fix: check for dirty pages when nodes are deleted (so queries are ru-…

…run and data is removed from pages) (#11831)

* fix: check for dirty pages when nodes are deleted (so queries are ru-run and data is removed from pages)

* typo fix

* Use fake API call as suggested by @pieh

* better name

* Fix comparision as page.updatedAt is a unix timestamp

* Remove page when deleted from internal query running cache so it can be run again if page recreated

* WIP

* MORE WIP

* Revert "MORE WIP"

This reverts commit 890fb36.

* Revert "WIP"

This reverts commit 190625f.

* Document FAKE_API_CALL

packages/gatsby/src/bootstrap/page-hot-reloader.js

@@ -16,6 +16,11 @@ emitter.on(`CREATE_NODE`, action => {
 emitter.on(`DELETE_NODE`, action => {
   if (action.payload.internal.type !== `SitePage`) {
     pagesDirty = true
+    // Make a fake API call to trigger `API_RUNNING_QUEUE_EMPTY` being called.
+    // We don't want to call runCreatePages here as there might be work in
+    // progress. So this is a safe way to make sure runCreatePages gets called
+    // at a safe time.
+    apiRunnerNode(`FAKE_API_CALL`)
   }
 })
 
@@ -45,7 +50,7 @@ const runCreatePages = async () => {
     })
     .map(p => p.id)
 
-  const timestamp = new Date().toJSON()
+  const timestamp = Date.now()
 
   await apiRunnerNode(`createPages`, {
     graphql,

packages/gatsby/src/internal-plugins/query-runner/page-query-runner.js

@@ -93,6 +93,15 @@ exports.runQueuedActions = runQueuedActions
 emitter.on(`API_RUNNING_QUEUE_EMPTY`, runQueuedActions)
 
 let seenIdsWithoutDataDependencies = []
+
+// Remove pages from seenIdsWithoutDataDependencies when they're deleted
+// so their query will be run again if they're created again.
+emitter.on(`DELETE_PAGE`, action => {
+  seenIdsWithoutDataDependencies = seenIdsWithoutDataDependencies.filter(
+    p => p !== action.payload.path
+  )
+})
+
 const findIdsWithoutDataDependencies = () => {
   const state = store.getState()
   const allTrackedIds = _.uniq(

packages/gatsby/src/utils/api-runner-node.js

@@ -201,7 +201,11 @@ module.exports = async (api, args = {}, pluginSource) =>
     })
 
     // Check that the API is documented.
-    if (!apiList[api]) {
+    // "FAKE_API_CALL" is used when code needs to trigger something
+    // to happen once the the API queue is empty. Ideally of course
+    // we'd have an API (returning a promise) for that. But this
+    // works nicely in the meantime.
+    if (!apiList[api] && api !== `FAKE_API_CALL`) {
       reporter.panic(`api: "${api}" is not a valid Gatsby api`)
     }