Feature: Adds merge command

Adds merge command for merging multiple yaml files together.

Resolves: #31

README.md

@@ -20,6 +20,8 @@ go get github.com/mikefarah/yaml
 - Convert from json to yaml
 - Convert from yaml to json
 - Pipe data in by using '-'
+- Merge multiple yaml files where each additional file sets values for missing or null value keys.
+- Merge multiple yaml files with overwrite to support overriding previous values.
 
 ## [Usage](http://mikefarah.github.io/yaml/)
 
@@ -30,15 +32,17 @@ Usage:
   yaml [command]
 
 Available Commands:
+  help        Help about any command
+  merge       yaml m [--inplace/-i] [--overwrite/-x] sample.yaml sample2.yaml
+  new         yaml n [--script/-s script_file] a.b.c newValueForC
   read        yaml r sample.yaml a.b.c
   write       yaml w [--inplace/-i] [--script/-s script_file] sample.yaml a.b.c newValueForC
-  new         yaml n [--script/-s script_file] a.b.c newValueForC
 
 Flags:
-  -h, --help[=false]: help for yaml
-  -j, --tojson[=false]: output as json
-  -t, --trim[=true]: trim yaml output
-  -v, --verbose[=false]: verbose mode
+  -h, --help      help for yaml
+  -j, --tojson    output as json
+  -t, --trim      trim yaml output (default true)
+  -v, --verbose   verbose mode
 
 Use "yaml [command] --help" for more information about a command.
 ```

commands_test.go

@@ -303,3 +303,74 @@ func TestWriteCmd_Inplace(t *testing.T) {
   c: 7`
 	assertResult(t, expectedOutput, gotOutput)
 }
+
+func TestMergeCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "merge examples/data1.yaml examples/data2.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: simple
+b:
+- 1
+- 2
+c:
+  test: 1
+`
+	assertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeCmd_Error(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "merge examples/data1.yaml")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to missing arg")
+	}
+	expectedOutput := `Must provide at least 2 yaml files`
+	assertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestMergeCmd_ErrorUnreadableFile(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "merge examples/data1.yaml fake-unknown")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to unknown file")
+	}
+	expectedOutput := `open fake-unknown: no such file or directory`
+	assertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestMergeCmd_Verbose(t *testing.T) {
+	cmd := getRootCommand()
+	result := runCmd(cmd, "-v merge examples/data1.yaml examples/data2.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: simple
+b:
+- 1
+- 2
+c:
+  test: 1
+`
+	assertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeCmd_Inplace(t *testing.T) {
+	filename := writeTempYamlFile(readTempYamlFile("examples/data1.yaml"))
+	defer removeTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := runCmd(cmd, fmt.Sprintf("merge -i %s examples/data2.yaml", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	gotOutput := readTempYamlFile(filename)
+	expectedOutput := `a: simple
+b:
+- 1
+- 2
+c:
+  test: 1`
+	assertResult(t, expectedOutput, gotOutput)
+}

data_navigator.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"sort"
 	"strconv"
 
 	"gopkg.in/yaml.v2"
@@ -175,3 +176,38 @@ func calculateValue(value interface{}, tail []string) (interface{}, error) {
 	}
 	return value, nil
 }
+
+func mapToMapSlice(data map[interface{}]interface{}) yaml.MapSlice {
+	var mapSlice yaml.MapSlice
+
+	for k, v := range data {
+		if mv, ok := v.(map[interface{}]interface{}); ok {
+			v = mapToMapSlice(mv)
+		}
+		item := yaml.MapItem{Key: k, Value: v}
+		mapSlice = append(mapSlice, item)
+	}
+
+	// because the parsing of the yaml was done via a map the order will be inconsistent
+	// apply order to allow a consistent output
+	// Only available in Go 1.8+
+	// sort.SliceStable(mapSlice, func(i, j int) bool { return mapSlice[i].Key < mapSlice[j].Key })
+	sort.Sort(sortMap{mapSlice})
+	return mapSlice
+}
+
+type sortMap struct {
+	ms yaml.MapSlice
+}
+
+func (m sortMap) Len() int {
+	return len(m.ms)
+}
+
+func (m sortMap) Less(i, j int) bool {
+	return m.ms[i].Key.(string) < m.ms[j].Key.(string)
+}
+
+func (m sortMap) Swap(i, j int) {
+	m.ms[i], m.ms[j] = m.ms[j], m.ms[i]
+}

examples/data1.yaml

@@ -0,0 +1,2 @@
+a: simple
+b: [1, 2]

examples/data2.yaml

@@ -0,0 +1,3 @@
+a: other
+c:
+  test: 1

examples/data3.yaml

@@ -0,0 +1,5 @@
+b: [2, 3, 4]
+c:
+  test: 2
+  other: true
+d: false

merge.go

@@ -0,0 +1,12 @@
+package main
+
+import (
+	"github.com/imdario/mergo"
+)
+
+func merge(dst, src interface{}, overwrite bool) error {
+	if overwrite {
+		return mergo.MergeWithOverwrite(dst, src)
+	}
+	return mergo.Merge(dst, src)
+}

merge_test.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"testing"
+
+	yaml "gopkg.in/yaml.v2"
+)
+
+func TestMerge(t *testing.T) {
+	result, _ := mergeYaml([]string{"examples/data1.yaml", "examples/data2.yaml", "examples/data3.yaml"})
+	expected := yaml.MapSlice{
+		yaml.MapItem{Key: "a", Value: "simple"},
+		yaml.MapItem{Key: "b", Value: []interface{}{1, 2}},
+		yaml.MapItem{Key: "c", Value: yaml.MapSlice{yaml.MapItem{Key: "other", Value: true}, yaml.MapItem{Key: "test", Value: 1}}},
+		yaml.MapItem{Key: "d", Value: false},
+	}
+	assertResultComplex(t, expected, result)
+}
+
+func TestMergeWithOverwrite(t *testing.T) {
+	overwriteFlag = true
+	result, _ := mergeYaml([]string{"examples/data1.yaml", "examples/data2.yaml", "examples/data3.yaml"})
+	expected := yaml.MapSlice{
+		yaml.MapItem{Key: "a", Value: "other"},
+		yaml.MapItem{Key: "b", Value: []interface{}{2, 3, 4}},
+		yaml.MapItem{Key: "c", Value: yaml.MapSlice{yaml.MapItem{Key: "other", Value: true}, yaml.MapItem{Key: "test", Value: 2}}},
+		yaml.MapItem{Key: "d", Value: false},
+	}
+	assertResultComplex(t, expected, result)
+}

scripts/vendor.sh

@@ -5,4 +5,5 @@ set -e
 govendor fetch github.com/op/go-logging
 govendor fetch github.com/spf13/cobra
 govendor fetch gopkg.in/yaml.v2
+govendor fetch github.com/imdario/mergo
 govendor sync

vendor/vendor.json

@@ -2,6 +2,12 @@
 	"comment": "",
 	"ignore": "test",
 	"package": [
+		{
+			"checksumSHA1": "66lykxpWgSmQodnhkADqn6tnroQ=",
+			"path": "github.com/imdario/mergo",
+			"revision": "e3000cb3d28c72b837601cac94debd91032d19fe",
+			"revisionTime": "2017-06-20T10:47:01Z"
+		},
 		{
 			"checksumSHA1": "40vJyUB4ezQSn/NSadsKEOrudMc=",
 			"path": "github.com/inconshreveable/mousetrap",

yaml.go

@@ -17,6 +17,7 @@ var trimOutput = true
 var writeInplace = false
 var writeScript = ""
 var outputToJSON = false
+var overwriteFlag = false
 var verbose = false
 var log = logging.MustGetLogger("yaml")
 
@@ -52,7 +53,7 @@ func newCommandCLI() *cobra.Command {
 	rootCmd.PersistentFlags().BoolVarP(&outputToJSON, "tojson", "j", false, "output as json")
 	rootCmd.PersistentFlags().BoolVarP(&verbose, "verbose", "v", false, "verbose mode")
 
-	rootCmd.AddCommand(createReadCmd(), createWriteCmd(), createNewCmd())
+	rootCmd.AddCommand(createReadCmd(), createWriteCmd(), createNewCmd(), createMergeCmd())
 	rootCmd.SetOutput(os.Stdout)
 
 	return rootCmd
@@ -127,6 +128,30 @@ Note that you can give a create script to perform more sophisticated yaml. This
 	return cmdNew
 }
 
+func createMergeCmd() *cobra.Command {
+	var cmdMerge = &cobra.Command{
+		Use:     "merge [initial_yaml_file] [additional_yaml_file]...",
+		Aliases: []string{"m"},
+		Short:   "yaml m [--inplace/-i] [--overwrite/-x] sample.yaml sample2.yaml",
+		Example: `
+yaml merge things.yaml other.yaml
+yaml merge --inplace things.yaml other.yaml
+yaml m -i things.yaml other.yaml
+yaml m --overwrite things.yaml other.yaml
+yaml m -i -x things.yaml other.yaml
+      `,
+		Long: `Updates the yaml file by adding/updating the path(s) and value(s) from additional yaml file(s).
+Outputs to STDOUT unless the inplace flag is used, in which case the file is updated instead.
+
+If overwrite flag is set then existing values will be overwritten using the values from each additional yaml file.
+`,
+		RunE: mergeProperties,
+	}
+	cmdMerge.PersistentFlags().BoolVarP(&writeInplace, "inplace", "i", false, "update the yaml file inplace")
+	cmdMerge.PersistentFlags().BoolVarP(&overwriteFlag, "overwrite", "x", false, "update the yaml file by overwriting existing values")
+	return cmdMerge
+}
+
 func readProperty(cmd *cobra.Command, args []string) error {
 	data, err := read(args)
 	if err != nil {
@@ -233,6 +258,34 @@ func write(cmd *cobra.Command, filename string, updatedData interface{}) error {
 	return nil
 }
 
+func mergeProperties(cmd *cobra.Command, args []string) error {
+	if len(args) < 2 {
+		return errors.New("Must provide at least 2 yaml files")
+	}
+
+	updatedData, err := mergeYaml(args)
+	if err != nil {
+		return err
+	}
+	return write(cmd, args[0], updatedData)
+}
+
+func mergeYaml(args []string) (interface{}, error) {
+	var updatedData map[interface{}]interface{}
+
+	for _, f := range args {
+		var parsedData map[interface{}]interface{}
+		if err := readData(f, &parsedData); err != nil {
+			return nil, err
+		}
+		if err := merge(&updatedData, parsedData, overwriteFlag); err != nil {
+			return nil, err
+		}
+	}
+
+	return mapToMapSlice(updatedData), nil
+}
+
 func updateParsedData(parsedData yaml.MapSlice, writeCommands yaml.MapSlice, prependCommand string) (interface{}, error) {
 	var prefix = ""
 	if prependCommand != "" {