OData V4 Service modules - TYPEORM Connector

Service OData v4 requests from a TYPEORM.

Synopsis

The OData V4 TYPEORM Connector provides functionality to convert the various types of OData segments into SQL query statements, that you can execute over a TYPEORM.

Potential usage scenarios

• Create high speed, standard compliant data sharing APIs

Usage as server - TypeScript

example request: GET /api/users?$filter=id eq 42&$select=id,name

NestJS middleware

- middleware

import { Inject, Injectable, NestMiddleware } from '@nestjs/common';
import { Request, Response } from 'express';
import { odataQuery } from 'odata-v4-typeorm';
import { Repository } from 'typeorm';

import { UserEntity } from '../entities/user.entity';

@Injectable()
export class OdataUsersMiddleware implements NestMiddleware {
  constructor(
    @Inject('USERS_REPOSITORY') private readonly usersRepository: Repository<UserEntity>
  ) {}

  use(req: Request, res: Response, next: Function) {
    odataQuery(this.usersRepository)(req, res, next);
  }
}

users repository provider

import { Connection } from 'typeorm';
import { UserEntity } from '../user.entity';

export const userProviders = [
  {
    provide: 'USERS_REPOSITORY',
    useFactory: (connection: Connection) => connection.getRepository(UserEntity),
    inject: ['DATABASE_CONNECTION'],
  }
];

database provider

import { createConnection } from 'typeorm';
import { UserEntity } from '../entities/user.entity';

export const databaseProviders = [
  {
    provide: 'DATABASE_CONNECTION',
    useFactory: async () => await createConnection({
      type: 'postgres',
      host: 'localhost',
      port: 3306,
      username: 'postgres',
      password: 'root',
      database: 'test',
      synchronize: true,
      
      entities: [UserEntity]
    }),
  },
];

app module

import { MiddlewareConsumer, Module, NestModule } from '@nestjs/common';

import { databaseProviders } from './db/database.providers';
import { userProviders } from './providers/user.providers';
import { OdataUsersMiddleware } from './middlewares/odataUsers.middleware';

@Module({
  providers: [
    ...databaseProviders,
    ...userProviders,
  ],
})
export class AppModule implements NestModule {
  configure(consumer: MiddlewareConsumer) {
    consumer
      .apply(OdataUsersMiddleware)
      .forRoutes('api/v1/odata/users');
  }
}

odataQuery

import express from 'express';
import { odataQuery } from 'odata-v4-typeorm';
import { getRepository } from 'typeorm';
import { User } from '../entities/user';

const app = express();
const usersRepository = getRepository(User);

app.get('/api/users', odataQuery(usersRepository));

const port = 3001;
app.listen(port, () => console.log(`Example app listening on port ${port}!`));

executeQuery by repository

import express from 'express';
import { executeQuery } from 'odata-v4-typeorm';
import { getRepository } from 'typeorm';
import { User } from '../entities/user';

const app = express();

app.get('/api/users', async (req, res) => {
  try {
    const usersRepository = getRepository(User);
    const data = await executeQuery(usersRepository, req.query);
    return res.status(200).json(data);
  } catch (e) {
    return res.status(500).json({message: 'Internal server error.'});
  }
});

const port = 3001;
app.listen(port, () => console.log(`Example app listening on port ${port}!`));

executeQuery by queryBuilder

import express from 'express';
import { executeQuery } from 'odata-v4-typeorm';
import { getRepository } from 'typeorm';
import { User } from '../entities/user';

const app = express();

app.get('/api/users', async (req, res) => {
  try {
    const queryBuilder = getRepository(User)
      .createQueryBuilder("user")
      .where("user.roleName = :roleName", { roleName: 'admin' });
    const data = await executeQuery(queryBuilder, req.query);
    return res.status(200).json(data);
  } catch (e) {
    return res.status(500).json({message: 'Internal server error.'});
  }
});

const port = 3001;
app.listen(port, () => console.log(`Example app listening on port ${port}!`));

createFilter

import { createFilter } from 'odata-v4-typeorm'

//example request:  GET /api/Users?$filter=Id eq 42
app.get("/api/Users", (req: Request, res: Response) => {
    const filter = createFilter(req.query.$filter);
    // connection instance from pg module
    connection.query(`SELECT * FROM Users WHERE ${filter.where}`, filter.parameters, function(err, result){
        res.json({
        	'@odata.context': req.protocol + '://' + req.get('host') + '/api/$metadata#Users',
        	value: result.rows
        });
    });
});

Advanced TypeScript example available here.

Usage ES5

var createFilter = require('odata-v4-typeorm').createFilter;

app.get("/api/Users", function(req, res) {
    var filter = createFilter(req.query.$filter);
    // connection instance from pg module
    connection.query(filter.from("Users"), filter.parameters, function(err, result){
        res.json({
        	'@odata.context': req.protocol + '://' + req.get('host') + '/api/$metadata#Users',
        	value: result.rows
        });
    });
})

Supported OData segments

• $filter
• $select
• $skip
• $top
• $orderby
• $expand
• $count

If you have any questions, please don’t hesitate to contact me.

• skype: andryuha49.
• https://www.linkedin.com/in/andriy-zherdiy/