New feature: YAML<->JSON transformation

README.md

@@ -21,12 +21,14 @@ Limner colorizes and transforms CLI outputs.
 
 When playing with `kubectl`, I sometimes found it hard to extract the information I needed most from the extermely **long, mono-colored** output produced by the CLI. The same things happens when I'm using `curl` to test some REST APIs which usually return a long string of JSON.
 
-Of course I can use GUI tools like *Kubernetes Dashboard* and *Postman*, but for simple operations that need to be performed swiftly, CLIs have their own advantages. Therefore, I made limner to bring some changes to the CLIs' output.
+Of course I can use GUI tools like _Kubernetes Dashboard_ and _Postman_, but for simple operations that need to be performed swiftly, CLIs have their own advantages. Therefore, I made limner to bring some changes to the CLIs' output.
 
 ## Installation
 
 ### Download a release binary
+
 Go to [Release Page](https://github.com/SignorMercurio/limner/releases), download a release and run:
+
 ```bash
 tar zxvf lm_[version]_[os]_[arch].tar.gz
 cd lm_[version]_[os]_[arch]
@@ -42,13 +44,15 @@ Remember to replace the text in `[]`.
 1. You'll need Go [installed](https://golang.org/doc/install).
 
 2. Clone the repo:
+
 ```bash
 git clone https://github.com/SignorMercurio/limner.git
 cd limner
 go build -o lm .
 ```
 
 3. Run the command:
+
 ```bash
 [your command] | ./lm
 ```
@@ -61,35 +65,60 @@ go build -o lm .
 
 In most cases, you don't need to append any arguments when using limner as it automatically detects the format of the output.
 
-Colorize tables:
+#### Colorize tables
 
 ```bash
 kubectl get po | lm
 ```
 
-Colorize YAML files:
+![Table colorization](img/table.png)
+
+#### Colorize YAML files
+
+```bash
+kubectl describe deploy/nginx | lm
+```
+
+![YAML colorization](img/yml.png)
+
+#### Colorize JSON responses
 
 ```bash
-cat nginx-deploy.yml | lm
+curl -s https://api.github.com/users/SignorMercurio | lm
 ```
 
-Colorize JSON responses:
+![JSON colorization](img/json.png)
+
+#### Transform YAML to JSON
 
 ```bash
-curl https://api.github.com/users/SignorMercurio | lm
+cat nginx/deploy.yml | lm tr -i yaml -o json
 ```
 
+You can always omit `-i yaml` as long as the format of input is YAML.
+
+![YAML->JSON transformation](img/yml2json.png)
+
+#### Transform JSON to YAML
+
+```bash
+curl -s https://jsonplaceholder.typicode.com/users/1/albums | lm tr -o yml
+```
+
+![JSON->YAML transformation](img/json2yml.png)
+
 > TODO: Add support for more formats and transformation between different formats.
 
 ### Create a shortcut
 
-Take `kubectl` as an example. 
+Take `kubectl` as an example.
 
 #### Bash
 
 Suppose you've already [configured autocompletion](https://kubernetes.io/docs/tasks/tools/included/optional-kubectl-configs-bash-linux/) for `kubectl` (Optional).
 
 In your `.bash_profile` or `.bashrc`, append the following lines:
+
 ```bash
 function k() {kubectl $@ | lm}
 complete -o default -F __start_kubectl k
@@ -100,15 +129,15 @@ complete -o default -F __start_kubectl k
 Suppose you've already [configured autocompletion](https://kubernetes.io/docs/tasks/tools/included/optional-kubectl-configs-zsh/) for `kubectl` (Optional).
 
 In your `.zprofile` or `.zshrc`, append the following lines:
+
 ```bash
 function k() {kubectl $@ | lm}
 compdef k=kubectl
 ```
 
 After the above steps, you'll be able to use `kubectl` with color and autocompletion like:
-```bash
-k get po
-```
+
+![Using a shortcut](img/shortcut.png)
 
 ### Non-terminal output
 
@@ -166,8 +195,8 @@ Thank you for willing to contribute to this project!
   - [x] JSON
   - [x] Tables
   - [ ] ...
-- [ ] Simple data format transformation
-  - [ ] YAML <-> JSON
+- [x] Simple data format transformation
+  - [x] YAML <-> JSON
   - [ ] ...
 
 If you have any suggestions for the project, please don't hesitate to open an [issue](https://github.com/SignorMercurio/limner/issues) or [pull request](https://github.com/SignorMercurio/limner/pulls).

cmd/tr.go

@@ -27,7 +27,8 @@ func NewTrCmd() *cobra.Command {
 		Short: "tr helps to transform data format",
 		Long: `tr helps to transform data format
 Example:
-	curl -s https://api.github.com/users/SignorMercurio | lm tr -i json -o yaml ("-i json" can be omitted)`,
+	curl -s https://api.github.com/users/SignorMercurio | lm tr -i json -o yaml ("-i json" can be omitted)
+	cat nginx.yml | lm tr -o json`,
 		RunE: func(cmd *cobra.Command, args []string) error {
 			var err error
 			if inType == outType {

printer/color.go

@@ -1,7 +1,6 @@
 package printer
 
 import (
-	"encoding/json"
 	"fmt"
 	"io"
 	"strings"
@@ -15,26 +14,31 @@ type ColorPrinter struct {
 }
 
 func (cp *ColorPrinter) Print(buf string, w io.Writer) {
-	var printer Printer = &SingleColorPrinter{Color: stringColor}
-	var jsonObj map[string]interface{}
+	var (
+		printer Printer = &SingleColorPrinter{Color: stringColor}
+		bufByte         = []byte(buf)
+		jsonObj interface{}
+		isJson  bool
+	)
 
 	// change the printer if type is already enforced
 	switch cp.Type {
 	case "yaml", "yml":
 		printer = NewYamlPrinter()
 	case "json":
-		if err := json.Unmarshal([]byte(buf), &jsonObj); err != nil {
-			fmt.Fprintln(w, color.Apply("Failed to unmarshal json, using default printer", color.Yellow))
-		} else {
+		if jsonObj, isJson = util.ShouldJson(bufByte); isJson {
 			printer = NewJsonPrinter(jsonObj)
+		} else {
+			fmt.Fprintln(w, color.Apply("Failed to unmarshal json, using default printer", color.Yellow))
 		}
 	case "table":
 		printer = NewTablePrinter(ColorStatus)
-		// case "xml":
 	default:
 		// otherwise, try to determine the type
+		// try json first
+		jsonObj, isJson = util.ShouldJson(bufByte)
 		switch {
-		case util.ShouldJson([]byte(buf), &jsonObj):
+		case isJson:
 			printer = NewJsonPrinter(jsonObj)
 		case util.ShouldTable(buf):
 			printer = NewTablePrinter(ColorStatus)

printer/json.go

@@ -10,7 +10,7 @@ import (
 )
 
 type JsonPrinter struct {
-	jsonObj map[string]interface{}
+	jsonObj interface{}
 }
 
 func (jp *JsonPrinter) Print(buf string, w io.Writer) {
@@ -21,7 +21,7 @@ func (jp *JsonPrinter) Print(buf string, w io.Writer) {
 	}
 }
 
-func NewJsonPrinter(jsonObj map[string]interface{}) *JsonPrinter {
+func NewJsonPrinter(jsonObj interface{}) *JsonPrinter {
 	return &JsonPrinter{
 		jsonObj: jsonObj,
 	}

transformer/format.go

@@ -1,5 +1,11 @@
 package transformer
 
+import (
+	"fmt"
+
+	"github.com/SignorMercurio/limner/color"
+)
+
 type FormatTransformer struct {
 	InType  string
 	OutType string
@@ -11,7 +17,13 @@ func (ft *FormatTransformer) Transform(input []byte) ([]byte, error) {
 	switch ft.OutType {
 	case "yaml", "yml":
 		trans = NewYamlTransformer(ft.InType)
+	case "json":
+		trans = NewJsonTransformer(ft.InType)
 	}
 
 	return trans.Transform(input)
 }
+
+func unknownInput() {
+	fmt.Println(color.Apply("Unknown input format, using default transformer", color.Yellow))
+}

transformer/json.go

@@ -0,0 +1,40 @@
+package transformer
+
+import (
+	"encoding/json"
+
+	"github.com/SignorMercurio/limner/util"
+	"gopkg.in/yaml.v3"
+)
+
+type JsonTransformer struct {
+	Type string
+	obj  util.Obj
+}
+
+func (jt *JsonTransformer) Transform(input []byte) ([]byte, error) {
+	// fill the obj if the type is already enforced
+	switch jt.Type {
+	case "yaml":
+		if err := yaml.Unmarshal(input, &jt.obj); err == nil {
+			return json.MarshalIndent(jt.obj, "", "    ")
+		}
+	default:
+		// otherwise, try to determine the type
+		switch {
+		case util.ShouldYaml(string(input)):
+			if err := yaml.Unmarshal(input, &jt.obj); err == nil {
+				return json.MarshalIndent(jt.obj, "", "    ")
+			}
+		}
+	}
+
+	unknownInput()
+	return input, nil
+}
+
+func NewJsonTransformer(Type string) *JsonTransformer {
+	return &JsonTransformer{
+		Type: Type,
+	}
+}