api查询语言 -- graphql

项目地址：
https://github.com/graphql-go/graphql

用法：

1. main.go：

    package main
    import (
        "encoding/json"
        "fmt"
        "github.com/graphql-go/graphql"
        "html/template"
        "math/rand"
        "net/http"
        "time"
    )
    type User struct {
        ID   int
        Name string
    }
    // 测试数据
    var UserList = []User{
        {
            1,
            "old user",
        },
    }
    var queryType = graphql.NewObject(graphql.ObjectConfig{
        Name:        "user",
        Description: "用户字段",
        Fields: graphql.Fields{
            "id": &graphql.Field{
                Type:        graphql.ID,
                Description: "ID",
            },
            "name": &graphql.Field{
                Type:        graphql.String,
                Description: "名字",
            },
        },
    })
    func main() {
        query := graphql.NewObject(graphql.ObjectConfig{
            Name:        graphql.DirectiveLocationQuery,
            Description: "读操作",
            Fields: graphql.Fields{
                "getUserList": &graphql.Field{
                    Type:        graphql.NewList(queryType),
                    Description: "获取用户列表",
                    Args: graphql.FieldConfigArgument{
                        "page": &graphql.ArgumentConfig{
                            Type:         graphql.Int,
                            DefaultValue: 1,
                        },
                        "query": &graphql.ArgumentConfig{
                            Type: graphql.String,
                        },
                    },
                    Resolve: func(params graphql.ResolveParams) (interface{}, error) {
                        fmt.Printf("args: %v \n", params.Args)
                        return UserList, nil
                    },
                },
            }})
        mutation := graphql.NewObject(graphql.ObjectConfig{
            Name:        graphql.DirectiveLocationMutation,
            Description: "写操作",
            Fields: graphql.Fields{
                "createUser": &graphql.Field{
                    Type:        queryType,
                    Description: "创建用户",
                    Args: graphql.FieldConfigArgument{
                        "name": &graphql.ArgumentConfig{
                            Type: graphql.String,
                        },
                    },
                    Resolve: func(params graphql.ResolveParams) (interface{}, error) {
                        name := params.Args["name"]
                        rand.Seed(time.Now().UnixNano())
                        id := rand.Intn(10000)
                        user := User{
                            ID:   id,
                            Name: name.(string),
                        }
                        UserList = append(UserList, user)
                        return UserList[len(UserList)-1], nil
                    },
                },
            },
        })
        schema, err := graphql.NewSchema(graphql.SchemaConfig{
            Query:    query,
            Mutation: mutation,
        })
        if err != nil {
            panic("创建 schema 失败：" + err.Error())
        }
        http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
            w.Header().Add("Content-Type", "text/html; charset=utf-8")
            w.WriteHeader(http.StatusOK)
            t, err := template.ParseFiles("index.html")
            if err != nil {
                fmt.Println("模板解析失败：" + err.Error())
                return
            }
            if err := t.Execute(w, nil); err != nil {
                fmt.Println("模板执行失败：" + err.Error())
            }
        })
        http.HandleFunc("/graphql", func(w http.ResponseWriter, r *http.Request) {
            if err := r.ParseForm(); err != nil {
                fmt.Println("参数解析失败：" + err.Error())
            }
            sql := r.Form["sql"]
            w.Header().Add("Content-Type", "application/json; charset=utf-8")
            w.WriteHeader(http.StatusOK)
            params := graphql.Params{Schema: schema, RequestString: sql[0]}
            res := graphql.Do(params)
            if len(res.Errors) > 0 {
                fmt.Println("请求失败：", res.Errors)
            }
            jsonByte, err := json.Marshal(res)
            if err != nil {
                fmt.Println("json编码失败：" + err.Error())
            }
            if _, err := fmt.Fprintln(w, string(jsonByte)); err != nil {
                fmt.Println("输出失败：" + err.Error())
            }
        })
        fmt.Println("访问地址：http://localhost:8080")
        if err := http.ListenAndServe("localhost:8080", nil); err != nil {
            fmt.Println("服务启动失败：" + err.Error())
        }
    }

2. index.html：

    <!doctype html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport"
              content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
        <meta http-equiv="X-UA-Compatible" content="ie=edge">
        <title>graphql测试</title>
        <style>
            .title {
                font-size: 1.2rem;
            }
            textarea {
                width: 500px;
                height: 200px;
                resize: none;
            }
        </style>
        <script src="http://file.job520.net/other/jquery/jquery-1.12.4.min.js"></script>
    </head>
    <body>
    <div>
        <label for="input" class="title">input:</label>
    </div>
    <textarea id="input"></textarea>
    <div>
        <button id="requestRead">读请求</button>
        <button id="requestWrite">写请求</button>
    </div>
    <div>
        <label for="output" class="title">output:</label>
    </div>
    <textarea id="output" disabled></textarea>
    <script>
        var read = "query{\n  getUserList(query:\"old user\"){\n    id\n    name\n  }\n}"
        var write = "mutation{\n  createUser(name:\"new user\"){\n    id\n    name\n  }\n}"
        function sendRequest() {
            $.post(
                "http://localhost:8080/graphql",
                {
                    sql: $("#input").val()
                },
                function (res) {
                    var str = JSON.stringify(res)
                    $("#output").val(str)
                }
            )
        }
        $("#requestRead").click(function () {
            $("#input").val(read)
            sendRequest()
        })
        $("#requestWrite").click(function () {
            $("#input").val(write)
            sendRequest()
        })
    </script>
    </body>
    </html>