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Build a Go application

The following tutorial implements an ORM example using GORM, the ORM library for Golang, that implements a simple REST API server. The scenario is that of an e-commerce application. Database access in this application is managed using GORM. The e-commerce database (ysql_gorm) includes the following tables:

users table — the users of the e-commerce site
products table — the products being sold
orders table — the orders placed by the users
orderline table — each line item of an order

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.

Before you begin

This tutorial assumes that you have satisfied the following prerequisites.

YugabyteDB

YugabyteDB is up and running. If you are new to YugabyteDB, you can have YugabyteDB up and running within five minutes by following the steps in Quick start.

Go

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/yugabyte/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": []
    }
  ],
  ...
}

Explore the source

As mentioned earlier, the source for this application can be found in the Yugabyte orm-examples repository.