gofr-dev/gofr

# Custom Response Headers and Metadata in GoFr
 
GoFr simplifies the process of adding custom HTTP response headers and metadata to API responses using the `Response` struct. This feature allows you to include additional information such as custom headers or metadata to enhance client-server communication while keeping your data payload clean and structured.
 
## Features
 
1. **Custom Headers**: Add key-value pairs for headers, useful for:
    - Security policies
    - Debugging information
    - Versioning details
 
   **Type**: `map[string]string`
    - Keys and values must be strings.
 
2. **Metadata**: Include optional contextual information like:
    - Deployment environment
    - Request-specific details (e.g., timestamps, tracing IDs)
 
   **Type**: `map[string]any`
    - Keys must be strings, and values can be of any type.
 
When metadata is included, the response structure is:
 
```json
{
  "data": {},
  "metadata": {}
}
```
 
If metadata is omitted, the response defaults to:
 
```json
{
  "data": {}
}
```
 
### Example Usage
 
#### Adding Custom Headers and Metadata
To include custom headers and metadata in your response, populate the Headers and MetaData fields of the Response struct in your handler function.
 
```go
package main
 
import (
    "time"
 
    "gofr.dev/pkg/gofr"
    "gofr.dev/pkg/gofr/http/response"
)
 
func main() {
    app := gofr.New()
 
    app.GET("/hello", HelloHandler)
 
    app.Run()
}
 
func HelloHandler(c *gofr.Context) (any, error) {
    name := c.Param("name")
    if name == "" {
        c.Log("Name parameter is empty, defaulting to 'World'")
        name = "World"
    }
 
    // Define custom headers (map[string]string)
    headers := map[string]string{
        "X-Custom-Header":  "CustomValue",
        "X-Another-Header": "AnotherValue",
    }
 
    // Define metadata (map[string]any)
    metaData := map[string]any{
        "environment": "staging",
        "timestamp":   time.Now(),
    }
 
    // Return response with custom headers and metadata
    return response.Response{
        Data:     map[string]string{"message": "Hello, " + name + "!"},
        Metadata: metaData,
        Headers:  headers,
    }, nil
}
```
 
### Example Responses
#### Response with Metadata:
When metadata is included, the response contains the metadata field:
 
```json
{
  "data": {
    "message": "Hello, World!"
  },
  "metadata": {
    "environment": "staging",
    "timestamp": "2024-12-23T12:34:56Z"
  }
}
```
 
#### Response without Metadata:
If no metadata is provided, the response only includes the data field:
 
```json
{
  "data": {
    "message": "Hello, World!"
  }
}
```
 
 
This functionality offers a convenient, structured way to include additional response information without altering the 
core data payload.