forked from looplab/eventhorizon
/
command.go
63 lines (55 loc) · 2.06 KB
/
command.go
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// Copyright (c) 2017 - Max Ekman <max@looplab.se>
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package httputils
import (
"context"
"encoding/json"
"io/ioutil"
"net/http"
eh "github.com/looplab/eventhorizon"
)
// CommandHandler is a HTTP handler for eventhorizon.Commands. Commands must be
// registered with eventhorizon.RegisterCommand(). It expects a POST with a JSON
// body that will be unmarshalled into the command.
func CommandHandler(commandHandler eh.CommandHandler, commandType eh.CommandType) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.Method != "POST" {
http.Error(w, "unsuported method: "+r.Method, http.StatusMethodNotAllowed)
return
}
cmd, err := eh.CreateCommand(commandType)
if err != nil {
http.Error(w, "could not create command: "+err.Error(), http.StatusBadRequest)
return
}
b, err := ioutil.ReadAll(r.Body)
if err != nil {
http.Error(w, "could not read command: "+err.Error(), http.StatusBadRequest)
return
}
if err := json.Unmarshal(b, &cmd); err != nil {
http.Error(w, "could not decode command: "+err.Error(), http.StatusBadRequest)
return
}
// NOTE: Use a new context when handling, else it will be cancelled with
// the HTTP request which will cause projectors etc to fail if they run
// async in goroutines past the request.
ctx := context.Background()
if err := commandHandler.HandleCommand(ctx, cmd); err != nil {
http.Error(w, "could not handle command: "+err.Error(), http.StatusBadRequest)
return
}
w.WriteHeader(http.StatusOK)
})
}