feat: add support for core-command read

This commit adds support for the `read` command of the `command` endpoint.

```
edgex-cli command read
```

Adds support for the `-j`, `-v` flags, which generate raw JSON output.
Adds support for the `-p` flag; if set, a successful GET will result in
an event being pushed to the EdgeX system
Adds support for the `-r` flag; if set, there will be no Event returned
in the http response

Signed-off-by: Mengyi <mengyi.wang@canonical.com>

internal/cmd/command.go

@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2021 Canonical Ltd
+ *
+ *  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.
+ *
+ * SPDX-License-Identifier: Apache-2.0'
+ */
+
+package cmd
+
+import (
+	jsonpkg "encoding/json"
+	"fmt"
+	"github.com/spf13/cobra"
+	"os"
+	"text/tabwriter"
+)
+
+var deviceName, commandName string
+var pushEvent, noReturnEvent bool
+
+func init() {
+	commandCmd := initCommandCommand()
+	initReadCommand(commandCmd)
+}
+
+func initCommandCommand() *cobra.Command {
+	var cmd = &cobra.Command{
+		Use:          "command",
+		Short:        "read, write and list commands",
+		Long:         ``,
+		SilenceUsage: true,
+	}
+	rootCmd.AddCommand(cmd)
+	addFormatFlags(cmd)
+	return cmd
+}
+
+func initReadCommand(cmd *cobra.Command) {
+	var readCmd = &cobra.Command{
+		Use:          "read",
+		Short:        "read command referenced by the command name and device name",
+		Long:         `Issue the specified read command referenced by the command name to the device/sensor that is also referenced by name`,
+		RunE:         handleReadCommand,
+		SilenceUsage: true,
+	}
+	readCmd.Flags().StringVarP(&deviceName, "device", "d", "", "Specify the name of device")
+	readCmd.Flags().StringVarP(&commandName, "command", "c", "", "Specify the name of the command to be executed")
+	readCmd.Flags().BoolVarP(&pushEvent, "pushevent", "p", false, "If set, a successful GET will result in an event being pushed to the EdgeX system")
+	readCmd.Flags().BoolVarP(&noReturnEvent, "noreturnevent", "r", false, "If set, there will be no Event returned in the http response")
+	readCmd.MarkFlagRequired("device")
+	readCmd.MarkFlagRequired("command")
+	cmd.AddCommand(readCmd)
+	addFormatFlags(readCmd)
+}
+
+func handleReadCommand(cmd *cobra.Command, args []string) error {
+	dsPushEvent := boolToString(pushEvent)
+	dsReturnEvent := boolToString(!noReturnEvent)
+
+	//issue READ command and handle output if nothing can be displayed
+	response, err := getCoreCommandService().IssueReadCommand(deviceName, commandName, dsPushEvent, dsReturnEvent)
+	if err != nil {
+		return err
+	}
+
+	if response == nil {
+		fmt.Println("Read command issued. Nothing to display. Please retry without flag -r.")
+		return nil
+	}
+
+	//print READ command's output with one of these formats: JSON, verbose or table
+	if json || verbose {
+		stringifiedResponse, err := jsonpkg.Marshal(response)
+		if err != nil {
+			return err
+		}
+
+		if verbose {
+			url := getCoreCommandService().GetReadEndpoint(deviceName, commandName, dsPushEvent, dsReturnEvent)
+			fmt.Printf("Result:%s\nURL: %s\n", string(stringifiedResponse), url)
+		} else {
+			fmt.Printf("%s\n", stringifiedResponse)
+		}
+	} else {
+		w := tabwriter.NewWriter(os.Stdout, 1, 1, 2, ' ', 0)
+		fmt.Fprintln(w, "Command Name\tDevice Name\tProfile Name\tValue Type\tValue")
+		for _, reading := range response.Event.Readings {
+			fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\n",
+				commandName, reading.DeviceName, reading.ProfileName, reading.ValueType, reading.Value)
+		}
+		w.Flush()
+	}
+	return nil
+}
+
+//using by READ when it specified dsPushEvent or dsReturnEvent
+func boolToString(b bool) string {
+	if b {
+		return "yes"
+	} else {
+		return "no"
+	}
+}

internal/cmd/common.go

@@ -41,6 +41,10 @@ func getSelectedServiceKey() string {
 	}
 }
 
+func getCoreCommandService() service.Service {
+	return config.GetCoreService(common.CoreCommandServiceKey)
+}
+
 func getSelectedServices() map[string]service.Service {
 	key := getSelectedServiceKey()
 	if key == "" {
@@ -56,13 +60,13 @@ func getSelectedServices() map[string]service.Service {
 
 func addFormatFlags(cmd *cobra.Command) {
 	cmd.Flags().BoolVarP(&json, "json", "j", false, "show the raw JSON response")
-	cmd.Flags().BoolVarP(&verbose, "debug", "d", false, "show verbose/debug output")
+	cmd.Flags().BoolVarP(&verbose, "verbose", "v", false, "show verbose/debug output")
 
 }
 
 func addStandardFlags(cmd *cobra.Command) {
 	addFormatFlags(cmd)
-	cmd.Flags().BoolVarP(&data, "data", "", false, "use core-data service endpoint")
+	cmd.Flags().BoolVarP(&data, "data", "d", false, "use core-data service endpoint")
 	cmd.Flags().BoolVarP(&command, "command", "c", false, "use core-command service endpoint")
 	cmd.Flags().BoolVarP(&metadata, "metadata", "m", false, "use core-metadata service endpoint")
 	cmd.Flags().BoolVarP(&scheduler, "scheduler", "s", false, "use support-scheduler service endpoint")

internal/service/corecommandservice.go

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2021 Canonical Ltd
+ *
+ *  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.
+ *
+ * SPDX-License-Identifier: Apache-2.0'
+ */
+
+package service
+
+import (
+	"context"
+	"fmt"
+	"github.com/edgexfoundry/go-mod-core-contracts/v2/clients/http"
+	"github.com/edgexfoundry/go-mod-core-contracts/v2/clients/interfaces"
+	"github.com/edgexfoundry/go-mod-core-contracts/v2/common"
+	"github.com/edgexfoundry/go-mod-core-contracts/v2/dtos/responses"
+	"strings"
+)
+
+func (c Service) IssueReadCommand(deviceName string, commandName string, dsPushEvent string, dsReturnEvent string) (response *responses.EventResponse, err error) {
+	client := c.getCommandClient()
+	response, err = client.IssueGetCommandByName(context.Background(), deviceName, commandName, dsPushEvent, dsReturnEvent)
+	return
+}
+
+func (c Service) GetReadEndpoint(deviceName string, commandName string, dsPushEvent string, dsReturnEvent string) string {
+	url := c.getEndpointUrl(common.ApiDeviceNameCommandNameRoute)
+	replacer := strings.NewReplacer("{name}", deviceName, "{command}", commandName)
+	return replacer.Replace(url) + "?ds-pushevent=" + dsPushEvent + "&ds-returnevent=" + dsReturnEvent
+}
+
+func (c Service) getEndpointUrl(endpoint string) string {
+	return fmt.Sprintf("http://%s:%v%s", c.Host, c.Port, endpoint)
+}
+
+func (c Service) getCommandClient() interfaces.CommandClient {
+	url := fmt.Sprintf("http://%s:%v", c.Host, c.Port)
+	return http.NewCommandClient(url)
+}