api2

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 Go to latest Published: Dec 6, 2020 License: MIT Imports: 24 Imported by: 0

README

api2

godoc

Go library to make HTTP API clients and servers.

Package api2 provides types and functions used to define interfaces of client-server API and facilitate creation of server and client for it. You define a common structure (GetRoutes, see below) in Go and api2 makes both HTTP client and HTTP server for you. You do not have to do JSON encoding-decoding yourself and to duplicate schema information (data types and path) in client.

How to use this package.

Organize your code in services. Each service provides some domain specific functionality. It is a Go type whose methods correspond to exposed RPC's of the API. Each method has the following signature:

func(ctx, *Request) (*Response, error)

Let's define a service Foo with method Bar.

type Foo struct {
	...
}

type BarRequest struct {
	// These fields are stored in JSON format in body.
	Name string `json:"name"`

	// These fields are GET parameters.
	UserID int `query:"user_id"`

	// These fields are headers.
	FileHash string `header:"file_hash"`

	// These fields are skipped.
	SkippedField int `json:"-"`
}

type BarResponse struct {
	// These fields are stored in JSON format in body.
	FileSize int `json:"file_size"`

	// These fields are headers.
	FileHash string `header:"file_hash"`

	// These fields are skipped.
	SkippedField int `json:"-"`
}

func (s *Foo) Bar(ctx context.Context, req *BarRequest) (*BarResponse, error) {
	...
}

A field must not have more than one of tags: json, query, header. Fields in query and header parts are encoded and decoded with fmt.Sprintf and fmt.Sscanf. Strings are not decoded with fmt.Sscanf, but passed as is. Types implementing encoding.TextMarshaler and encoding.TextUnmarshaler are encoded and decoded using it. If no field is no JSON field in the struct, then HTTP body is skipped.

Now let's write the function that generates the table of routes:

func GetRoutes(s *Foo) []api2.Route {
	return []api2.Route{
		{
			Method:    http.MethodPost,
			Path:      "/v1/foo/bar",
			Handler:   s.Bar,
			Transport: &api2.JsonTransport{},
		},
	}
}

You can add multiple routes with the same path, but in this case their HTTP methods must be different so that they can be distinguished.

If Transport is not set, DefaultTransport is used which is defined as &api2.JsonTransport{}.

In the server you need a real instance of service Foo to pass to GetRoutes. Then just bind the routes to http.ServeMux and run the server:

// Server.
foo := NewFoo(...)
routes := GetRoutes(foo)
api2.BindRoutes(http.DefaultServeMux, routes)
log.Fatal(http.ListenAndServe(":8080", nil))

The server is running. It serves foo.Bar function on path /v1/foo/bar with HTTP method Post.

Now let's create the client:

// Client.
routes := GetRoutes(nil)
client := api2.NewClient(routes, "http://127.0.0.1:8080")
barRes := &BarResponse{}
err := client.Call(context.Background(), barRes, &BarRequest{
	...
})
if err != nil {
	panic(err)
}
// Server's response is in variable barRes.

Note that you don't have to pass a real service object to GetRoutes on client side. You can pass nil, it is sufficient to pass all needed information about request and response types in the routes table, that is used by client to find a proper route.

You can make GetRoutes accepting an interface instead of a concrete Service type. In this case you can not get method handlers by s.Bar, because this code panics if s is nil interface. As a workaround api2 provides function Method(service pointer, methodName) which you can use:

type Service interface {
	Bar(ctx context.Context, req *BarRequest) (*BarResponse, error)
}

func GetRoutes(s Service) []api2.Route {
	return []api2.Route{
		{Method: http.MethodPost, Path: "/v1/foo/bar", Handler: api2.Method(&s, "Bar"), Transport: &api2.JsonTransport{}},
	}
}

If you have function GetRoutes in package foo as above you can generate static client for it in file client.go located near the file in which GetRoutes is defined:

api2.GenerateClient(foo.GetRoutes)

You can find an example in directory example. To build and run it:

$ go get github.com/starius/api2/example/...
$ server &
$ client
test

Code generation code is located in directory example/gen. To regenerate file client.go run:

$ go generate github.com/starius/api2/example

Documentation

Overview

Package api2 provides types and functions used to define interfaces of client-server API and facilitate creation of server and client for it.

How to use this package. Organize your code in services. Each service provides some domain specific functionality. It is a Go type whose methods correspond to exposed RPC's of the API. Each method has the following signature: 

func(ctx, *Request) (*Response, error)

Let's define a service Foo with method Bar. 

type Foo struct {
	...
}

type BarRequest struct {
	// These fields are stored in JSON format in body.
	Name string `json:"name"`

	// These fields are GET parameters.
	UserID int `query:"user_id"`

	// These fields are headers.
	FileHash string `header:"file_hash"`

	// These fields are skipped.
	SkippedField int `json:"-"`
}

type BarResponse struct {
	// These fields are stored in JSON format in body.
	FileSize int `json:"file_size"`

	// These fields are headers.
	FileHash string `header:"file_hash"`

	// These fields are skipped.
	SkippedField int `json:"-"`
}

func (s *Foo) Bar(ctx context.Context, req *BarRequest) (*BarResponse, error) {
	...
}

A field must not have more than one of tags: json, query, header. Fields in query and header parts are encoded and decoded with fmt.Sprintf and fmt.Sscanf. Strings are not decoded with fmt.Sscanf, but passed as is. Types implementing encoding.TextMarshaler and encoding.TextUnmarshaler are encoded and decoded using it. If no field is no JSON field in the struct, then HTTP body is skipped.

Now let's write the function that generates the table of routes: 

func GetRoutes(s *Foo) []api2.Route {
	return []api2.Route{
		{
			Method:    http.MethodPost,
			Path:      "/v1/foo/bar",
			Handler:   s.Bar,
			Transport: &api2.JsonTransport{},
		},
	}
}

You can add multiple routes with the same path, but in this case their HTTP methods must be different so that they can be distinguished.

If Transport is not set, DefaultTransport is used which is defined as &api2.JsonTransport{}.

In the server you need a real instance of service Foo to pass to GetRoutes. Then just bind the routes to http.ServeMux and run the server: 

// Server.
foo := NewFoo(...)
routes := GetRoutes(foo)
api2.BindRoutes(http.DefaultServeMux, routes)
log.Fatal(http.ListenAndServe(":8080", nil))

The server is running. It serves foo.Bar function on path /v1/foo/bar with HTTP method Post.

Now let's create the client: 

// Client.
routes := GetRoutes(nil)
client := api2.NewClient(routes, "http://127.0.0.1:8080")
barRes := &BarResponse{}
err := client.Call(context.Background(), barRes, &BarRequest{
	...
})
if err != nil {
	panic(err)
}
// Server's response is in variable barRes.

Note that you don't have to pass a real service object to GetRoutes on client side. You can pass nil, it is sufficient to pass all needed information about request and response types in the routes table, that is used by client to find a proper route.

You can make GetRoutes accepting an interface instead of a concrete Service type. In this case you can not get method handlers by s.Bar, because this code panics if s is nil interface. As a workaround api2 provides function Method(service pointer, methodName) which you can use: 

type Service interface {
	Bar(ctx context.Context, req *BarRequest) (*BarResponse, error)
}

func GetRoutes(s Service) []api2.Route {
	return []api2.Route{
		{Method: http.MethodPost, Path: "/v1/foo/bar", Handler: api2.Method(&s, "Bar"), Transport: &api2.JsonTransport{}},
	}
}

If you have function GetRoutes in package foo as above you can generate static client for it in file client.go located near the file in which GetRoutes is defined: 

api2.GenerateClient(foo.GetRoutes)

Index

Constants

This section is empty.

Variables

View Source 
var DefaultTransport = &JsonTransport{}

Functions

func BindRoutes 

func BindRoutes(mux *http.ServeMux, routes []Route, opts ...Option)

BindRoutes adds handlers of routes to http.ServeMux.

func CustomParse 

func CustomParse(t reflect.Type) (typegen.IType, bool)

func GenerateClient 

func GenerateClient(getRoutes interface{})

GenerateClient generates file client.go with static client near the file in which passed GetRoutes function is defined.

func GenerateClientCode 

func GenerateClientCode(getRoutes interface{}) (code, clientFile string, err error)

GenerateClientCode accepts global function GetRoutes of a package and returns the code of static client and path to the file where the code should be saved (client.go in the same directory where GetRoutes and types of requests, responses and service are defined.

func GenerateTSClient 

func GenerateTSClient(options *TsGenConfig)

func Method 

func Method(servicePtr interface{}, methodName string) interface{}

func SerializeCustom 

func SerializeCustom(t reflect.Type) string

Types

type Client 

type Client struct {
	// contains filtered or unexported fields
}

Client is used on client-side to call remote methods provided by the API.

func NewClient 

func NewClient(routes []Route, baseURL string, opts ...Option) *Client

NewClient creates new instance of client.

The list of routes must provide all routes that this client is aware of. Paths from the table of routes are appended to baseURL to generate final URL used by HTTP client. All pairs of (request type, response type) must be unique in the table of routes.

func (*Client) Call 

func (c *Client) Call(ctx context.Context, response, request interface{}) error

Call calls remote method deduced by request and response types. Both request and response must be pointers to structs. The method must be called on exactly the same types as the corresponding method of a service.

type Config 

type Config struct {
	// contains filtered or unexported fields
}

func NewDefaultConfig 

func NewDefaultConfig() *Config

type FnInfo 

type FnInfo struct {
	PkgFull    string
	PkgName    string
	StructName string
	Method     string
}

func GetFnInfo 

func GetFnInfo(i interface{}) FnInfo

type FuncInfoer 

type FuncInfoer interface {
	FuncInfo() (pkgFull, pkgName, structName, method string)
}

type HttpError 

type HttpError interface {
	HttpCode() int
}

type JsonTransport 

type JsonTransport struct {
	RequestDecoder  func(context.Context, *http.Request, interface{}) (context.Context, error)
	ResponseEncoder func(context.Context, http.ResponseWriter, interface{}) error
	ErrorEncoder    func(context.Context, http.ResponseWriter, error) error
	RequestEncoder  func(ctx context.Context, method, url string, req interface{}) (*http.Request, error)
	ResponseDecoder func(context.Context, *http.Response, interface{}) error
	ErrorDecoder    func(context.Context, *http.Response) error
}

JsonTransport implements interface Transport for JSON encoding of requests and responses.

It recognizes GET parameter "human". If it is set, JSON in the response is pretty formatted.

To redefine some methods, set corresponding fields in the struct: 

&JsonTransport{RequestDecoder: func ...

func (*JsonTransport) DecodeError 

func (h *JsonTransport) DecodeError(ctx context.Context, res *http.Response) error

func (*JsonTransport) DecodeRequest 

func (h *JsonTransport) DecodeRequest(ctx context.Context, r *http.Request, req interface{}) (context.Context, error)

func (*JsonTransport) DecodeResponse 

func (h *JsonTransport) DecodeResponse(ctx context.Context, res *http.Response, response interface{}) error

func (*JsonTransport) EncodeError 

func (h *JsonTransport) EncodeError(ctx context.Context, w http.ResponseWriter, err error) error

func (*JsonTransport) EncodeRequest 

func (h *JsonTransport) EncodeRequest(ctx context.Context, method, urlStr string, req interface{}) (*http.Request, error)

func (*JsonTransport) EncodeResponse 

func (h *JsonTransport) EncodeResponse(ctx context.Context, w http.ResponseWriter, res interface{}) error

type Option 

type Option func(*Config)

func ErrorLogger 

func ErrorLogger(logger func(format string, args ...interface{})) Option

type Route 

type Route struct {
	// HTTP method.
	Method string

	// HTTP path. The same path can be used multiple times with different methods.
	Path string

	// Handler is a function with the following signature:
	// func(ctx, *Request) (*Response, error)
	// Request and Response are custom structures, unique to this route.
	Handler interface{}

	// The transport used in this route. If Transport is not set, DefaultTransport
	// is used.
	Transport Transport
}

Route describes one endpoint in the API, associated with particular method of some service.

type Transport 

type Transport interface {
	// Called by server.
	DecodeRequest(ctx context.Context, r *http.Request, req interface{}) (context.Context, error)
	EncodeResponse(ctx context.Context, w http.ResponseWriter, res interface{}) error
	EncodeError(ctx context.Context, w http.ResponseWriter, err error) error

	// Called by client.
	EncodeRequest(ctx context.Context, method, url string, req interface{}) (*http.Request, error)
	DecodeResponse(ctx context.Context, httpRes *http.Response, res interface{}) error
	DecodeError(ctx context.Context, httpRes *http.Response) error
}

Transport converts back and forth between HTTP and Request, Response types.

type TsGenConfig 

type TsGenConfig struct {
	OutDir         string
	ClientTemplate *template.Template
	Routes         []interface{}
	Types          []interface{}
}

Source Files

View all Source files

Directories

Path Synopsis
app
client
gen
example
example/types
tests/types

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