json.md

JSON

Content-Type: "application/json"

The Context.JSON(v, ...opts) is the method which sends JSON responses to the client. It accepts the value and optional settings for rendering. The JSON options structure looks like this:

// JSON contains the options for the JSON (Context's) Renderer.
type JSON struct {
	// http-specific
	StreamingJSON bool
	// content-specific
	UnescapeHTML bool
	Indent       string
	Prefix       string
    ASCII        bool
    // if true then it prepends a "while(1);" when Go slice (to JSON Array) value.
	Secure       bool
	// proto.Message specific marshal options.
	Proto ProtoMarshalOptions
}

If Indent field is empty and the application runs without optimizations, the Indent field will be automatically set to 2 spaces.

So, if we want to write a JSON with indentation of four spaces and prefixed with while(1) we can do something like that:

func handler(ctx iris.Context) {
    response := map[string]interface{}{"message": "ok"}
    options := iris.JSON{Indent: "    ", Secure:true}
    ctx.JSON(response, options)
}

Result

{
    "message": "ok"
}

As with all RESTful rich responses, any marshallable (JSON at this case) Go type can be given. If we want to render a Go struct as JSON, the struct's fields we want to render should be exported, and optionally tagged with the json struct tag. Look the exaple below:

type User struct {
    Firstname    string `json:"firstname"`
    Lastname     string `json:"lastname"`
    IgnoredField int    `json:"-"`
}

func handler(ctx iris.Context) {
    response := User{
        Firstname: "makis",
        Lastname: "maropoulos",
        IgnoredField:42,
    }

    ctx.JSON(response)
}

Result

{
  "firstname": "makis",
  "lastname": "maropoulos"
}