Go JSON/YAML Formatter

This is a simple command-line tool built in Go that reads a messy or minified JSON or YAML file and prints a clean, pretty, and colorized version to the terminal.

It automatically detects the file type (.json, .yml, or .yaml) and formats it accordingly.

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✨ Features

• Formats both JSON and YAML files.
• Automatically detects the file type based on its extension.
• Pretty-prints the output with standard indentation.
• Colorizes the output for better readability:
  • Cyan for JSON
  • Magenta for YAML
• Validates the file content and reports errors for invalid formats.

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🚀 How to Run

Prerequisites

• Go (Version 1.18 or newer)

1. Set Up the Project

1. In your project directory, initialize the Go module:

   go mod init go-formatter

2. Install the required dependencies:

   go get gopkg.in/yaml.v3
   go get github.com/fatih/color

2. Run the Formatter

Use go run . followed by the name of the file you want to format.

Example: Formatting JSON

1. Create a file messy.json:

   {"name":"John","age":30,"isStudent":false,"courses":[{"title":"History","credits":3}],"address":null}

2. Run the tool:

   go run . messy.json

3. Output (in Cyan):

   {
     "address": null,
     "age": 30,
     "courses": [
       {
         "credits": 3,
         "title": "History"
       }
     ],
     "isStudent": false,
     "name": "John"
   }

Example: Formatting YAML

1. Create a file messy.yaml:

   name: Jane
   age: 28
   isStudent: true
   courses:
     - title: Math
       credits: 4
     - title: Physics
       credits: 5
   address:
     street: 123 Main St
     city: Anytown

2. Run the tool:

   go run . messy.yaml

3. Output (in Magenta):

   name: Jane
   age: 28
   isStudent: true
   courses:
       - title: Math
         credits: 4
       - title: Physics
         credits: 5
   address:
       street: 123 Main St
       city: Anytown

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🛠️ (Bonus) Build the Executable

To use this like a real command-line tool without typing go run every time, you can build the binary:

# This creates an executable file (e.g., 'format' or 'format.exe')
go build -o format

Now you can run it directly from that folder:

./format messy.json

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🧠 Key Concepts

• os.Args: Used to read command-line arguments (specifically, the filename provided by the user).
• os.ReadFile: Reads the raw byte content of the specified file.
• filepath.Ext: Used to detect the file type by checking its extension.
• json.Unmarshal / yaml.Unmarshal: Parses the raw bytes into a generic interface{}, which can hold any data structure.
• json.MarshalIndent / yaml.Marshal: Re-serializes the interface{} back into a "pretty" byte slice. json.MarshalIndent is used to add indentation, while the yaml.v3 library formats nicely by default.
• github.com/fatih/color: A third-party library used to wrap the output string in ANSI color codes for a better terminal experience.