# 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:
Source: https://fastschema.com/docs/framework/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.
```go
type Context interface {
context.Context
TraceID() string
User() *User
Local(string, ...any) (val any)
Logger() logger.Logger
Bind(any) error
SetArg(string, string) string
Args() map[string]string
Arg(name string, defaults ...string) string
ArgInt(name string, defaults ...int) int
Body() ([]byte, error)
Payload() (*entity.Entity, error)
Resource() *Resource
AuthToken() string
Next() error
Result(...*Result) *Result
Files() ([]*File, error)
Redirect(string) error
WSClient() WSClient
IP() string
}
```
## 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)`
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
```go
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(`
About
About
This is the about page.
`),
}, nil
})
```