Basic API example

base-api.controller.ts

import { Connection } from "typeorm";

export abstract class BaseApiController<T> {
    protected classType: new () => T;

    public static connection: Connection;

    constructor(classType: new () => T) {
        this.classType = classType;
    }

    public async find(): Promise<T[]> {
        return await BaseApiController.connection.manager.find(this.classType);
    }

    public async save(entity: T): Promise<T> {
        console.dir(entity);
        return await BaseApiController.connection.manager.save(entity);
    }
}

user.controller.ts

import {
    BaseApiController,
} from '../controllers';

import {
    User,
} from '../entity';

import {
    JsonController,
    Get,
    Post,
    Body,
} from 'routing-controllers';

@JsonController('/user')
export class UserController extends BaseApiController<User> {
    constructor() {
        super(User)
    }

    @Get()
    public async find(): Promise<User[]> {
        return super.find();
    }

    @Post()
    public async save(
        @Body() user: User,
    ): Promise<User> {
        return super.save(user);
    }
}