Calling REST API Using GoLang: Hands-On

Creating a HTTP Client to perform requests

Let's create a simple file that will be used to make HTTP request:

internal/httpclient/httpclient.go

package httpclient

import (
    "bytes"
    "encoding/json"
    "net/http"
)

func Post(url string, body interface{}) (*http.Response, error) {

    marshal, err := json.Marshal(body)
    if err != nil {
        panic(any(err))
    }

    byteArr := []byte(marshal)

    return http.Post(url, "application/json", bytes.NewBuffer(byteArr))

}

Creating the application responsible for Application

This module contain all things about application.

Let's get the implementation:

internal/application/application.go

package application

import (
    "log"
    "net/http"

    "github.com/mcruzdev/platformoon-cli/internal/httpclient"
)

type ApplicationRequest struct {
    Name       string `json:"name"`
    Type       string `json:"type"`
    Technology string `json:"technology"`
}

func NewApplicationRequest(name, appType, technology string) *ApplicationRequest {
    return &ApplicationRequest{
        Name:       name,
        Technology: technology,
        Type:       appType,
    }
}

func CreateNewApplication(name, appType, technology string) {
    ar := NewApplicationRequest(name, appType, technology)
    r, err := httpclient.Post("http://localhost:8080/applications", ar)

    if err != nil {
        panic(any(err))
    }

    if r.StatusCode == http.StatusCreated {
        log.Printf("Application created: %s", r.Header["Location"])
    }
}

Change application create command

Finally, let's change the handle for platformoon application create command:

cmd/platformoon/platformoon.go

func NewApplicationCreateCmd() *cobra.Command {
    var cmd = &cobra.Command{
        Use:   "create",
        Short: "This command is used to create a new application",
        Run: func(cmd *cobra.Command, args []string) {
            log.Println("platformoon application create works")
            application.CreateNewApplication("application", "API", "JAVA") // (1)
        },
    }

    return cmd
}

1. This values are hard-coded, we will change it later.

Calling the REST API

Now, that all things are okay, let's execute our CLI:

Note

Check if the REST API is running.

go run cmd/platformoon/platformoon.go application create

The output should looks something like it:

2023/10/27 22:44:54 platformoon application create works
2023/10/27 22:44:54 Application created: [http://localhost:8080/applications/06ce9936-4a74-4328-b2f7-f4e40e310706]

Thank you!

Done! The next step is to add parameters to the CLI, follow this tutorial to do it.