# Output

Beego provides a variety of APIs to help users export to the client, supporting several data formats such as JSON, XML or YAML.

These methods are mainly defined on Controller and Context.

For example, WriteString：

ctrl.Ctx.WriteString("Hello")

# Controller Serve

Controller has a number of Serve methods that can be used to output JSON, XML or YAML data.

The Serve class method is used in two steps: first, setting up the Data, and second, refreshing to the front-end.

JSON：
```
func (this *AddController) Get() {
	mystruct := { ... }
	this.Data["json"] = &mystruct
	this.ServeJSON()
}
```
When ServeJSON is called, content-type is set to application/json, and the data is output JSON serialized at the same time.

XML:

func (this *AddController) Get() {
	mystruct := { ... }
	this.Data["xml"]=&mystruct
	this.ServeXML()
}

After calling ServeXML, the content-type is set to application/xml, and the data is serialized for XML output.

jsonp
```
func (this *AddController) Get() {
	mystruct := { ... }
	this.Data["jsonp"] = &mystruct
	this.ServeJSONP()
}
```
After calling ServeJSONP, the content-type is set to application/javascript, and then the data is JSON serialized at the same time, and then the jsonp output is set according to the callback parameter of the request.

# Based On Accept Header

In general, we do recommend that the backend directly specify the format of the response data. For example, using JSON format directly as data input and output inside an application.

But there are times when we have to be compatible with multiple data formats, so consider using the SetData method and the ServeFormatted method. For example:

func (this *AddController) Get() {
    mystruct := { ... }
    this.SetData(&mystruct)
    this.ServeFormatted()
}

Both are based on the Accept header field in the HTTP request to infer what format of data should be output as a response. If there is no Accept header, or if the field cannot be parsed, JSON formatted data will be output by default.

# Context Methods

If a functional routing style is used, that means we don't have a Controller to use. This is the time to consider using the methods on Context.

Example:

func (this *AddController) Get() {
    mystruct := { ... }
    this.Ctx.JSONResp(&mystruct)
}

These methods all take an interface as input and try to serialize the input. That is, if the input is a string, then the WriteString method should be considered.

JSONResp(data interface{}) error
YamlResp(data interface{}) error
ProtoResp(data proto.Message)
XMLResp(data interface{}) error

# Based On Accept Header

If you want to output response data based on the Accept field inside the HTTP request, then you should use the Resp method:

func (this *AddController) Get() {
    mystruct := { ... }
    this.Ctx.Resp(&mystruct)
}

If there is no Accept header, or if it cannot be parsed, then the data will be output using JSON.