feat(core): add Collection.slice() method (#4608)

Adds support for `Collection.slice()` --------- Co-authored-by: Martin Adámek <banan23@gmail.com>
mikro-orm · Aug 11, 2023 · 7c99c37 · 7c99c37
1 parent 79af75c
commit 7c99c37
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Showing 22 changed files with 104 additions and 17 deletions.
diff --git a/.eslintrc.js b/.eslintrc.js
@@ -148,7 +148,8 @@ module.exports = {
     'space-before-blocks': ['error', 'always'],
     'brace-style': ['error', '1tbs', { allowSingleLine: true }],
     'keyword-spacing': ['error', { before: true, after: true }],
-    'space-in-parens': ['error', 'never']
+    'space-in-parens': ['error', 'never'],
+    'comma-spacing': 'error',
   },
   'settings': {}
 };
diff --git a/docs/docs/collections.md b/docs/docs/collections.md
@@ -40,6 +40,9 @@ author.books.remove(book);
 console.log(author.books.contains(book)); // false
 author.books.add(book);
 console.log(author.books.count()); // 1
+console.log(author.books.slice(0, 1)); // Book[]
+console.log(author.books.slice()); // Book[]
+console.log(author.books.slice().length); // 1
 author.books.removeAll();
 console.log(author.books.isEmpty()); // true
 console.log(author.books.contains(book)); // false

diff --git a/packages/core/src/entity/ArrayCollection.ts b/packages/core/src/entity/ArrayCollection.ts
@@ -177,6 +177,31 @@ export class ArrayCollection<T extends object, O extends object> {
     return this.items.has(entity);
   }
 
+
+  /**
+   * Extracts a slice of elements starting at position start to end (exclusive) of the collection.
+   * If end is null it returns all elements from start to the end of the collection.
+   */
+  slice(start = 0, end?: number): T[] {
+    let index = 0;
+    end ??= this.items.size;
+    const items: T[] = [];
+
+    for (const item of this.items) {
+      if (index === end) {
+        break;
+      }
+
+      if (index >= start && index < end) {
+        items.push(item);
+      }
+
+      index++;
+    }
+
+    return items;
+  }
+
   count(): number {
     return this.items.size;
   }

diff --git a/packages/core/src/entity/Collection.ts b/packages/core/src/entity/Collection.ts
@@ -204,6 +204,14 @@ export class Collection<T extends object, O extends object = object> extends Arr
     return super.isEmpty();
   }
 
+  /**
+   * @inheritDoc
+   */
+  slice(start?: number, end?: number): T[]  {
+    this.checkInitialized();
+    return super.slice(start, end);
+  }
+
   shouldPopulate(): boolean {
     return this._populated && !this._lazyInitialized;
   }

diff --git a/packages/seeder/src/SeedManager.ts b/packages/seeder/src/SeedManager.ts
@@ -1,5 +1,5 @@
 import globby from 'globby';
-import type { Constructor, EntityManager, ISeedManager , MikroORM } from '@mikro-orm/core';
+import type { Constructor, EntityManager, ISeedManager, MikroORM } from '@mikro-orm/core';
 import { Utils } from '@mikro-orm/core';
 import type { Seeder } from './Seeder';
 import { ensureDir, writeFile } from 'fs-extra';

diff --git a/tests/EntityManager.mongo.test.ts b/tests/EntityManager.mongo.test.ts
@@ -846,6 +846,12 @@ describe('EntityManagerMongo', () => {
     book = (await orm.em.findOne(Book, book._id))!;
     expect(book.tags.count()).toBe(2);
 
+    // slice
+    expect(book.tags.slice()).toEqual(items);
+    expect(book.tags.slice(0, 2)).toEqual(items);
+    expect(book.tags.slice(1)).toEqual([items[1], items[2]]);
+    expect(book.tags.slice(0, 1)).toEqual([items[0]]);
+
     // contains
     expect(book.tags.contains(tagRepository.getReference(tag1.id))).toBe(true);
     expect(book.tags.contains(tagRepository.getReference(tag2.id))).toBe(false);

diff --git a/tests/EntityManager.mysql.test.ts b/tests/EntityManager.mysql.test.ts
@@ -1188,6 +1188,12 @@ describe('EntityManagerMySql', () => {
     book = (await orm.em.findOne(Book2, book.uuid, { populate: ['tags'] as const }))!;
     expect(book.tags.count()).toBe(3);
 
+    // slice
+    expect(book.tags.slice().length).toBe(3);
+    expect(book.tags.slice(0, 3).length).toBe(3);
+    expect(book.tags.slice(0, 1)).toEqual([book.tags[0]]);
+    expect(book.tags.slice(1, 2)).toEqual([book.tags[1]]);
+
     // contains
     expect(book.tags.contains(tagRepository.getReference(tag1.id))).toBe(true);
     expect(book.tags.contains(tagRepository.getReference(tag2.id))).toBe(false);

diff --git a/tests/EntityManager.postgre.test.ts b/tests/EntityManager.postgre.test.ts
@@ -1133,6 +1133,8 @@ describe('EntityManagerPostgre', () => {
     orm.em.clear();
     book = (await orm.em.findOne(Book2, book.uuid, { populate: ['tags'] as const }))!;
     expect(book.tags.count()).toBe(3);
+    expect(book.tags.slice().length).toBe(3);
+    expect(book.tags.slice(0, 1)).toEqual([book.tags[0]]);
 
     // contains
     expect(book.tags.contains(tagRepository.getReference(tag1.id))).toBe(true);
@@ -1956,7 +1958,7 @@ describe('EntityManagerPostgre', () => {
     }
 
     console.time('perf: one to many via em.create()');
-    const author = orm.em.create(Author2,{
+    const author = orm.em.create(Author2, {
       name: 'Jon Snow',
       email: 'snow@wall.st',
       books,

diff --git a/tests/EntityManager.sqlite.test.ts b/tests/EntityManager.sqlite.test.ts
@@ -671,6 +671,11 @@ describe('EntityManagerSqlite', () => {
     book = (await orm.em.findOne(Book3, book.id, { populate: ['tags'] as const }))!;
     expect(book.tags.count()).toBe(2);
 
+    // slice
+    expect(book.tags.slice().length).toBe(2);
+    expect(book.tags.slice(0, 2).length).toBe(2);
+    expect(book.tags.slice(0, 1)).toEqual([book.tags[0]]);
+
     // contains
     expect(book.tags.contains(tagRepository.getReference(tag1.id))).toBe(true);
     expect(book.tags.contains(tagRepository.getReference(tag2.id))).toBe(false);

diff --git a/tests/EntityManager.sqlite2.test.ts b/tests/EntityManager.sqlite2.test.ts
@@ -674,6 +674,11 @@ describe.each(['sqlite', 'better-sqlite'] as const)('EntityManager (%s)', driver
     book = (await orm.em.findOne(Book4, book.id, { populate: ['tags'] as const }))!;
     expect(book.tags.count()).toBe(2);
 
+    // slice
+    expect(book.tags.slice().length).toBe(2);
+    expect(book.tags.slice(0, 2).length).toBe(2);
+    expect(book.tags.slice(0, 1)).toEqual([book.tags[0]]);
+
     // contains
     expect(book.tags.contains(tagRepository.getReference(tag1.id))).toBe(true);
     expect(book.tags.contains(tagRepository.getReference(tag2.id))).toBe(false);

diff --git a/tests/QueryBuilder.test.ts b/tests/QueryBuilder.test.ts
@@ -2942,7 +2942,7 @@ describe('QueryBuilder', () => {
     spy.mockRestore();
   });
 
-  test('limit of 0 limits results to 0',()=>{
+  test('limit of 0 limits results to 0', () => {
     const expected = 'select `e0`.`id` from `book2` as `e0` limit 0';
     const sql = orm.em.createQueryBuilder(Book2).select('id').limit(0).getFormattedQuery();
     expect(sql).toBe(expected);

diff --git a/tests/entities-schema/Book4.ts b/tests/entities-schema/Book4.ts
@@ -1,4 +1,4 @@
-import type { Collection, Reference , OptionalProps } from '@mikro-orm/core';
+import type { Collection, Reference, OptionalProps } from '@mikro-orm/core';
 import { EntitySchema, t } from '@mikro-orm/core';
 import type { IBaseEntity5 } from './BaseEntity5';
 import type { IAuthor4 } from './Author4';

diff --git a/tests/entities-schema/BookTag4.ts b/tests/entities-schema/BookTag4.ts
@@ -1,4 +1,4 @@
-import type { Collection , OptionalProps } from '@mikro-orm/core';
+import type { Collection, OptionalProps } from '@mikro-orm/core';
 import { EntitySchema } from '@mikro-orm/core';
 import type { IBaseEntity5 } from './BaseEntity5';
 import type { IBook4 } from './Book4';

diff --git a/tests/entities-schema/Publisher4.ts b/tests/entities-schema/Publisher4.ts
@@ -1,4 +1,4 @@
-import type { Collection , OptionalProps } from '@mikro-orm/core';
+import type { Collection, OptionalProps } from '@mikro-orm/core';
 import { EntitySchema } from '@mikro-orm/core';
 import type { IBaseEntity5 } from './BaseEntity5';
 import type { IBook4 } from './Book4';

diff --git a/tests/features/composite-keys/custom-pivot-entity-auto-discovery.sqlite.test.ts b/tests/features/composite-keys/custom-pivot-entity-auto-discovery.sqlite.test.ts
@@ -201,6 +201,11 @@ describe('custom pivot entity for m:n with additional properties (auto-discovere
     order = (await orm.em.findOne(Order, order.id, { populate: ['products'] as const }))!;
     expect(order.products.count()).toBe(3);
 
+    // slice
+    expect(order.products.slice().length).toBe(3);
+    expect(order.products.slice(0, 3).length).toBe(3);
+    expect(order.products.slice(0, 1)).toEqual([order.products[0]]);
+
     // contains
     expect(order.products.contains(productRepository.getReference(product1.id))).toBe(true);
     expect(order.products.contains(productRepository.getReference(product2.id))).toBe(true);

diff --git a/tests/features/composite-keys/custom-pivot-entity-fixed-order.sqlite.test.ts b/tests/features/composite-keys/custom-pivot-entity-fixed-order.sqlite.test.ts
@@ -162,6 +162,11 @@ describe('custom pivot entity for m:n with additional properties (unidirectional
     order = (await orm.em.findOne(Order, order.id, { populate: ['products'] as const }))!;
     expect(order.products.count()).toBe(3);
 
+    // slice
+    expect(order.products.slice().length).toBe(3);
+    expect(order.products.slice(0, 3).length).toBe(3);
+    expect(order.products.slice(0, 1)).toEqual([order.products[0]]);
+
     // contains
     expect(order.products.contains(productRepository.getReference(product1.id))).toBe(true);
     expect(order.products.contains(productRepository.getReference(product2.id))).toBe(true);

diff --git a/tests/features/composite-keys/custom-pivot-entity-uni.sqlite.test.ts b/tests/features/composite-keys/custom-pivot-entity-uni.sqlite.test.ts
@@ -156,6 +156,12 @@ describe('custom pivot entity for m:n with additional properties (unidirectional
     order = (await orm.em.findOne(Order, order.id, { populate: ['products'] as const }))!;
     expect(order.products.count()).toBe(3);
 
+
+    // slice
+    expect(order.products.slice().length).toBe(3);
+    expect(order.products.slice(0, 3).length).toBe(3);
+    expect(order.products.slice(0, 1)).toEqual([order.products[0]]);
+
     // contains
     expect(order.products.contains(productRepository.getReference(product1.id))).toBe(true);
     expect(order.products.contains(productRepository.getReference(product2.id))).toBe(true);

diff --git a/tests/features/composite-keys/custom-pivot-entity-wrong-order.sqlite.test.ts b/tests/features/composite-keys/custom-pivot-entity-wrong-order.sqlite.test.ts
@@ -197,6 +197,11 @@ describe('custom pivot entity for m:n with additional properties (bidirectional,
     order = (await orm.em.findOne(Order, order.id, { populate: ['products'] as const }))!;
     expect(order.products.count()).toBe(3);
 
+    // slice
+    expect(order.products.slice().length).toBe(3);
+    expect(order.products.slice(0, 3).length).toBe(3);
+    expect(order.products.slice(0, 1)).toEqual([order.products[0]]);
+
     // contains
     expect(order.products.contains(productRepository.getReference(product1.id))).toBe(true);
     expect(order.products.contains(productRepository.getReference(product2.id))).toBe(true);

diff --git a/tests/features/composite-keys/custom-pivot-entity.sqlite.test.ts b/tests/features/composite-keys/custom-pivot-entity.sqlite.test.ts
@@ -197,6 +197,11 @@ describe('custom pivot entity for m:n with additional properties (bidirectional)
     order = (await orm.em.findOne(Order, order.id, { populate: ['products'] as const }))!;
     expect(order.products.count()).toBe(3);
 
+    // slice
+    expect(order.products.slice().length).toBe(3);
+    expect(order.products.slice(0, 3).length).toBe(3);
+    expect(order.products.slice(0, 1)).toEqual([order.products[0]]);
+
     // contains
     expect(order.products.contains(productRepository.getReference(product1.id))).toBe(true);
     expect(order.products.contains(productRepository.getReference(product2.id))).toBe(true);

diff --git a/tests/features/read-replicas.test.ts b/tests/features/read-replicas.test.ts
@@ -81,7 +81,7 @@ describe('read-replicas', () => {
       expect(mock.mock.calls[4][0]).toMatch(/via read connection 'read-.*'/);
 
       // explicitly set to read
-      await orm.em.findOne(Author2, author, { connectionType: 'read',refresh: true });
+      await orm.em.findOne(Author2, author, { connectionType: 'read', refresh: true });
       expect(mock.mock.calls[5][0]).toMatch(/via read connection 'read-.*'/);
 
       // explicitly set to write
@@ -109,16 +109,16 @@ describe('read-replicas', () => {
       expect(mock.mock.calls[4][0]).toMatch(/via read connection 'read-.*'/);
 
       // explicitly set to read
-      await orm.em.count(Author2, {},{ connectionType: 'read' });
+      await orm.em.count(Author2, {}, { connectionType: 'read' });
       expect(mock.mock.calls[5][0]).toMatch(/via read connection 'read-.*'/);
 
       // explicitly set to write
-      await orm.em.count(Author2, {},{ connectionType: 'write' });
+      await orm.em.count(Author2, {}, { connectionType: 'write' });
       expect(mock.mock.calls[6][0]).toMatch(/via write connection '127\.0\.0\.1'/);
 
       // when running in a transaction will always use a write connection
       await orm.em.transactional(async em => {
-        return em.count(Author2, {},{ connectionType: 'read' });
+        return em.count(Author2, {}, { connectionType: 'read' });
       });
       expect(mock.mock.calls[7][0]).toMatch(/begin.*via write connection '127\.0\.0\.1'/);
       expect(mock.mock.calls[8][0]).toMatch(/select.*via write connection '127\.0\.0\.1'/);
@@ -185,7 +185,7 @@ describe('read-replicas', () => {
       expect(mock.mock.calls[4][0]).toMatch(/via write connection '127\.0\.0\.1'/);
 
       // explicitly set to read
-      await orm.em.findOne(Author2, author, { connectionType: 'read',refresh: true });
+      await orm.em.findOne(Author2, author, { connectionType: 'read', refresh: true });
       expect(mock.mock.calls[5][0]).toMatch(/via read connection 'read-.*'/);
 
       // explicitly set to write
@@ -215,16 +215,16 @@ describe('read-replicas', () => {
       expect(mock.mock.calls[4][0]).toMatch(/via write connection '127\.0\.0\.1'/);
 
       // explicitly set to read
-      await orm.em.count(Author2, {},{ connectionType: 'read' });
+      await orm.em.count(Author2, {}, { connectionType: 'read' });
       expect(mock.mock.calls[5][0]).toMatch(/via read connection 'read-.*'/);
 
       // explicitly set to write
-      await orm.em.count(Author2, {},{ connectionType: 'write' });
+      await orm.em.count(Author2, {}, { connectionType: 'write' });
       expect(mock.mock.calls[6][0]).toMatch(/via write connection '127\.0\.0\.1'/);
 
       // when running in a transaction will always use a write connection
       await orm.em.transactional(async em => {
-        return em.count(Author2, {},{ connectionType: 'read' });
+        return em.count(Author2, {}, { connectionType: 'read' });
       });
       expect(mock.mock.calls[7][0]).toMatch(/begin.*via write connection '127\.0\.0\.1'/);
       expect(mock.mock.calls[8][0]).toMatch(/select.*via write connection '127\.0\.0\.1'/);

diff --git a/tests/issues/GH2379.test.ts b/tests/issues/GH2379.test.ts
@@ -110,7 +110,7 @@ describe('GH issue 2379', () => {
 
   beforeAll(async () => {
     orm = await MikroORM.init({
-      entities: [Order, Job, VendorBuyerRelationship,Member],
+      entities: [Order, Job, VendorBuyerRelationship, Member],
       dbName: ':memory:',
       driver: SqliteDriver,
     });

diff --git a/tests/issues/GH2815.test.ts b/tests/issues/GH2815.test.ts
@@ -29,7 +29,7 @@ export class Position2 {
   @PrimaryKey()
   id!: number;
 
-  @OneToOne(() => Leg2, (leg: Leg2) => leg.position, { owner: true, nullable: true , orphanRemoval: true })
+  @OneToOne(() => Leg2, (leg: Leg2) => leg.position, { owner: true, nullable: true, orphanRemoval: true })
   leg?: any;
 
 }