Building a Simple REST API in Go with Gin

In this post, we'll explore building a basic REST API using Go and the Gin framework. We'll walk through the code, understand the concepts, and see how to store and retrieve key-value pairs.

Prerequisites:

• Basic understanding of Go programming
• Familiarity with HTTP concepts

What you'll learn:

• Creating a REST API with Gin
• Storing and retrieving data using key-value pairs
• JSON data formatting

Code Snippet:

package main

import (
    "encoding/json"
    "fmt"
    "github.com/gin-gonic/gin"
)

var store map[string]string

func main() {
    store = make(map[string]string)
    router := gin.Default()

    router.POST("/key", func(c *gin.Context) {
        key := c.Param("key")
        value := c.PostForm("value")

        store[key] = value
        c.JSON(200, gin.H{"message": "Stored"})
    })

    router.GET("/key/:key", func(c *gin.Context) {
        key := c.Param("key")
        value, ok := store[key]

        if !ok {
            c.JSON(404, gin.H{"message": "Not found"})
            return
        }

        var unmarshaledValue map[string]interface{}
        err := json.Unmarshal([]byte(value), &unmarshaledValue)
        if err != nil {
            c.JSON(500, gin.H{"message": "Error unmarshaling value"})
            return
        }

        c.JSON(200, unmarshaledValue)
    })

    router.Run()
}

Explanation:

Import Libraries:

• encoding/json: For JSON data encoding and decoding.
• fmt: For output formatting.
• github.com/gin-gonic/gin: The Gin framework for web applications.

Define Map:

• store: A map[string]string to store key-value pairs.

Create Gin Router:

• router: A Gin router instance to handle HTTP requests.

Store Key-Value Pairs:

• POST /key: Handles POST requests to store data.
• It retrieves the key from the URL path and value from the request body.
• Stores the pair in the store map and returns a "Stored" message.

Retrieve Key-Value Pairs:

• GET /key/:key: Handles GET requests to retrieve data.
• The :key part captures the key from the URL path.
• Retrieves the value for the specified key from the store map.
• Returns a 404 Not Found if the key isn't found.
• Otherwise, unmarshals the JSON-encoded value and returns it.

Run the Server:

• router.Run(): Starts the Gin server and listens for requests.

Summary:

This code demonstrates building a simple REST API in Go with Gin. It allows storing and retrieving key-value pairs in JSON format.

I hope this helps! Feel free to ask any questions you may have.

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