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第三章教程:
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。
