From c604a076f4e8ead6de16f5119892c40def9d3e24 Mon Sep 17 00:00:00 2001
From: Michael Drury <me@michaeldrury.co.uk>
Date: Wed, 13 Jul 2022 21:50:19 +0100
Subject: [PATCH] Adding a mechanism to deprecate a view and replace it with a
 new one.

---
 packages/backend-core/src/db/constants.ts |  9 +++++-
 packages/backend-core/src/db/views.js     | 35 +++++++++++++++++++----
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/packages/backend-core/src/db/constants.ts b/packages/backend-core/src/db/constants.ts
index be0e824e61..716762dd45 100644
--- a/packages/backend-core/src/db/constants.ts
+++ b/packages/backend-core/src/db/constants.ts
@@ -11,7 +11,7 @@ export enum AutomationViewModes {
 }
 
 export enum ViewNames {
-  USER_BY_EMAIL = "by_email",
+  USER_BY_EMAIL = "by_email2",
   BY_API_KEY = "by_api_key",
   USER_BY_BUILDERS = "by_builders",
   LINK = "by_link",
@@ -19,6 +19,13 @@ export enum ViewNames {
   AUTOMATION_LOGS = "automation_logs",
 }
 
+export const DeprecatedViews = {
+  [ViewNames.USER_BY_EMAIL]: [
+    // removed due to inaccuracy in view doc filter logic
+    "by_email",
+  ],
+}
+
 export enum DocumentTypes {
   USER = "us",
   WORKSPACE = "workspace",
diff --git a/packages/backend-core/src/db/views.js b/packages/backend-core/src/db/views.js
index e0281c6584..1e8dd7ee77 100644
--- a/packages/backend-core/src/db/views.js
+++ b/packages/backend-core/src/db/views.js
@@ -1,20 +1,42 @@
-const { DocumentTypes, ViewNames } = require("./utils")
+const {
+  DocumentTypes,
+  ViewNames,
+  DeprecatedViews,
+  SEPARATOR,
+} = require("./utils")
 const { getGlobalDB } = require("../tenancy")
 
+const DESIGN_DB = "_design/database"
+
 function DesignDoc() {
   return {
-    _id: "_design/database",
+    _id: DESIGN_DB,
     // view collation information, read before writing any complex views:
     // https://docs.couchdb.org/en/master/ddocs/views/collation.html#collation-specification
     views: {},
   }
 }
 
-exports.createUserEmailView = async () => {
+async function removeDeprecated(db, viewName) {
+  if (!DeprecatedViews[viewName]) {
+    return
+  }
+  try {
+    const designDoc = await db.get(DESIGN_DB)
+    for (let deprecatedNames of DeprecatedViews[viewName]) {
+      delete designDoc.views[deprecatedNames]
+    }
+    await db.put(designDoc)
+  } catch (err) {
+    // doesn't exist, ignore
+  }
+}
+
+exports.createNewUserEmailView = async () => {
   const db = getGlobalDB()
   let designDoc
   try {
-    designDoc = await db.get("_design/database")
+    designDoc = await db.get(DESIGN_DB)
   } catch (err) {
     // no design doc, make one
     designDoc = DesignDoc()
@@ -22,7 +44,7 @@ exports.createUserEmailView = async () => {
   const view = {
     // if using variables in a map function need to inject them before use
     map: `function(doc) {
-      if (doc._id.startsWith("${DocumentTypes.USER}")) {
+      if (doc._id.startsWith("${DocumentTypes.USER}${SEPARATOR}")) {
         emit(doc.email.toLowerCase(), doc._id)
       }
     }`,
@@ -81,7 +103,7 @@ exports.createUserBuildersView = async () => {
 
 exports.queryGlobalView = async (viewName, params, db = null) => {
   const CreateFuncByName = {
-    [ViewNames.USER_BY_EMAIL]: exports.createUserEmailView,
+    [ViewNames.USER_BY_EMAIL]: exports.createNewUserEmailView,
     [ViewNames.BY_API_KEY]: exports.createApiKeyView,
     [ViewNames.USER_BY_BUILDERS]: exports.createUserBuildersView,
   }
@@ -98,6 +120,7 @@ exports.queryGlobalView = async (viewName, params, db = null) => {
   } catch (err) {
     if (err != null && err.name === "not_found") {
       const createFunc = CreateFuncByName[viewName]
+      await removeDeprecated(db, viewName)
       await createFunc()
       return exports.queryGlobalView(viewName, params)
     } else {