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wesleygrimeswesleygrimes
committedJul 30, 2019
Updated to version 0.0.2
·
v2.0.3v1.0.0
1 parent 12283cb commit cf6ce61

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‎.prettierrc

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{
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"trailingComma": "all",
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"singleQuote": true
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}

‎README.md

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# NestJS Addons - In-Memory DB Service
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# NestJS Addons: In-Memory DB Service
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## Description
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Coming soon...
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`@nestjs-addons/in-memory-db` provides a ridiculously simple, no configuration needed, way to create a simple in-memory database for use in your `nestjs` applications. You simply define an `interface` that extends the `interface InMemoryEntity`, inject the `InMemoryDBService<T>` into your controllers and/or services, and immediately profit. The records are stored in-memory, as a singleton, for each interface, for the life of the service.
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This provides a great way to quickly get up and running with prototypes and mock backends.
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## Installation
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## Quick Start
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Coming soon...
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### Import into Module(s)
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To get started, let's first update our `app.module.ts` to include the necessary pieces.
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> While we are importing to the AppModule in this example, InMemoryDBModule could be imported in Feature modules just as well.
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```typescript
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// app.module.ts
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import { Module } from '@nestjs/common';
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import { InMemoryDBModule } from '@nestjs-addons/in-memory-db';
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...
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@Module({
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...
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imports: [InMemoryDBModule],
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...
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})
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export class AppModule {}
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```
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As you can see we did the following:
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- Import `InMemoryDBModule` from `@nestjs-addons/in-memory-db`
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- Add `InMemoryDBModule` to the `imports` array in the `@Module` of your choice
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### Define an interface for each InMemoryEntity
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An instance of `InMemoryDBService<T>` will be created for each `InMemoryEntity` entity `interface` defined. The `InMemoryEntity` adds an `id: number` property as the only required field. Additional fields can be defined by extending the `interface`.
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To define a new `InMemoryEntity` extension create an `interface` similar to the following example:
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```typescript
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interface UserEntity extends InMemoryEntity {
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firstName: string;
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lastName: string;
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emailAddress: string;
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admin: boolean;
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}
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```
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Now we can make use of our new `interface` when injecting the `InMemoryDBService<T>` into our controllers or other services.
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### Inject into Controller(s) and/or Services(s)
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In order to use the `InMemoryDBService<T>` we need to do the following:
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- Add `private readonly inMemoryDb: InMemoryDBService<T>` to the `constructor` of each controller and/or service that you would like to use it in.
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- Begin using `InMemoryDBService` as expected.
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An example of injecting `InMemoryDBService` into a `UserController` for the `UserEntity` we defined earlier would look something like this:
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```typescript
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@Controller()
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export class UserController {
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constructor(private readonly userService: InMemoryDBService<UserEntity>) {}
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@Get('users/:id')
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getUser(@Param() id: number): User {
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return this.userService.get(id);
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}
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@Post('users')
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createUser(@Body() user: User): User {
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return this.service.create(user);
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}
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}
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```
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## API Documentation
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### `InMemoryDBService<T extends InMemoryEntity>`
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This is the service that provides the in-memory database. All methods interact with a `records` array and implement `generics` to provide type-safety and intellisense based on the `T extends InMemoryEntity` passed in.
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#### Public Methods
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**`public create(record: Partial<T>): number`**
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This method takes in a `Partial<T>` as we do not always know the `id` for a record when we are creating. If we leave off the `id` property the service will automatically generate an `id` for us. Upon successful creation, the method returns the generated `id`.
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Example Usage:
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```typescript
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const newUserId = this.userService.create({
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firstName: 'Some',
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lastName: 'Person',
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});
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console.log({ newUserId });
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// logs out
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// {
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// newUserId: 1
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// }
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```
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**`public update(record: T): void`**
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This method takes in a `T` record object and updates the record in the `records` array based on the `id` in the object. This method does not return a value.
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Example Usage:
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```typescript
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this.userService.update({
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id: 1,
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firstName: 'Other',
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lastName: 'Person',
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});
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```
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**`public delete(id: number): void`**
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This method takes in a `id: number` and deletes the record from the `records` array based on the `id` in the object. This method does not return a value.
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Example Usage:
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```typescript
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this.userService.delete(1);
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```
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**`public get(id: number): T`**
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This method takes in a `id: number` and returns the record from the `records` array based on the `id` in the object.
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Example Usage:
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```typescript
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const foundUser = this.userService.get(1);
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console.log({ foundUser });
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// logs out
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// {
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// foundUser: {
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// id:1,
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// firstName: 'Some',
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// lastName: 'Person'
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// }
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// }
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```
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**`public getAll(): T[]`**
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This method has no parameters and returns the all from the `records` array.
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Example Usage:
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```typescript
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const allUsers = this.userService.getAll();
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console.log({ allUsers });
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// logs out
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// {
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// allUsers: [
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// {
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// id: 1,
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// firstName: 'Some',
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// lastName: 'Person'
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// },
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// {
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// id: 2,
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// firstName: 'Other',
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// lastName: 'Person'
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// }
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// ];
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// }
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```
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**`public query(predicate: (record: T) => boolean): T[]`**
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This method has takes in a `record: T` predicate and returns all from the `records` array that meet that predicate's requirements.
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Example Usage:
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```typescript
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const foundUsers = this.userService.query(
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record => record.lastName === 'Person',
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);
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console.log({ foundUsers });
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// logs out
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// {
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// allUsers: [
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// {
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// id: 1,
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// firstName: 'Some',
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// lastName: 'Person'
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// },
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// {
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// id: 2,
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// firstName: 'Other',
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// lastName: 'Person'
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// }
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// ];
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// }
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```
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#### Public Properties
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- `records: T[]` - This is the in-memory array used in all crud and read operations for the service. Please access with care.
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### `InMemoryEntity`
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This is an interface used by the `InMemoryDBService` for intellisense and type-safety. Do not use this interface directly. Rather, implement your own `interface` that `extends` this.
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```typescript
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export interface InMemoryDBEntity {
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id: number;
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}
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```
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## Stay in touch
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‎index.ts

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export * from "./dist";
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export * from './dist';

‎lib/in-memory-db.module.ts

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import { Module } from "@nestjs/common";
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import { InMemoryDBService } from "./in-memory-db.service";
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import { Module } from '@nestjs/common';
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import { InMemoryDBService } from './in-memory-db.service';
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@Module({
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providers: [InMemoryDBService],
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exports: [InMemoryDBService]
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exports: [InMemoryDBService],
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})
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export class InMemoryDBModule {}

‎lib/in-memory-db.service.spec.ts

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import { InMemoryDBService } from "./in-memory-db.service";
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import { InMemoryDBEntity } from "./interfaces/in-memory-db-entity";
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import { InMemoryDBService } from './in-memory-db.service';
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import { InMemoryDBEntity } from './interfaces/in-memory-db-entity';
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describe("In Memory DB Service", () => {
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describe('In Memory DB Service', () => {
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interface TestEntity extends InMemoryDBEntity {
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someField: string;
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}
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let service: InMemoryDBService<TestEntity>;
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const sampleRecords: TestEntity[] = [
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{ id: 1, someField: "AAA" },
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{ id: 2, someField: "BBB" }
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{ id: 1, someField: 'AAA' },
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{ id: 2, someField: 'BBB' },
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];
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beforeEach(() => {
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service = new InMemoryDBService<TestEntity>();
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});
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describe("get", () => {
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it("should return expected record if given valid id", () => {
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describe('get', () => {
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it('should return expected record if given valid id', () => {
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// arrange
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service.records = [...sampleRecords];
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const expectedRecord = sampleRecords[0];
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expect(actualRecord).toEqual(expectedRecord);
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});
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it("should return undefined if given invalid id", () => {
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it('should return undefined if given invalid id', () => {
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service.records = [...sampleRecords];
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const expectedRecord = undefined;
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expect(actualRecord).toEqual(expectedRecord);
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});
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});
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describe("getAll", () => {
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it("should return all expected records", () => {
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describe('getAll', () => {
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it('should return all expected records', () => {
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// arrange
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service.records = [...sampleRecords];
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const expectedRecords = service.records;
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// assert
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expect(actualRecords).toEqual(expectedRecords);
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});
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it("should return empty array if no records", () => {
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it('should return empty array if no records', () => {
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// arrange
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service.records = [];
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const expectedRecords = [];
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expect(actualRecords).toEqual(expectedRecords);
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});
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});
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describe("create", () => {
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it("should update records with correct items", () => {
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describe('create', () => {
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it('should update records with correct items', () => {
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// arrange
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service.records = [];
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const itemToAdd: Partial<TestEntity> = { someField: "Test" };
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const itemToAdd: Partial<TestEntity> = { someField: 'Test' };
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const expectedRecords = [...[{ ...itemToAdd, id: 1 }]];
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// act
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// assert
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expect(actualRecords).toEqual(expectedRecords);
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});
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it('should return generated id', () => {
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// arrange
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service.records = [];
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const itemToAdd: Partial<TestEntity> = { someField: 'Test' };
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const expectedGeneratedId = 1;
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const expectedRecords = [...[{ ...itemToAdd, id: expectedGeneratedId }]];
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// act
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const actualGeneratedId = service.create(itemToAdd);
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// assert
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expect(actualGeneratedId).toEqual(expectedGeneratedId);
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});
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});
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describe("update", () => {
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it("should update record as expected", () => {
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describe('update', () => {
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it('should update record as expected', () => {
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// arrange
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const originalRecord: TestEntity = { id: 1, someField: "AAA" };
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const expectedUpdatedRecord: TestEntity = { id: 1, someField: "BBB" };
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const originalRecord: TestEntity = { id: 1, someField: 'AAA' };
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const expectedUpdatedRecord: TestEntity = { id: 1, someField: 'BBB' };
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service.records = [...[originalRecord]];
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// act
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service.update(expectedUpdatedRecord);
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const actualUpdatedRecord = service.records.find(
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record => record.id === originalRecord.id
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record => record.id === originalRecord.id,
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);
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expect(actualUpdatedRecord).toEqual(expectedUpdatedRecord);
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});
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});
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describe("delete", () => {
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it("should remove record as expected", () => {
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describe('delete', () => {
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it('should remove record as expected', () => {
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// arrange
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service.records = [
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{ id: 1, someField: "AAA" },
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{ id: 2, someField: "BBB" }
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{ id: 1, someField: 'AAA' },
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{ id: 2, someField: 'BBB' },
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];
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// act
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expect(service.records.length).toEqual(1);
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});
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});
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describe("query", () => {
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it("should return expected records for given predicate", () => {
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describe('query', () => {
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it('should return expected records for given predicate', () => {
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// arrange
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service.records = [
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{ id: 1, someField: "AAA" },
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{ id: 2, someField: "BBB" }
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{ id: 1, someField: 'AAA' },
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{ id: 2, someField: 'BBB' },
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];
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const expectedFoundRecord = [service.records[1]];
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// act
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const foundRecord = service.query(record => record.someField === "BBB");
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const foundRecord = service.query(record => record.someField === 'BBB');
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// assert
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expect(foundRecord).toEqual(expectedFoundRecord);

‎lib/in-memory-db.service.ts

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import { Injectable } from "@nestjs/common";
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import { InMemoryDBEntity } from "./interfaces/in-memory-db-entity";
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import { Injectable } from '@nestjs/common';
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import { InMemoryDBEntity } from './interfaces/in-memory-db-entity';
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@Injectable()
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export class InMemoryDBService<T extends InMemoryDBEntity> {
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public records: T[] = [];
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public create(record: Partial<T>): T {
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public create(record: Partial<T>): number {
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const id = record.id || this.getNextId();
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const newRecord: T = { ...record, id } as T;
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this.records.push(newRecord);
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return newRecord;
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return newRecord.id;
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}
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public update(record: T): void {

‎lib/index.ts

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export { InMemoryDBModule } from "./in-memory-db.module";
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export { InMemoryDBService } from "./in-memory-db.service";
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export { InMemoryDBEntity } from "./interfaces/in-memory-db-entity";
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export { InMemoryDBModule } from './in-memory-db.module';
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export { InMemoryDBService } from './in-memory-db.service';
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export { InMemoryDBEntity } from './interfaces/in-memory-db-entity';

‎lib/interfaces/index.ts

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export * from "./in-memory-db-entity";
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export * from './in-memory-db-entity';

‎package-lock.json

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‎package.json

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{
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"name": "@nestjs-addons/in-memory-db",
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"version": "0.0.1",
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"version": "0.0.2",
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"description": "Simple In-Memory DB Service for NestJS projects",
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"author": "Wes Grimes",
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"license": "MIT",

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