Cosmos-- 三.教程 -- 11.nameservice模

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第三章教程:

1. 开始
2. 程序目标
3. 开始编写你的程序
4. Keeper
5. Msg和Handler
6. SetName
7. BuyName
8. Querier
9. Codec文件
10. Nameservice模块的CLI
11. nameservice模块的REST接口
12. 引入你的模块并完成程序
13. Entrypoint
14. 编译你的程序
15. 编译并运行程序
16. 运行REST路由

nameservice模块的REST接口

你的模块还可以公开REST接口，以允许对模块功能的可编程访问。首先创建一个文件来保存HTTP的handler：

• ./x/nameservice/client/rest/rest.go

引入模块和定义常量：

你的应用程序需要导入你刚编写的代码。这里导入路径设置为此存储库（github.com/cosmos/sdk-application-tutorial/x/nameservice）。如果您是在自己的仓库中进行的前面的操作，则需要更改导入路径（github.com/{.Username}/{.Project.Repo}/x/nameservice）。

package rest

import (
    "fmt"
    "net/http"

    "github.com/cosmos/cosmos-sdk/client/context"
    "github.com/cosmos/cosmos-sdk/client/rest"
    "github.com/cosmos/cosmos-sdk/codec"
    sdk "github.com/cosmos/cosmos-sdk/types"
    "github.com/cosmos/sdk-application-tutorial/x/nameservice"

    "github.com/gorilla/mux"
)

const (
    restName = "name"
)

RegisterRoutes

首先在RegisterRoutes函数中为模块定义REST客户端接口。路由都以模块名称开头，以防止命名空间与其他模块的路径冲突：

// RegisterRoutes - Central function to define routes that get registered by the main application
func RegisterRoutes(cliCtx context.CLIContext, r *mux.Router, cdc *codec.Codec, storeName string) {
    r.HandleFunc(fmt.Sprintf("/%s/names", storeName), buyNameHandler(cdc, cliCtx)).Methods("POST")
    r.HandleFunc(fmt.Sprintf("/%s/names", storeName), setNameHandler(cdc, cliCtx)).Methods("PUT")
    r.HandleFunc(fmt.Sprintf("/%s/names/{%s}", storeName, restName), resolveNameHandler(cdc, cliCtx, storeName)).Methods("GET")
    r.HandleFunc(fmt.Sprintf("/%s/names/{%s}/whois", storeName, restName), whoIsHandler(cdc, cliCtx, storeName)).Methods("GET")
}

Query Handlers

接下来，是时候定义上面提到的处理程序了。这些与前面定义的CLI方法非常相似。首先开始whois和resolve查询：

func resolveNameHandler(cdc *codec.Codec, cliCtx context.CLIContext, storeName string) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        vars := mux.Vars(r)
        paramType := vars[restName]

        res, err := cliCtx.QueryWithData(fmt.Sprintf("custom/%s/resolve/%s", storeName, paramType), nil)
        if err != nil {
            rest.WriteErrorResponse(w, http.StatusNotFound, err.Error())
            return
        }

        rest.PostProcessResponse(w, cdc, res, cliCtx.Indent)
    }
}

func whoIsHandler(cdc *codec.Codec, cliCtx context.CLIContext, storeName string) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        vars := mux.Vars(r)
        paramType := vars[restName]

        res, err := cliCtx.QueryWithData(fmt.Sprintf("custom/%s/whois/%s", storeName, paramType), nil)
        if err != nil {
            rest.WriteErrorResponse(w, http.StatusNotFound, err.Error())
            return
        }

        rest.PostProcessResponse(w, cdc, res, cliCtx.Indent)
    }
}

上述代码要注意：

• 请注意，我们使用相同的cliCtx.QueryWithData函数来获取数据
• 这些函数与相应的CLI功能几乎相同

Tx Handlers

现在定义buyName和setName交易路径：

type buyNameReq struct {
    BaseReq rest.BaseReq `json:"base_req"`
    Name    string       `json:"name"`
    Amount  string       `json:"amount"`
    Buyer   string       `json:"buyer"`
}

func buyNameHandler(cdc *codec.Codec, cliCtx context.CLIContext) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        var req buyNameReq

        if !rest.ReadRESTReq(w, r, cdc, &req) {
            rest.WriteErrorResponse(w, http.StatusBadRequest, "failed to parse request")
            return
        }

        baseReq := req.BaseReq.Sanitize()
        if !baseReq.ValidateBasic(w) {
            return
        }

        addr, err := sdk.AccAddressFromBech32(req.Buyer)
        if err != nil {
            rest.WriteErrorResponse(w, http.StatusBadRequest, err.Error())
            return
        }

        coins, err := sdk.ParseCoins(req.Amount)
        if err != nil {
            rest.WriteErrorResponse(w, http.StatusBadRequest, err.Error())
            return
        }

        // create the message
        msg := nameservice.NewMsgBuyName(req.Name, coins, addr)
        err = msg.ValidateBasic()
        if err != nil {
            rest.WriteErrorResponse(w, http.StatusBadRequest, err.Error())
            return
        }

        rest.CompleteAndBroadcastTxREST(w, r, cliCtx, baseReq, []sdk.Msg{msg}, cdc)
    }
}

type setNameReq struct {
    BaseReq rest.BaseReq `json:"base_req"`
    Name    string       `json:"name"`
    Value   string       `json:"value"`
    Owner   string       `json:"owner"`
}

func setNameHandler(cdc *codec.Codec, cliCtx context.CLIContext) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        var req setNameReq
        if !rest.ReadRESTReq(w, r, cdc, &req) {
            rest.WriteErrorResponse(w, http.StatusBadRequest, "failed to parse request")
            return
        }

        baseReq := req.BaseReq.Sanitize()
        if !baseReq.ValidateBasic(w) {
            return
        }

        addr, err := sdk.AccAddressFromBech32(req.Owner)
        if err != nil {
            rest.WriteErrorResponse(w, http.StatusBadRequest, err.Error())
            return
        }

        // create the message
        msg := nameservice.NewMsgSetName(req.Name, req.Value, addr)
        err = msg.ValidateBasic()
        if err != nil {
            rest.WriteErrorResponse(w, http.StatusBadRequest, err.Error())
            return
        }

        rest.CompleteAndBroadcastTxREST(w, r, cliCtx, baseReq, []sdk.Msg{msg}, cdc)
    }
}

注意上述代码：

• BaseReq包含用于进行交易的基本必填字段（使用哪个密钥，如何解码，使用哪条链等等）并且如所示被设计成嵌入形式。

• baseReq.ValidateBasic和utils.CompleteAndBroadcastTxREST为你设置响应代码，因此你需担心在使用这些函数时处理错误或成功。