Resource Handler

The handler is an important part of the resource. It does the main business logic of the resource. The handler function takes the following parameters:

Context

The context object contains information about the request, It implements the fs.Context interface.

You can use the context object to access information about the request, such as the requesting user, request parameters, and request body.

type Context interface {
	context.Context
	TraceID() string
	User() *User
	Local(string, ...any) (val any)
	Logger() logger.Logger
	Bind(any) error
	Args() map[string]string
	Arg(string, ...string) string
	ArgInt(string, ...int) int
	Payload() (*schema.Entity, error)
	Resource() *Resource
	AuthToken() string
	Next() error
	Result(...*Result) *Result
	Files() ([]*File, error)
	Redirect(string) error
	WSClient() WSClient
}

Input

A POST or PUT request may contain a payload, FastSchema will automatically parse the payload into the Input struct.

The input parameter will be nil in the following cases:

The request is not a POST or PUT request.
The request payload is an empty object {}.
We decide to ignore the payload by using any as the input type: func(c fs.Context, _ any) (Output, error)

Content-Type

FastSchema will only parse the request payload if the Content-Type header is set to application/json.

If FastSchema cannot parse the payload into the Input struct, it will return an error and the handler will not be called.

Output

The handler function should return an Output and an error. The Output value will be serialized as JSON and sent back to the client.

The Output can be any type, including a primitive type, a struct, etc.

Send HTML response

resource := fs.Get("/about", func(c fs.Context, _ any) (string, error) {
	header := make(http.Header)
	header.Set("Content-Type", "text/html")

	return &fs.HTTPResponse{
		StatusCode: http.StatusOK,
		Header:     header,
		Body: []byte(`
			<!DOCTYPE html>
			<html>
			<head>
				<title>About</title>
			</head>
			<body>
				<h1>About</h1>
				<p>This is the about page.</p>
			</body>
			</html>
		`),
	}, nil
})

Resource Handler ​

Context ​

Input ​

Output ​

Send HTML response ​

Resource Handler

Context

Input

Output

Send HTML response