API: Remove 'immer' dependency

'immer' didn't really work for us and led to all kinds of hard-to-debug
problems. Instead of relying on 'immer' to handle changes during event
sourcing, we now carefully deep-copy relevant data in the
`*_eventsourcing.ts` files and have the event-specific modules `mutate`
the aggregate in-place. This makes the latter very simple; at the same
time we ensure that the aggregates stored in the cache aren't changed
outside the cache.

Affected aggregates:

- project
- subproject
- workflowitem

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Fixed
+
+- [API] Increased the stability of the event sourcing code by replacing the "immer" dependency with a custom implementation.
+
 ## [1.0.0-beta.7] - 2019-04-03
 
 ### Added

api/package.json

@@ -74,7 +74,6 @@
     "fastify-jwt": "^0.3.0",
     "fastify-metrics": "^2.0.2",
     "fastify-swagger": "^0.15.0",
-    "immer": "^2.1.3",
     "joi": "^14.3.1",
     "jsonwebtoken": "^8.5.0",
     "lodash.clonedeep": "^4.5.0",

api/src/http_errors/bad_request.ts

@@ -0,0 +1,16 @@
+import Joi = require("joi");
+import { VError } from "verror";
+
+import { Ctx } from "../lib/ctx";
+
+interface Info {
+  ctx: Ctx;
+  requestPath: string;
+  validationResult: Joi.ValidationError;
+}
+
+export class BadRequest extends VError {
+  constructor(info: Info) {
+    super({ name: "BadRequest", info }, `invalid request to ${info.requestPath}`);
+  }
+}

api/src/service/cache2.spec.ts

@@ -182,15 +182,15 @@ describe("The cache updates", () => {
 
       // Apply events to existing cache
       const testAssignee = "shiba";
-      const wfAssginedEvent = WorkflowitemAssigned.createEvent(
+      const wfAssignedEvent = WorkflowitemAssigned.createEvent(
         "http",
         "test",
         projectId,
         subprojectId,
         workflowitemId,
         testAssignee,
       );
-      if (Result.isErr(wfAssginedEvent)) {
+      if (Result.isErr(wfAssignedEvent)) {
         return assert.fail(undefined, undefined, "Workflowitem assigned event failed");
       }
       const wfCloseEvent = WorkflowitemClosed.createEvent(
@@ -203,7 +203,7 @@ describe("The cache updates", () => {
       if (Result.isErr(wfCloseEvent)) {
         return assert.fail(undefined, undefined, "Workflowitem closed event failed");
       }
-      updateAggregates(defaultCtx, cache, [wfAssginedEvent, wfCloseEvent]);
+      updateAggregates(defaultCtx, cache, [wfAssignedEvent, wfCloseEvent]);
 
       // Test if events have been reflected on the aggregate
       const wfUnderTest = cache.cachedWorkflowItems.get(workflowitemId);

api/src/service/cache2.ts

@@ -1,5 +1,4 @@
 import { Ctx } from "../lib/ctx";
-import deepcopy from "../lib/deepcopy";
 import { isEmpty } from "../lib/emptyChecks";
 import logger from "../lib/logger";
 import * as Result from "../result";
@@ -31,7 +30,6 @@ import * as SubprojectAssigned from "./domain/workflow/subproject_assigned";
 import * as SubprojectClosed from "./domain/workflow/subproject_closed";
 import * as SubprojectCreated from "./domain/workflow/subproject_created";
 import { sourceSubprojects } from "./domain/workflow/subproject_eventsourcing";
-import * as WorkflowitemsReordered from "./domain/workflow/workflowitems_reordered";
 import * as SubprojectPermissionsGranted from "./domain/workflow/subproject_permission_granted";
 import * as SubprojectPermissionsRevoked from "./domain/workflow/subproject_permission_revoked";
 import * as SubprojectProjectedBudgetDeleted from "./domain/workflow/subproject_projected_budget_deleted";
@@ -45,6 +43,7 @@ import { sourceWorkflowitems } from "./domain/workflow/workflowitem_eventsourcin
 import * as WorkflowitemPermissionsGranted from "./domain/workflow/workflowitem_permission_granted";
 import * as WorkflowitemPermissionsRevoked from "./domain/workflow/workflowitem_permission_revoked";
 import * as WorkflowitemUpdated from "./domain/workflow/workflowitem_updated";
+import * as WorkflowitemsReordered from "./domain/workflow/workflowitems_reordered";
 import { Item } from "./liststreamitems";
 
 const STREAM_BLACKLIST = [
@@ -117,17 +116,17 @@ export type TransactionFn<T> = (cache: CacheInstance) => Promise<T>;
 export function getCacheInstance(ctx: Ctx, cache: Cache2): CacheInstance {
   return {
     getGlobalEvents: (): BusinessEvent[] => {
-      return deepcopy(cache.eventsByStream.get("global")) || [];
+      return cache.eventsByStream.get("global") || [];
     },
 
     getUserEvents: (_userId?: string): BusinessEvent[] => {
       // userId currently not leveraged
-      return deepcopy(cache.eventsByStream.get("users")) || [];
+      return cache.eventsByStream.get("users") || [];
     },
 
     getGroupEvents: (_groupId?: string): BusinessEvent[] => {
       // groupId currently not leveraged
-      return deepcopy(cache.eventsByStream.get("groups")) || [];
+      return cache.eventsByStream.get("groups") || [];
     },
 
     getNotificationEvents: (userId: string): BusinessEvent[] => {
@@ -147,11 +146,11 @@ export function getCacheInstance(ctx: Ctx, cache: Cache2): CacheInstance {
         }
       };
 
-      return (deepcopy(cache.eventsByStream.get("notifications")) || []).filter(userFilter);
+      return (cache.eventsByStream.get("notifications") || []).filter(userFilter);
     },
 
     getProjects: async (): Promise<Project.Project[]> => {
-      return deepcopy([...cache.cachedProjects.values()]);
+      return [...cache.cachedProjects.values()];
     },
 
     getProject: async (projectId: string): Promise<Result.Type<Project.Project>> => {
@@ -160,7 +159,7 @@ export function getCacheInstance(ctx: Ctx, cache: Cache2): CacheInstance {
       if (project === undefined) {
         return new NotFound(ctx, "project", projectId);
       }
-      return deepcopy(project);
+      return project;
     },
 
     getSubprojects: async (projectId: string): Promise<Result.Type<Subproject.Subproject[]>> => {
@@ -180,7 +179,7 @@ export function getCacheInstance(ctx: Ctx, cache: Cache2): CacheInstance {
         }
         subprojects.push(sp);
       }
-      return deepcopy(subprojects);
+      return subprojects;
     },
 
     getSubproject: (
@@ -191,7 +190,7 @@ export function getCacheInstance(ctx: Ctx, cache: Cache2): CacheInstance {
       if (subproject === undefined) {
         return new NotFound(ctx, "subproject", subprojectId);
       }
-      return deepcopy(subproject);
+      return subproject;
     },
 
     getWorkflowitems: async (
@@ -213,7 +212,7 @@ export function getCacheInstance(ctx: Ctx, cache: Cache2): CacheInstance {
         }
         workflowitems.push(wf);
       }
-      return deepcopy(workflowitems);
+      return workflowitems;
     },
 
     getWorkflowitem: async (
@@ -225,7 +224,7 @@ export function getCacheInstance(ctx: Ctx, cache: Cache2): CacheInstance {
       if (workflowitem === undefined) {
         return new NotFound(ctx, "workflowitem", workflowitemId);
       }
-      return deepcopy(workflowitem);
+      return workflowitem;
     },
   };
 }

api/src/service/domain/workflow/project_assign.ts

@@ -1,5 +1,5 @@
-import { produce } from "immer";
 import { VError } from "verror";
+
 import { Ctx } from "../../../lib/ctx";
 import * as Result from "../../../result";
 import { BusinessEvent } from "../business_event";
@@ -12,6 +12,7 @@ import * as UserRecord from "../organization/user_record";
 import * as NotificationCreated from "./notification_created";
 import * as Project from "./project";
 import * as ProjectAssigned from "./project_assigned";
+import * as ProjectEventSourcing from "./project_eventsourcing";
 
 interface Repository {
   getProject(): Promise<Result.Type<Project.Project>>;
@@ -48,7 +49,7 @@ export async function assignProject(
   }
 
   // Check that the new event is indeed valid:
-  const result = produce(project, draft => ProjectAssigned.apply(ctx, projectAssigned, draft));
+  const result = ProjectEventSourcing.newProjectFromEvent(ctx, project, projectAssigned);
   if (Result.isErr(result)) {
     return new InvalidCommand(ctx, projectAssigned, [result]);
   }