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Merge pull request #13 from graugans/feature/templates
Add the possibility to filter the get command with the go text/template package
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
|
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@@ -4,10 +4,40 @@ Copyright © 2023 Christian Ege <[email protected]> | |
| package cmd | ||
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| import ( | ||
| "encoding/json" | ||
| "errors" | ||
| "fmt" | ||
| "os" | ||
| "text/template" | ||
|
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| "github.com/graugans/go-ovp8xx/v2/pkg/ovp8xx" | ||
| "github.com/spf13/cobra" | ||
| ) | ||
|
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| // toJSON converts the given object to a JSON string representation. | ||
| // If an error occurs during marshaling, an empty string is returned. | ||
| // This is taken from https://github.com/intel/tfortools | ||
| func toJSON(obj interface{}) string { | ||
| b, err := json.MarshalIndent(obj, "", "\t") | ||
| if err != nil { | ||
| return "" | ||
| } | ||
| return string(b) | ||
| } | ||
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| // prefix can be used to create a list separated by s and the very first | ||
| // element is not prefixed. | ||
| func prefix(s string) func() string { | ||
| i := -1 | ||
| return func() string { | ||
| i++ | ||
| if i == 0 { | ||
| return "" | ||
| } | ||
| return s | ||
| } | ||
| } | ||
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| func getCommand(cmd *cobra.Command, args []string) error { | ||
| var result ovp8xx.Config | ||
| var err error | ||
|
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@@ -23,6 +53,35 @@ func getCommand(cmd *cobra.Command, args []string) error { | |
| if result, err = o3r.Get(helper.jsonPointers()); err != nil { | ||
| return err | ||
| } | ||
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| if cmd.Flags().Changed("format") { | ||
| if helper.prettyPrint() { | ||
| return errors.New("you can't use --pretty and --format at the same time") | ||
| } | ||
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| format, err := cmd.Flags().GetString("format") | ||
| if err != nil { | ||
| return fmt.Errorf("unable to get the format string from the command line: %w", err) | ||
| } | ||
| var inputData interface{} | ||
| if err = json.Unmarshal([]byte(result.String()), &inputData); err != nil { | ||
| return fmt.Errorf("unable to unmarshal the JSON data from the 'get' call: %w", err) | ||
| } | ||
| templateFunctions := template.FuncMap{ | ||
| "toJSON": toJSON, | ||
| "prefix": prefix, | ||
| } | ||
| tmpl, err := template.New("output").Funcs(templateFunctions).Parse(format) | ||
| if err != nil { | ||
| return fmt.Errorf("unable to parse the template: %w", err) | ||
| } | ||
|
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| if err := tmpl.Execute(os.Stdout, inputData); err != nil { | ||
| return fmt.Errorf("unable to execute the template: %w", err) | ||
| } | ||
| return nil | ||
| } | ||
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| if err := helper.printJSONResult(result.String()); err != nil { | ||
| return err | ||
| } | ||
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@@ -66,4 +125,5 @@ func init() { | |
| rootCmd.AddCommand(getCmd) | ||
| getCmd.Flags().StringSliceP("pointer", "p", []string{""}, "A JSON pointer to be queried") | ||
| getCmd.Flags().Bool("pretty", false, "Pretty print the JSON received from the device") | ||
| getCmd.Flags().String("format", "", "Specify an alternative format for the JSON output") | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,92 @@ | ||
| # Using Go text/template for Advanced Data Filtering | ||
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| This document demonstrates the usage of the Go text/template package to filter and format the output of the `ovp8xx get` command for manipulating the result data. There are two custom functions created to enhance the filtering: `prefix` and `toJSON`. | ||
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| ## The `prefix` Function | ||
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| The `prefix` function is designed to solve the problem of trailing commas, which are, for example, not allowed in JSON. The idea is to prefix each line with a comma, except for the very first one. This function is particularly useful when generating JSON output dynamically, where the number of elements may vary. | ||
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| Here's how it's used in the command: | ||
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| ```sh | ||
| ovp8xx get --format '{ "ports": { {{$p := prefix ", "}}{{- range $key, $val := .ports -}}{{call $p}}"{{- $key -}}":{"state": "{{ .state }}"}{{- end }} } }' | ||
| ``` | ||
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| In this command, `{{$p := prefix ", "}}` initializes the prefix function with a comma and a space. Then, `{{call $p}}` is used to insert the prefix before each port entry. The prefix function ensures that no comma is inserted before the first entry. | ||
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| The result is a JSON object where each line, except the first, is prefixed with a comma: | ||
|
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| ```sh | ||
| { | ||
| "ports": { | ||
| "port0": { | ||
| "state": "RUN" | ||
| }, | ||
| "port1": { | ||
| "state": "RUN" | ||
| }, | ||
| "port2": { | ||
| "state": "RUN" | ||
| }, | ||
| "port3": { | ||
| "state": "RUN" | ||
| }, | ||
| "port6": { | ||
| "state": "RUN" | ||
| } | ||
| } | ||
| } | ||
| ``` | ||
|
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| ## Print all ports with some details | ||
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| The following command retrieves all port data and formats it for easy reading: | ||
|
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| ```sh | ||
| ovp8xx get --format '{{$p := prefix "\n"}}{{ range $port, $details := .ports }}{{call $p}}[{{ $port }}] state: {{ $details.state }},{{print "\t"}}type: {{ $details.info.features.type }},{{print "\t"}}PCIC Port: {{ $details.data.pcicTCPPort }}{{ end }}' | ||
| ``` | ||
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| The result will look like: | ||
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| ``` | ||
| [port0] state: RUN, type: 3D, PCIC Port: 50010 | ||
| [port1] state: RUN, type: 3D, PCIC Port: 50011 | ||
| [port2] state: RUN, type: 2D, PCIC Port: 50012 | ||
| [port3] state: RUN, type: 2D, PCIC Port: 50013 | ||
| [port6] state: RUN, type: IMU, PCIC Port: 50016 | ||
| ``` | ||
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| ## Modify the state of the ports | ||
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| Now we are taking the example from the [`prefix`](#the-prefix-function) function and enhance it to also modify the state of all ports (except port6) to CONF with the following command: | ||
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| ```sh | ||
| ovp8xx get --format '{{ $state := "CONF" }}{ "ports": { {{$p := prefix ", "}}{{- range $key, $val := .ports -}}{{ if ne $key "port6" }}{{call $p}}"{{- $key -}}":{"state": "{{ $state }}"}{{end}}{{- end }} } }' | ||
| ``` | ||
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| The output will be a JSON object that can be directly piped into the set command: | ||
|
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| ```sh | ||
| { | ||
| "ports": { | ||
| "port0": { | ||
| "state": "CONF" | ||
| }, | ||
| "port1": { | ||
| "state": "CONF" | ||
| }, | ||
| "port2": { | ||
| "state": "CONF" | ||
| }, | ||
| "port3": { | ||
| "state": "CONF" | ||
| } | ||
| } | ||
| } | ||
| ``` | ||
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| To directly apply those changes to the device, use the following command: | ||
|
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| ```sh | ||
| ovp8xx get --format '{{ $state := "CONF" }}{ "ports": { {{$p := prefix ", "}}{{- range $key, $val := .ports -}}{{ if ne $key "port6" }}{{call $p}}"{{- $key -}}":{"state": "{{ $state }}"}{{end}}{{- end }} } }' | ovp8xx set | ||
| ``` |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,46 @@ | ||
| // Package versioninfo uses runtime.ReadBuildInfo() to set global executable revision information if possible. | ||
| package versioninfo | ||
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| // SPDX-License-Identifier: MIT | ||
| // Copyright (c) 2021 Carl Johnson | ||
| // Based on https://github.com/earthboundkid/versioninfo | ||
|
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| import ( | ||
| "runtime/debug" | ||
| "time" | ||
| ) | ||
|
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| var ( | ||
| // Version will be the version tag if the binary is built with "go install url/tool@version". | ||
| // If the binary is built some other way, it will be "(devel)". | ||
| Version = "unknown" | ||
| // Revision is taken from the vcs.revision tag in Go 1.18+. | ||
| Revision = "unknown" | ||
| // LastCommit is taken from the vcs.time tag in Go 1.18+. | ||
| LastCommit time.Time | ||
| // DirtyBuild is taken from the vcs.modified tag in Go 1.18+. | ||
| DirtyBuild = true | ||
| ) | ||
|
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| func init() { | ||
| info, ok := debug.ReadBuildInfo() | ||
| if !ok { | ||
| return | ||
| } | ||
| for _, kv := range info.Settings { | ||
| if kv.Value == "" { | ||
| continue | ||
| } | ||
| switch kv.Key { | ||
| case "vcs.revision": | ||
| Revision = kv.Value | ||
| case "vcs.time": | ||
| LastCommit, _ = time.Parse(time.RFC3339, kv.Value) | ||
| case "vcs.modified": | ||
| DirtyBuild = kv.Value == "true" | ||
| } | ||
| } | ||
| if info.Main.Version != "" { | ||
| Version = info.Main.Version | ||
| } | ||
| } |