Transformer

import "github.com/go-mizu/mizu/middlewares/transformer"

app := mizu.New()

// Transform request JSON
app.Use(transformer.Request(func(data map[string]any) map[string]any {
    // Rename field
    data["user_name"] = data["username"]
    delete(data, "username")
    return data
}))

app.Use(transformer.Request(func(data map[string]any) map[string]any {
    // Snake case to camel case
    if v, ok := data["first_name"]; ok {
        data["firstName"] = v
        delete(data, "first_name")
    }
    return data
}))

app.Use(transformer.Response(func(data map[string]any) map[string]any {
    // Add metadata
    return map[string]any{
        "data":    data,
        "version": "2.0",
    }
}))

fieldMap := map[string]string{
    "userName": "username",
    "firstName": "first_name",
    "lastName": "last_name",
}

app.Use(transformer.WithFieldMap(fieldMap))

// v1 to v2 transformation
app.Use(transformer.Request(func(data map[string]any) map[string]any {
    // v1 had "name", v2 expects "fullName"
    if name, ok := data["name"]; ok {
        data["fullName"] = name
        delete(data, "name")
    }
    return data
}))

// Request creates request transformer
func Request(fn func(map[string]any) map[string]any) mizu.Middleware

// Response creates response transformer
func Response(fn func(map[string]any) map[string]any) mizu.Middleware

// WithFieldMap creates field mapping transformer
func WithFieldMap(fieldMap map[string]string) mizu.Middleware