Go ORM example application

The following tutorial implements an ORM example using GORM, the ORM library for Golang, that implements a basic REST API server. The scenario is that of an e-commerce application. Database access in this application is managed using GORM.

The source for the above application can be found in the repository. There are a number of options that can be customized in the properties file located at src/config/config.json.

Prerequisites

This tutorial assumes that you have:

  • YugabyteDB up and running. Download and install YugabyteDB by following the steps in Quick start.
  • Go 1.8, or later, is installed. The latest releases are available on the Go Downloads page.

Go dependencies

To install the required Go dependencies, run the following commands.

go get github.com/jinzhu/gorm
go get github.com/jinzhu/gorm/dialects/postgres
go get github.com/google/uuid
go get github.com/gorilla/mux
go get github.com/lib/pq
go get github.com/lib/pq/hstore

Clone the "orm-examples" repository

Clone the Yugabyte orm-examples repository by running the following command.

$ git clone https://github.com/YugabyteDB-Samples/orm-examples.git

Run the following export command to specify the GOPATH environment variable.

export GOPATH=$GOPATH:$HOME/orm-examples/golang/gorm

Build and run the application

Change to the gorm directory.

$ cd ./golang/gorm

Create the ysql_gorm database in YugabyteDB by running the following ysqlsh command from the YugabyteDB home directory.

$ ./bin/ysqlsh -c "CREATE DATABASE ysql_gorm"

Build and start the REST API server by running the following shell script.

$ ./build-and-run.sh

The REST API server will start and listen for requests at http://localhost:8080.

Send requests to the application

Create 2 users.

$ curl --data '{ "firstName" : "John", "lastName" : "Smith", "email" : "jsmith@example.com" }' \
   -v -X POST -H 'Content-Type:application/json' http://localhost:8080/users

$ curl --data '{ "firstName" : "Tom", "lastName" : "Stewart", "email" : "tstewart@example.com" }' \
   -v -X POST -H 'Content-Type:application/json' http://localhost:8080/users

Create 2 products.

$ curl \
  --data '{ "productName": "Notebook", "description": "200 page notebook", "price": 7.50 }' \
  -v -X POST -H 'Content-Type:application/json' http://localhost:8080/products

$ curl \
  --data '{ "productName": "Pencil", "description": "Mechanical pencil", "price": 2.50 }' \
  -v -X POST -H 'Content-Type:application/json' http://localhost:8080/products

Create 2 orders.

$ curl \
  --data '{ "userId": "2", "products": [ { "productId": 1, "units": 2 } ] }' \
  -v -X POST -H 'Content-Type:application/json' http://localhost:8080/orders

$ curl \
  --data '{ "userId": "2", "products": [ { "productId": 1, "units": 2 }, { "productId": 2, "units": 4 } ] }' \
  -v -X POST -H 'Content-Type:application/json' http://localhost:8080/orders

Query results

Using the YSQL shell

$ ./bin/ysqlsh

ysqlsh (11.2)
Type "help" for help.

yugabyte=#

yugabyte=# SELECT count(*) FROM users;

 count
-------
     2
(1 row)

yugabyte=# SELECT count(*) FROM products;

 count
-------
     2
(1 row)

yugabyte=# SELECT count(*) FROM orders;

 count
-------
     2
(1 row)

Using the REST API

$ curl http://localhost:8080/users

{
  "content": [
    {
      "userId": 2,
      "firstName": "Tom",
      "lastName": "Stewart",
      "email": "tstewart@example.com"
    },
    {
      "userId": 1,
      "firstName": "John",
      "lastName": "Smith",
      "email": "jsmith@example.com"
    }
  ],
  ...
}

$ curl http://localhost:8080/products

{
  "content": [
    {
      "productId": 2,
      "productName": "Pencil",
      "description": "Mechanical pencil",
      "price": 2.5
    },
    {
      "productId": 1,
      "productName": "Notebook",
      "description": "200 page notebook",
      "price": 7.5
    }
  ],
  ...
}

$ curl http://localhost:8080/orders

{
  "content": [
    {
      "orderTime": "2019-05-10T04:26:54.590+0000",
      "orderId": "999ae272-f2f4-46a1-bede-5ab765bb27fe",
      "user": {
        "userId": 2,
        "firstName": "Tom",
        "lastName": "Stewart",
        "email": "tstewart@example.com"
      },
      "userId": null,
      "orderTotal": 25,
      "products": []
    },
    {
      "orderTime": "2019-05-10T04:26:48.074+0000",
      "orderId": "1598c8d4-1857-4725-a9ab-14deb089ab4e",
      "user": {
        "userId": 2,
        "firstName": "Tom",
        "lastName": "Stewart",
        "email": "tstewart@example.com"
      },
      "userId": null,
      "orderTotal": 15,
      "products": []
    }
  ],
  ...
}