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|
# fn
This library aims to simplify the construction of JSON API service,
`fn.Wrap` is able to wrap any function to adapt the interface of
`http.Handler`, which unmarshals POST data to a struct automatically.
## Benchmark
```
BenchmarkIsBuiltinType-8 50000000 33.5 ns/op 0 B/op 0 allocs/op
BenchmarkSimplePlainAdapter_Invoke-8 2000000 757 ns/op 195 B/op 3 allocs/op
BenchmarkSimpleUnaryAdapter_Invoke-8 2000000 681 ns/op 946 B/op 5 allocs/op
BenchmarkGenericAdapter_Invoke-8 2000000 708 ns/op 946 B/op 5 allocs/op
```
## Support types
```
io.ReadCloser // request.Body
http.Header // request.Header
fn.Form // request.Form
fn.PostForm // request.PostForm
*fn.Form // request.Form
*fn.PostForm // request.PostForm
*url.URL // request.URL
*multipart.Form // request.MultipartForm
*http.Request // raw request
```
## Usage
```go
http.Handle("/test", fn.Wrap(test))
func test(io.ReadCloser, http.Header, fn.Form, fn.PostForm, *CustomizedRequestType, *url.URL, *multipart.Form) (*CustomizedResponseType, error)
```
## Examples
### Basic
```go
package examples
import (
"io"
"mime/multipart"
"net/http"
"net/url"
"github.com/pingcap/fn"
)
type Request struct {
Username string `json:"username"`
Password string `json:"password"`
}
type Response struct {
Token string `json:"token"`
}
func api1() (*Response, error) {
return &Response{Token: "token"}, nil
}
func api2(request *Request) (*Response, error) {
token := request.Username + request.Password
return &Response{Token: token}, nil
}
func api3(rawreq *http.Request, request *Request) (*Response, error) {
token := request.Username + request.Password
return &Response{Token: token}, nil
}
func api4(rawreq http.Header, request *Request) (*Response, error) {
token := request.Username + request.Password
return &Response{Token: token}, nil
}
func api5(form *fn.Form, request *Request) (*Response, error) {
token := request.Username + request.Password + form.Get("type")
return &Response{Token: token}, nil
}
func api6(body io.ReadCloser, request *Request) (*Response, error) {
token := request.Username + request.Password
return &Response{Token: token}, nil
}
func api7(form *multipart.Form, request *Request) (*Response, error) {
token := request.Username + request.Password
return &Response{Token: token}, nil
}
func api7(urls *url.URL, request *Request) (*Response, error) {
token := request.Username + request.Password
return &Response{Token: token}, nil
}
func api8(urls *url.URL, form *multipart.Form, body io.ReadCloser, rawreq http.Header, request *Request) (*Response, error) {
token := request.Username + request.Password
return &Response{Token: token}, nil
}
```
### Plugins
```go
package examples
import (
"context"
"errors"
"io"
"log"
"mime/multipart"
"net/http"
"net/url"
"strings"
"github.com/pingcap/fn"
)
var PermissionDenied = errors.New("permission denied")
func logger(ctx context.Context, req *http.Request) (context.Context, error) {
log.Println("Request", req.RemoteAddr, req.URL.String())
return ctx, nil
}
func ipWhitelist(ctx context.Context, req *http.Request) (context.Context, error) {
if strings.HasPrefix(req.RemoteAddr, "172.168") {
return ctx, PermissionDenied
}
return ctx, nil
}
func auth(ctx context.Context, req *http.Request) (context.Context, error) {
token := req.Header.Get("X-Auth-token")
_ = token // Validate token (e.g: query db)
if token != "valid" {
return ctx, fn.ErrorWithStatusCode(PermissionDenied, http.StatusForbidden)
}
return ctx, nil
}
type Request struct {
Username string `json:"username"`
Password string `json:"password"`
}
type Response struct {
Token string `json:"token"`
}
func example() {
fn.Plugin(logger, ipWhitelist, auth)
http.Handle("/api1", fn.Wrap(api1))
http.Handle("/api2", fn.Wrap(api2))
}
// api1 and api2 request have be validated by `ipWhitelist` and `auth`
func api1() (*Response, error) {
return &Response{Token: "token"}, nil
}
func api2(request *Request) (*Response, error) {
token := request.Username + request.Password
return &Response{Token: token}, nil
}
```
### `fn.Group`
```go
package examples
import (
"context"
"errors"
"io"
"log"
"mime/multipart"
"net/http"
"net/url"
"strings"
"github.com/pingcap/fn"
)
var PermissionDenied = errors.New("permission denied")
func logger(ctx context.Context, req *http.Request) (context.Context, error) {
log.Println("Request", req.RemoteAddr, req.URL.String())
return ctx, nil
}
func ipWhitelist(ctx context.Context, req *http.Request) (context.Context, error) {
if strings.HasPrefix(req.RemoteAddr, "172.168") {
return ctx, PermissionDenied
}
return ctx, nil
}
func auth(ctx context.Context, req *http.Request) (context.Context, error) {
token := req.Header.Get("X-Auth-token")
_ = token // Validate token (e.g: query db)
if token != "valid" {
return ctx, fn.ErrorWithStatusCode(PermissionDenied, http.StatusForbidden)
}
return ctx, nil
}
type User struct {
Balance int64
}
func queryUserFromRedis(ctx context.Context, req *http.Request) (context.Context, error) {
token := req.Header.Get("X-Auth-token")
_ = token // Validate token (e.g: query db)
if token != "valid" {
return ctx, fn.ErrorWithStatusCode(PermissionDenied, http.StatusForbidden)
}
user := &User{
Balance: 10000, // balance from redis
}
return context.WithValue(ctx, "user", user), nil
}
type Response struct {
Balance int64 `json:"balance"`
}
func example() {
// Global plugins
fn.Plugin(logger, ipWhitelist, auth)
group := fn.NewGroup()
// Group plugins
group.Plugin(queryUserFromRedis)
http.Handle("/user/balance", group.Wrap(fetchBalance))
http.Handle("/user/buy", group.Wrap(buy))
}
func fetchBalance(ctx context.Context) (*Response, error) {
user := ctx.Value("user").(*User)
return &Response{Balance: user.Balance}, nil
}
func buy(ctx context.Context) (*Response, error) {
user := ctx.Value("user").(*User)
if user.Balance < 100 {
return nil, errors.New("please check balance")
}
user.Balance -= 100
return &Response{Balance: user.Balance}, nil
}
```
### ResponseEncoder
```go
package examples
import (
"context"
"errors"
"io"
"log"
"mime/multipart"
"net/http"
"net/url"
"strings"
"github.com/pingcap/fn"
)
var PermissionDenied = errors.New("permission denied")
func logger(ctx context.Context, req *http.Request) (context.Context, error) {
log.Println("Request", req.RemoteAddr, req.URL.String())
return ctx, nil
}
func ipWhitelist(ctx context.Context, req *http.Request) (context.Context, error) {
if strings.HasPrefix(req.RemoteAddr, "172.168") {
return ctx, PermissionDenied
}
return ctx, nil
}
func auth(ctx context.Context, req *http.Request) (context.Context, error) {
token := req.Header.Get("X-Auth-token")
_ = token // Validate token (e.g: query db)
if token != "valid" {
return ctx, fn.ErrorWithStatusCode(PermissionDenied, http.StatusForbidden)
}
return ctx, nil
}
func injectRequest(ctx context.Context, req *http.Request) (context.Context, error) {
return context.WithValue(ctx, "_rawreq", req), nil
}
type User struct {
Balance int64
}
func queryUserFromRedis(ctx context.Context, req *http.Request) (context.Context, error) {
token := req.Header.Get("X-Auth-token")
_ = token // Validate token (e.g: query db)
if token != "valid" {
return ctx, fn.ErrorWithStatusCode(PermissionDenied, http.StatusForbidden)
}
user := &User{
Balance: 10000, // balance from redis
}
return context.WithValue(ctx, "user", user), nil
}
type Response struct {
Balance int64 `json:"balance"`
}
type ResponseMessage struct {
Code int `json:"code"`
Data interface{} `json:"data"`
}
type ErrorMessage struct {
Code int `json:"code"`
Error string `json:"error"`
}
func example() {
// Global plugins
fn.Plugin(logger, ipWhitelist, auth, injectRequest)
// Uniform all responses
fn.SetErrorEncoder(func(ctx context.Context, err error) interface{} {
req := ctx.Value("_rawreq").(*http.Request)
log.Println("Error occurred: ", req.URL, err)
return &ErrorMessage{
Code: -1,
Error: err.Error(),
}
})
fn.SetResponseEncoder(func(ctx context.Context, payload interface{}) interface{} {
return &ResponseMessage{
Code: 1,
Data: payload,
}
})
group := fn.NewGroup()
// Group plugins
group.Plugin(queryUserFromRedis)
http.Handle("/user/balance", group.Wrap(fetchBalance))
http.Handle("/user/buy", group.Wrap(buy))
}
func fetchBalance(ctx context.Context) (*Response, error) {
user := ctx.Value("user").(*User)
return &Response{Balance: user.Balance}, nil
}
func buy(ctx context.Context) (*Response, error) {
user := ctx.Value("user").(*User)
if user.Balance < 100 {
return nil, errors.New("please check balance")
}
user.Balance -= 100
return &Response{Balance: user.Balance}, nil
}
```
|
