) : {}
   return stringify(contents, null, 2)
 }
 
@@ -29,7 +29,7 @@ const jsonParse = buffer => {
   const parsed = JSON.parse(buffer.toString(`utf8`))
   parsed.staticQueryComponents = objectToMap(parsed.staticQueryComponents)
   parsed.components = objectToMap(parsed.components)
-  parsed.nodes = objectToMap(parsed.nodes)
+  parsed.nodes = objectToMap(parsed.nodes || {})
   return parsed
 }
 

From 1905f2ee5207bf8662fe908cdf8639d89ff9bcbf Mon Sep 17 00:00:00 2001
From: Ward Peeters <ward@coding-tech.com>
Date: Thu, 11 Apr 2019 13:33:17 +0200
Subject: [PATCH 17/20] refactor into omitUndefined

---
 packages/gatsby/src/db/node-tracking.js | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/packages/gatsby/src/db/node-tracking.js b/packages/gatsby/src/db/node-tracking.js
index d93db5d603669..c981515fe0f03 100644
--- a/packages/gatsby/src/db/node-tracking.js
+++ b/packages/gatsby/src/db/node-tracking.js
@@ -9,6 +9,19 @@ const rootNodeMap = new WeakMap()
 
 const getRootNodeId = node => rootNodeMap.get(node)
 
+/**
+ * @param {Object} data
+ * @returns {Object} data without undefined values
+ */
+const omitUndefined = data => {
+  const isPlainObject = _.isPlainObject(data)
+  if (isPlainObject) {
+    return _.pickBy(data, p => p !== undefined)
+  }
+
+  return data.filter(p => p !== undefined)
+}
+
 /**
  * Add link between passed data and Node. This function shouldn't be used
  * directly. Use higher level `trackInlineObjectsInRootNode`
@@ -41,11 +54,7 @@ const addRootNodeToInlineObject = (data, nodeId, sanitize, isNode = false) => {
     })
 
     if (anyFieldChanged) {
-      if (isPlainObject) {
-        data = _.pickBy(returnData, p => p !== undefined)
-      } else {
-        data = returnData.filter(p => p !== undefined)
-      }
+      data = omitUndefined(returnData)
     }
 
     // don't need to track node itself

From 843497eb3d19dca879935c6cdbe48c6eb2b38ad3 Mon Sep 17 00:00:00 2001
From: Ward Peeters <ward@coding-tech.com>
Date: Thu, 11 Apr 2019 13:35:55 +0200
Subject: [PATCH 18/20] refactor into isTypeSupported

---
 packages/gatsby/src/db/node-tracking.js | 28 +++++++++++++++----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/packages/gatsby/src/db/node-tracking.js b/packages/gatsby/src/db/node-tracking.js
index c981515fe0f03..62a913c5d5d70 100644
--- a/packages/gatsby/src/db/node-tracking.js
+++ b/packages/gatsby/src/db/node-tracking.js
@@ -22,6 +22,21 @@ const omitUndefined = data => {
   return data.filter(p => p !== undefined)
 }
 
+/**
+ * @param {*} data
+ * @return {boolean}
+ */
+const isTypeSupported = data => {
+  const type = typeof data
+  const isSupported =
+    type === `number` ||
+    type === `string` ||
+    type === `boolean` ||
+    data instanceof Date
+
+  return isSupported
+}
+
 /**
  * Add link between passed data and Node. This function shouldn't be used
  * directly. Use higher level `trackInlineObjectsInRootNode`
@@ -66,17 +81,8 @@ const addRootNodeToInlineObject = (data, nodeId, sanitize, isNode = false) => {
     return data
   }
 
-  if (sanitize && data !== null) {
-    const type = typeof data
-    const isSupported =
-      type === `number` ||
-      type === `string` ||
-      type === `boolean` ||
-      data instanceof Date
-
-    if (!isSupported) {
-      return undefined
-    }
+  if (sanitize && !isTypeSupported(data)) {
+    return undefined
   }
   // either supported or not sanitizing
   return data

From 95dc28fa7fa065b17535f78cd056abff04fec949 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Thu, 11 Apr 2019 13:43:28 +0200
Subject: [PATCH 19/20] don't strip `null` from nodes

---
 packages/gatsby/src/db/node-tracking.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/gatsby/src/db/node-tracking.js b/packages/gatsby/src/db/node-tracking.js
index 62a913c5d5d70..79b583f608bce 100644
--- a/packages/gatsby/src/db/node-tracking.js
+++ b/packages/gatsby/src/db/node-tracking.js
@@ -27,6 +27,10 @@ const omitUndefined = data => {
  * @return {boolean}
  */
 const isTypeSupported = data => {
+  if (data === null) {
+    return true
+  }
+
   const type = typeof data
   const isSupported =
     type === `number` ||

From 0641283662bbb60ba9c77041f3d9621bc4629118 Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Thu, 11 Apr 2019 17:21:48 +0200
Subject: [PATCH 20/20] readCache can be pure, thanks @wardpeet

---
 packages/gatsby/src/redux/index.js | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/packages/gatsby/src/redux/index.js b/packages/gatsby/src/redux/index.js
index f5e90a24115e8..9f598a0171ef3 100644
--- a/packages/gatsby/src/redux/index.js
+++ b/packages/gatsby/src/redux/index.js
@@ -11,33 +11,32 @@ const reducers = require(`./reducers`)
 const { writeToCache, readFromCache } = require(`./persist`)
 
 // Read old node data from cache.
-let initialState = {}
 const readState = () => {
   try {
-    initialState = readFromCache()
-    if (initialState.nodes) {
+    const state = readFromCache()
+    if (state.nodes) {
       // re-create nodesByType
-      initialState.nodesByType = new Map()
-      initialState.nodes.forEach(node => {
+      state.nodesByType = new Map()
+      state.nodes.forEach(node => {
         const { type } = node.internal
-        if (!initialState.nodesByType.has(type)) {
-          initialState.nodesByType.set(type, new Map())
+        if (!state.nodesByType.has(type)) {
+          state.nodesByType.set(type, new Map())
         }
-        initialState.nodesByType.get(type).set(node.id, node)
+        state.nodesByType.get(type).set(node.id, node)
       })
     }
+    return state
   } catch (e) {
     // ignore errors.
-    initialState = {}
   }
-  return initialState
+  return {}
 }
-readState()
+
 exports.readState = readState
 
 const store = Redux.createStore(
   Redux.combineReducers({ ...reducers }),
-  initialState,
+  readState(),
   Redux.applyMiddleware(function multi({ dispatch }) {
     return next => action =>
       Array.isArray(action)