Add ability to execute a command for each generated file

README.md

@@ -22,7 +22,6 @@ An example of `nerc.yml` file:
 ```yaml
 input: test_data/products.csv       # Defines the CSV input filepath
 templates: test_data/templates/   # Defines the dirpath of the template files
-output: output/                     # Defines the output dirpath
 variables:                          # Defines template variables
   - key: ProductName                # Defines the variable key or "name"
     csvSourceCol: 6                 # CSV column no for product name
@@ -31,16 +30,29 @@ variables:                          # Defines template variables
     type: price                     # Type of the variable. Price is rendered with two decimals.
   - key: ProductImage
     csvSourceCol: 21
+output: output/                     # Defines the output dirpath
+runCommand: head -1 %s              # Command to be executed if -r flag is given.
 ```
-**input:** Path to the input CSV file
+`input:` Path to the input CSV file
 
-**templates:** Path to the directory that contains the template files. Each template is used to generate
+`templates:` Path to the directory that contains the template files. Each template is used to generate
 an output file per each line in the input CSV file. Templates can use variables defined in `nerc.yml` file
 with `{{.<VariableKey>}}` syntax.
 
-**output:** Output directory path for the generated config files.
+`output:` Output directory path for the generated config files.
 
-**variables:** List of variables that can be used in the templates. Each variable must have `key` and `csvSourceCol`
+`variables:` List of variables that can be used in the templates. Each variable must have `key` and `csvSourceCol`
 which defines the CSV column number where the tools fetches the variable value. Optionally variable can also have
 `type`. Currently only `price` type is supported, which tries to ensure two decimal price.
 
+## Command line flags
+
+`-r`: Use `nerc -r` to execute command using each generated config file as an input for the command. Define the
+executed command in `nerc.yaml` with `runCommand` key e.g. `runCommand: head -1 %s` would call `head -1` command
+for each generated config file and hence output the first line of each file. Note that the `%s` is substituted with
+the template filename.
+
+`-purge`: Cleans the output directory from all files. Everything inside the output directory specified in `nerc.yaml`
+will be removed.
+
+`-v`: Gives more verbose output. 

nerc.go

@@ -12,9 +12,11 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"os/exec"
 	"path"
 	"path/filepath"
 	"strconv"
+	"strings"
 	"text/template"
 )
 
@@ -24,11 +26,12 @@ const PRICE_COL = 14
 
 var purgeOnly bool
 var verbose bool
+var run bool
 
 type TemplateVariable struct {
-	Key          string      `yaml:"key"`
-	CSVSourceCol int         `yaml:"csvSourceCol"`
-	Type         string      `yaml:"type"`
+	Key          string `yaml:"key"`
+	CSVSourceCol int    `yaml:"csvSourceCol"`
+	Type         string `yaml:"type"`
 }
 
 type NercConf struct {
@@ -38,11 +41,13 @@ type NercConf struct {
 	Variables       []TemplateVariable     `yaml:"variables"`
 	StaticVariables map[string]interface{} `yaml:"staticVariables"`
 	CSVMapping      map[string]int         `yaml:"csvMapping"`
+	RunCommand      string                 `yaml:"runCommand"`
 }
 
 func main() {
 	flag.BoolVar(&purgeOnly, "purge", false, "Purge all existing files from output directory and stop.")
 	flag.BoolVar(&verbose, "v", false, "Use verbose output.")
+	flag.BoolVar(&run, "run", false, "Execute runCommand (from nerc.yml) for each generated file.")
 	flag.Parse()
 
 	nercConf := NercConf{}
@@ -72,12 +77,38 @@ func main() {
 			r := csv.NewReader(bufio.NewReader(csvFile))
 			os.Mkdir(nercConf.Output, os.ModePerm)
 			csvToConfigs(r, nercConf)
+			if run && nercConf.RunCommand != "" {
+				runCommandForTemplates(nercConf)
+			}
 		}
 	}
 
 	fmt.Println("Done")
 }
 
+func runCommandForTemplates(conf NercConf) {
+	var files []string
+
+	if _, err := os.Stat(conf.Output); !os.IsNotExist(err) {
+		err := filepath.Walk(conf.Output, visitPath(&files))
+		if err != nil {
+			panic(err)
+		}
+		for _, file := range files {
+			cmdArgs := strings.Fields(fmt.Sprintf(conf.RunCommand, file))
+			cmd := exec.Command(cmdArgs[0], cmdArgs[1:]...)
+			stdout, err := cmd.Output()
+
+			if err != nil {
+				fmt.Println(err.Error())
+				return
+			}
+
+			fmt.Print(string(stdout))
+		}
+	}
+}
+
 func purgeOutput(nercConf NercConf, silent bool) {
 	err := os.RemoveAll(nercConf.Output)
 	if err != nil && !silent {