介绍

There is an example project for you to play with.

Setup

Launch database

cd example/database
docker-compose up # this will launch the database

The user name, password, database are all "test"; port number is 6666.

You can also use your own database instead of this docker. In that case, remember to update the database configuration here.

Launch grapqhql api server

cd example
npm install
npm run seed # this will seed the data
npm start

注意

COMPATIBILITY NOTE: This example code requires Node.js >= 12.

You should be able to access the graphql playground on http://localhost:4000/

Try query in the playground

Run the following graphql query.

query {
  queryPost(
    where: { id: { gt: 1 } }
    offset: 0
    limit: 3
    orderBy: { column: "id", order: "asc" }
  ) {
    id
    title
    author {
      email
      company {
        domain
      }
    }
  }
}

You should be able to see result similar to the following.

{
  "data": {
    "queryPost": [
      {
        "id": 2,
        "title": "new post 2222",
        "author": [
          {
            "email": "ur@moej.wf",
            "company": [
              {
                "domain": "nouco.cn"
              }
            ]
          }
        ]
      },
      {
        "id": 3,
        "title": "Gokgor kezli lazgoh gaw nite mewseun do supma.",
        "author": [
          {
            "email": "vilurazu@vuse.tk",
            "company": [
              {
                "domain": "nitdopfiz.ro"
              }
            ]
          }
        ]
      },
      {
        "id": 4,
        "title": "Totunusa kazaha ruguk di zuvon mojfogow datiha ewa.",
        "author": [
          {
            "email": "ur@moej.wf",
            "company": [
              {
                "domain": "nouco.cn"
              }
            ]
          }
        ]
      }
    ]
  }
}

Let's check the queries excuted

In the backend, only 1 queries is executed. We will explain more details about how N+1 problems is avoided in the library.

> nodemon example/index.js

[nodemon] 2.0.2
[nodemon] to restart at any time, enter `rs`
[nodemon] watching dir(s): *.*
[nodemon] watching extensions: js,mjs,json
[nodemon] starting `node example/index.js`
🚀  Server ready at http://localhost:4000/ 
----------  SEARCH QUERY (Post) ---------
 select "posts"."id" as "crud_base___id", "posts"."title" as "crud_base___title", "posts"."author_id" as "crud_base___author_id", "authors"."email" as "authors___email", "authors"."id" as "authors___id", "companies"."domain" as "companies___domain", "companies"."id" as "companies___id" from "posts" left join "authors" on "posts"."author_id" = "authors"."id" left join "companies" on "authors"."company_id" = "companies"."id" where "posts"."id" > 1 order by "posts"."id" asc limit 3