The following tutorial implements an ORM example using [GORM](https://gorm.io/), 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](https://github.com/yugabyte/orm-examples/tree/master/golang/gorm). 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](/stable/quick-start/macos/).
- Go 1.21, or later, is installed. The latest releases are available on the [Go Downloads page](https://golang.org/dl/).
## Clone the "orm-examples" repository
Clone the Yugabyte [`orm-examples` repository](https://github.com/yugabyte/orm-examples) by running the following command.
```sh
$ git clone https://github.com/YugabyteDB-Samples/orm-examples.git
```
## Set up the application and install dependencies
Initialize Go within the project:
```sh
cd golang/gorm
go mod init gorm-example
```
Download the included packages and dependencies:
```sh
go mod tidy
```
## Build and run the application
Create the `ysql_gorm` database in YugabyteDB by running the following ysqlsh command from the YugabyteDB home directory.
```sh
$ ./bin/ysqlsh -c "CREATE DATABASE ysql_gorm"
```
Build and start the REST API server by running the following shell script. The application uses the [YugabyteDB smart driver for Go](https://github.com/yugabyte/pgx), which provides the connection load balancing feature.
Note: The application also works with the upstream Go driver (jackc/pgx). To use it, replace `github.com/yugabyte/gorm-yugabytedb` with `gorm.io/driver/postgres` in the application code.
```sh
$ ./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.
```sh
$ curl --data '{ "firstName" : "John", "lastName" : "Smith", "email" : "jsmith@example.com" }' \
-v -X POST -H 'Content-Type:application/json' http://localhost:8080/users
```
```sh
$ 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.
```sh
$ curl \
--data '{ "productName": "Notebook", "description": "200 page notebook", "price": 7.50 }' \
-v -X POST -H 'Content-Type:application/json' http://localhost:8080/products
```
```sh
$ 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.
```sh
$ curl \
--data '{ "userId": 2, "products": [ { "productId": 1, "units": 2 } ] }' \
-v -X POST -H 'Content-Type:application/json' http://localhost:8080/orders
```
```sh
$ 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
```sh
$ ./bin/ysqlsh
```
```output
ysqlsh (15.2-YB-{{}}-b0)
Type "help" for help.
yugabyte=#
```
```plpgsql
yugabyte=# SELECT count(*) FROM users;
```
```output
count
-------
2
(1 row)
```
```plpgsql
yugabyte=# SELECT count(*) FROM products;
```
```output
count
-------
2
(1 row)
```
```plpgsql
yugabyte=# SELECT count(*) FROM orders;
```
```output
count
-------
2
(1 row)
```
### Using the REST API
```sh
$ curl http://localhost:8080/users
```
```output.json
{
"content": [
{
"userId": 2,
"firstName": "Tom",
"lastName": "Stewart",
"email": "tstewart@example.com"
},
{
"userId": 1,
"firstName": "John",
"lastName": "Smith",
"email": "jsmith@example.com"
}
],
...
}
```
```sh
$ curl http://localhost:8080/products
```
```output.json
{
"content": [
{
"productId": 2,
"productName": "Pencil",
"description": "Mechanical pencil",
"price": 2.5
},
{
"productId": 1,
"productName": "Notebook",
"description": "200 page notebook",
"price": 7.5
}
],
...
}
```
```sh
$ curl http://localhost:8080/orders
```
```output.json
{
"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": []
}
],
...
}
```