perf: add an ability to merge specific versions (#46)

* refactor: remove updatedAt field from diff doc

* feat: add startVersion & endVersion args to mergeDiffs method

* test: cover mergeDiffs methods with additional cases

Co-authored-by: Valeriy Borodayev <[email protected]>

Author: borodayev

__fixtures__/Post.ts

@@ -1,3 +1,4 @@
+/* eslint-disable no-await-in-loop */
 // @flow
 /* eslint-disable no-param-reassign, func-names */
 
@@ -7,6 +8,16 @@ import DB from './db';
 
 DB.init();
 
+export interface IPostDoc extends Document {
+  title: string;
+  subjects: Array<{ name: string }>;
+}
+
+interface IPostModel extends Model<IPostDoc> {
+  diffModel(): IDiffModel;
+  createDifferentSubjects(findObj: string, count: number): Promise<void>;
+}
+
 export const PostSchema: Schema<IPostDoc> = new mongoose.Schema(
   {
     title: {
@@ -34,14 +45,19 @@ export const PostSchema: Schema<IPostDoc> = new mongoose.Schema(
   }
 );
 
-export interface IPostDoc extends Document {
-  title: string;
-  subjects: Array<{ name: string }>;
-}
-
-interface IPostModel extends Model<IPostDoc> {
-  diffModel(): IDiffModel;
-}
+// for test purposes
+PostSchema.statics.createDifferentSubjects = async function (
+  title: string,
+  count: number
+): Promise<void> {
+  for (let i = 1; i <= count; i += 1) {
+    const post: IPostDoc = await this.findOne({ title }).exec();
+    if (post) {
+      post.subjects.push({ name: `name_${i}` });
+      await post.save();
+    }
+  }
+};
 
 PostSchema.plugin(DiffPlugin);
 

src/DiffModel.ts

@@ -1,13 +1,20 @@
 /* eslint-disable func-names */
 import { Schema, Connection } from 'mongoose';
-import { IDiffModel, ObjectId, RawChangeT, ChangeDoc, IDiffDoc } from './types';
+import {
+  IDiffModel,
+  ObjectId,
+  RawChangeT,
+  ChangeDoc,
+  IDiffDoc,
+  MergedDiffsOptsT,
+} from './types';
 import MHD, { revertChanges } from './diff';
 
 export default function (
   mongooseConnection: Connection,
   collectionName: string
 ): IDiffModel {
-  if (!mongooseConnection) throw new Error(`'mongooseConection' is required`);
+  if (!mongooseConnection) throw new Error(`'mongooseConnection' is required`);
   if (!collectionName) throw new Error(`'collectionName' is required`);
 
   const ItemSchema = new Schema(
@@ -49,7 +56,11 @@ export default function (
       c: [ChangeSchema],
       v: Number,
     },
-    { versionKey: false, timestamps: true, collection: collectionName }
+    {
+      versionKey: false,
+      timestamps: { createdAt: true, updatedAt: false },
+      collection: collectionName,
+    }
   );
   DiffSchema.index({ docId: 1, path: 1 });
 
@@ -103,12 +114,40 @@ export default function (
     return revertChanges(doc, changes);
   };
 
-  DiffSchema.statics.mergeDiffs = async function (doc: {
-    toObject: Function;
-  }): Promise<Array<RawChangeT>> {
-    const currentDoc = { ...doc.toObject() };
-    const initialDoc = await this.revertToVersion(currentDoc, 1);
-    if (!initialDoc) return [];
+  DiffSchema.statics.mergeDiffs = async function (
+    doc: {
+      toObject: Function;
+    },
+    opts?: MergedDiffsOptsT
+  ): Promise<Array<RawChangeT>> {
+    const { startVersion, endVersion } = opts || {};
+
+    if (typeof startVersion === 'number' && startVersion < 1)
+      throw new Error(
+        `"startVersion" argument should be >= 1, but got: ${startVersion}`
+      );
+
+    if (typeof endVersion === 'number' && endVersion < 1)
+      throw new Error(
+        `"endVersion" argument should be >= 1, but got: ${endVersion}`
+      );
+
+    let initialDoc = null;
+    let currentDoc = { ...doc.toObject() };
+
+    if (startVersion && endVersion) {
+      initialDoc = await this.revertToVersion(currentDoc, startVersion);
+      currentDoc = await this.revertToVersion(currentDoc, endVersion);
+    } else if (startVersion) {
+      initialDoc = await this.revertToVersion(currentDoc, startVersion);
+    } else if (endVersion) {
+      initialDoc = await this.revertToVersion(currentDoc, 1);
+      currentDoc = await this.revertToVersion(currentDoc, endVersion);
+    } else {
+      initialDoc = await this.revertToVersion(currentDoc, 1);
+    }
+
+    if (!initialDoc || !currentDoc) return [];
     return MHD.findDiff(initialDoc, currentDoc);
   };