Add --include option to display columns selectively

Signed-off-by: aswinkarthik <aswinkarthik93@gmail.com>

cmd/config.go

@@ -15,9 +15,10 @@ func init() {
 
 // Config is to store all command line Flags.
 type Config struct {
-	PrimaryKeyPositions  []int
-	ValueColumnPositions []int
-	Format               string
+	PrimaryKeyPositions    []int
+	ValueColumnPositions   []int
+	IncludeColumnPositions []int
+	Format                 string
 }
 
 // GetPrimaryKeys is to return the --primary-key flags as digest.Positions array.
@@ -28,14 +29,23 @@ func (c *Config) GetPrimaryKeys() digest.Positions {
 	return []int{0}
 }
 
-// GetValueColumns is to return the --value-columns flags as digest.Positions array.
+// GetValueColumns is to return the --columns flags as digest.Positions array.
 func (c *Config) GetValueColumns() digest.Positions {
 	if len(c.ValueColumnPositions) > 0 {
 		return c.ValueColumnPositions
 	}
 	return []int{}
 }
 
+// GetIncludeColumnPositions is to return the --include flags as digest.Positions array.
+// If empty, it is value columns
+func (c *Config) GetIncludeColumnPositions() digest.Positions {
+	if len(c.IncludeColumnPositions) > 0 {
+		return c.IncludeColumnPositions
+	}
+	return c.GetValueColumns()
+}
+
 // Validate validates the config object
 // and returns error if not valid.
 func (c *Config) Validate() error {

cmd/root.go

@@ -27,9 +27,7 @@ import (
 	"time"
 
 	"github.com/aswinkarthik/csvdiff/pkg/digest"
-	homedir "github.com/mitchellh/go-homedir"
 	"github.com/spf13/cobra"
-	"github.com/spf13/viper"
 )
 
 var (
@@ -70,8 +68,6 @@ Most suitable for csv files created from database tables`,
 
 		return nil
 	},
-	// Uncomment the following line if your bare application
-	// has an action associated with it:
 	Run: func(cmd *cobra.Command, args []string) {
 		// Print version and exit program
 		if version {
@@ -88,8 +84,18 @@ Most suitable for csv files created from database tables`,
 		deltaFile := newReadCloser(args[1])
 		defer deltaFile.Close()
 
-		baseConfig := digest.NewConfig(baseFile, config.GetPrimaryKeys(), config.GetValueColumns())
-		deltaConfig := digest.NewConfig(deltaFile, config.GetPrimaryKeys(), config.GetValueColumns())
+		baseConfig := digest.NewConfig(
+			baseFile,
+			config.GetPrimaryKeys(),
+			config.GetValueColumns(),
+			config.GetIncludeColumnPositions(),
+		)
+		deltaConfig := digest.NewConfig(
+			deltaFile,
+			config.GetPrimaryKeys(),
+			config.GetValueColumns(),
+			config.GetIncludeColumnPositions(),
+		)
 
 		diff, err := digest.Diff(baseConfig, deltaConfig)
 
@@ -126,57 +132,23 @@ func isValidFile(path string) error {
 // This is called by main.main(). It only needs to happen once to the rootCmd.
 func Execute() {
 	if err := rootCmd.Execute(); err != nil {
-		fmt.Println(err)
+		fmt.Fprintf(os.Stderr, "%v", err)
 		os.Exit(1)
 	}
 }
 
 func init() {
-	cobra.OnInitialize(initConfig)
-
-	// Here you will define your flags and configuration settings.
-	// Cobra supports persistent flags, which, if defined here,
-	// will be global for your application.
-	rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.csvdiff.yaml)")
-
-	// Cobra also supports local flags, which will only run
-	// when this action is called directly.
 	rootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
 
 	rootCmd.Flags().IntSliceVarP(&config.PrimaryKeyPositions, "primary-key", "p", []int{0}, "Primary key positions of the Input CSV as comma separated values Eg: 1,2")
 	rootCmd.Flags().IntSliceVarP(&config.ValueColumnPositions, "columns", "", []int{}, "Selectively compare positions in CSV Eg: 1,2. Default is entire row")
+	rootCmd.Flags().IntSliceVarP(&config.IncludeColumnPositions, "include", "", []int{}, "Include positions in CSV to display Eg: 1,2. Default is entire row")
 	rootCmd.Flags().StringVarP(&config.Format, "format", "", "rowmark", "Available (rowmark|json)")
 
 	rootCmd.Flags().BoolVarP(&timed, "time", "", false, "Measure time")
 	rootCmd.Flags().BoolVarP(&version, "version", "", false, "Display version")
 }
 
-// initConfig reads in config file and ENV variables if set.
-func initConfig() {
-	if cfgFile != "" {
-		// Use config file from the flag.
-		viper.SetConfigFile(cfgFile)
-	} else {
-		// Find home directory.
-		home, err := homedir.Dir()
-		if err != nil {
-			fmt.Println(err)
-			os.Exit(1)
-		}
-
-		// Search config in home directory with name ".csvdiff" (without extension).
-		viper.AddConfigPath(home)
-		viper.SetConfigName(".csvdiff")
-	}
-
-	viper.AutomaticEnv() // read in environment variables that match
-
-	// If a config file is found, read it in.
-	if err := viper.ReadInConfig(); err == nil {
-		fmt.Println("Using config file:", viper.ConfigFileUsed())
-	}
-}
-
 func newReadCloser(filename string) io.ReadCloser {
 	file, err := os.Open(filename)
 	if err != nil {

pkg/digest/compare.go

@@ -4,7 +4,6 @@ import (
 	"encoding/csv"
 	"fmt"
 	"runtime"
-	"strings"
 	"sync"
 )
 
@@ -100,17 +99,19 @@ func compareDigestForNLines(base map[uint64]uint64,
 		if baseValue, present := base[digest.Key]; present {
 			// Present in both base and delta
 			if baseValue != digest.Value {
+				value := config.Include.MapToValue(line)
 				// Modification
 				output[diffCounter] = diffMessage{
-					value: strings.Join(line, Separator),
+					value: value,
 					_type: modification,
 				}
 				diffCounter++
 			}
 		} else {
+			value := config.Include.MapToValue(line)
 			// Not present in base. So Addition.
 			output[diffCounter] = diffMessage{
-				value: strings.Join(line, Separator),
+				value: value,
 				_type: addition,
 			}
 			diffCounter++

pkg/digest/compare_test.go

@@ -18,34 +18,97 @@ func TestDiff(t *testing.T) {
 	delta := `1,col-1,col-2,col-3,one-value
 2,col-1,col-2,col-3,two-value-modified
 4,col-1,col-2,col-3,four-value-added
-100,col-1,col-2,col-3,hundred-value-modified
+100,col-1-modified,col-2,col-3,hundred-value-modified
 5,col-1,col-2,col-3,five-value-added
 `
 
-	baseConfig := &digest.Config{
-		Reader: strings.NewReader(base),
-		Key:    []int{0},
-	}
-
-	deltaConfig := &digest.Config{
-		Reader: strings.NewReader(delta),
-		Key:    []int{0},
-	}
-
-	expected := digest.Difference{
-		Additions: []string{
-			"4,col-1,col-2,col-3,four-value-added",
-			"5,col-1,col-2,col-3,five-value-added",
-		},
-		Modifications: []string{
-			"2,col-1,col-2,col-3,two-value-modified",
-			"100,col-1,col-2,col-3,hundred-value-modified",
-		},
-	}
-
-	actual, err := digest.Diff(baseConfig, deltaConfig)
-
-	assert.NoError(t, err)
-	assert.ElementsMatch(t, expected.Modifications, actual.Modifications)
-	assert.ElementsMatch(t, expected.Additions, actual.Additions)
+	t.Run("default config", func(t *testing.T) {
+		baseConfig := &digest.Config{
+			Reader: strings.NewReader(base),
+			Key:    []int{0},
+		}
+
+		deltaConfig := &digest.Config{
+			Reader: strings.NewReader(delta),
+			Key:    []int{0},
+		}
+
+		expected := digest.Difference{
+			Additions: []string{
+				"4,col-1,col-2,col-3,four-value-added",
+				"5,col-1,col-2,col-3,five-value-added",
+			},
+			Modifications: []string{
+				"2,col-1,col-2,col-3,two-value-modified",
+				"100,col-1-modified,col-2,col-3,hundred-value-modified",
+			},
+		}
+
+		actual, err := digest.Diff(baseConfig, deltaConfig)
+
+		assert.NoError(t, err)
+		assert.ElementsMatch(t, expected.Modifications, actual.Modifications)
+		assert.ElementsMatch(t, expected.Additions, actual.Additions)
+	})
+
+	t.Run("selective values columns", func(t *testing.T) {
+		baseConfig := &digest.Config{
+			Reader: strings.NewReader(base),
+			Key:    []int{0},
+			Value:  []int{1},
+		}
+
+		deltaConfig := &digest.Config{
+			Reader: strings.NewReader(delta),
+			Key:    []int{0},
+			Value:  []int{1},
+		}
+
+		expected := digest.Difference{
+			Additions: []string{
+				"4,col-1,col-2,col-3,four-value-added",
+				"5,col-1,col-2,col-3,five-value-added",
+			},
+			Modifications: []string{
+				"100,col-1-modified,col-2,col-3,hundred-value-modified",
+			},
+		}
+
+		actual, err := digest.Diff(baseConfig, deltaConfig)
+
+		assert.NoError(t, err)
+		assert.ElementsMatch(t, expected.Modifications, actual.Modifications)
+		assert.ElementsMatch(t, expected.Additions, actual.Additions)
+	})
+
+	t.Run("selective include columns", func(t *testing.T) {
+		baseConfig := &digest.Config{
+			Reader:  strings.NewReader(base),
+			Key:     []int{0},
+			Include: []int{0},
+		}
+
+		deltaConfig := &digest.Config{
+			Reader:  strings.NewReader(delta),
+			Key:     []int{0},
+			Include: []int{0},
+		}
+
+		expected := digest.Difference{
+			Additions: []string{
+				"4",
+				"5",
+			},
+			Modifications: []string{
+				"2",
+				"100",
+			},
+		}
+
+		actual, err := digest.Diff(baseConfig, deltaConfig)
+
+		assert.NoError(t, err)
+		assert.ElementsMatch(t, expected.Modifications, actual.Modifications)
+		assert.ElementsMatch(t, expected.Additions, actual.Additions)
+	})
 }

pkg/digest/digest.go

@@ -31,18 +31,28 @@ func CreateDigest(csv []string, pKey Positions, pRow Positions) Digest {
 
 // Config represents configurations that can be passed
 // to create a Digest.
+//
+// Key: The primary key positions
+// Value: The Value positions that needs to be compared for diff
+// Include: Include these positions in output. It is Value positions by default.
 type Config struct {
-	Key    Positions
-	Value  Positions
-	Reader io.Reader
+	Key     Positions
+	Value   Positions
+	Include Positions
+	Reader  io.Reader
 }
 
 // NewConfig creates an instance of Config struct.
-func NewConfig(r io.Reader, primaryKey Positions, valueColumns Positions) *Config {
+func NewConfig(r io.Reader, primaryKey Positions, valueColumns Positions, includeColumns Positions) *Config {
+	if len(includeColumns) == 0 {
+		includeColumns = valueColumns
+	}
+
 	return &Config{
-		Reader: r,
-		Key:    primaryKey,
-		Value:  valueColumns,
+		Reader:  r,
+		Key:     primaryKey,
+		Value:   valueColumns,
+		Include: includeColumns,
 	}
 }
 

pkg/digest/positions.go

@@ -1,6 +1,8 @@
 package digest
 
-import "strings"
+import (
+	"strings"
+)
 
 // Positions represents positions of columns in a CSV array.
 type Positions []int
@@ -12,9 +14,35 @@ func (p Positions) MapToValue(csv []string) string {
 	if len(p) == 0 {
 		return strings.Join(csv, Separator)
 	}
-	output := make([]string, len(p))
-	for i, pos := range p {
-		output[i] = csv[pos]
+
+	csvStr := strings.Builder{}
+	for _, pos := range p[:len(p)-1] {
+		csvStr.WriteString(csv[pos])
+		csvStr.WriteString(Separator)
 	}
-	return strings.Join(output, Separator)
+	csvStr.WriteString(csv[p[len(p)-1]])
+	return csvStr.String()
+}
+
+// Append additional positions to existing positions.
+// Imp: Removes Duplicate. Does not mutate the original array
+func (p Positions) Append(additional Positions) Positions {
+	for _, toBeAdded := range additional {
+		if !p.Contains(toBeAdded) {
+			p = append(p, toBeAdded)
+		}
+	}
+
+	return p
+}
+
+// Contains returns true if position is already present in Positions
+func (p Positions) Contains(position int) bool {
+	for _, each := range p {
+		if each == position {
+			return true
+		}
+	}
+
+	return false
 }

pkg/digest/positions_test.go

@@ -27,3 +27,19 @@ func TestPositionsMapValuesReturnsCompleteStringCsvIfEmpty(t *testing.T) {
 
 	assert.Equal(t, expected, actual)
 }
+
+func TestPosition_Contains(t *testing.T) {
+	positions := digest.Positions([]int{0, 3})
+
+	assert.True(t, positions.Contains(3))
+	assert.False(t, positions.Contains(4))
+}
+
+func TestPosition_Append(t *testing.T) {
+	positions := digest.Positions([]int{0, 3})
+	additionalPositions := digest.Positions([]int{4, 3})
+
+	positions = positions.Append(additionalPositions)
+
+	assert.ElementsMatch(t, []int{0, 3, 4}, []int(positions))
+}