env.* support and possible to check require field after all config loading

Author: JohnJ255

cleanenv.go

@@ -53,6 +53,10 @@ const (
 	TagEnvPrefix = "env-prefix"
 )
 
+var (
+	RequiredCheck = true
+)
+
 // Setter is an interface for a custom value setter.
 //
 // To implement a custom value setter you need to add a SetValue function to your type that will receive a string raw value:
@@ -75,6 +79,20 @@ type Updater interface {
 	Update() error
 }
 
+type unsupportedFileFormat struct {
+	ftype string
+}
+
+func (e *unsupportedFileFormat) Error() string {
+	return fmt.Sprintf("file format '%s' doesn't supported by the parser", e.ftype)
+}
+
+func newErrorUnsupportedFileFormat(ftype string) *unsupportedFileFormat {
+	return &unsupportedFileFormat{
+		ftype: ftype,
+	}
+}
+
 // ReadConfig reads configuration file and parses it depending on tags in structure provided.
 // Then it reads and parses
 //
@@ -134,8 +152,27 @@ func parseFile(path string, cfg interface{}) error {
 	}
 	defer f.Close()
 
+	ftype := "."
+	for ftype != "" {
+		ftype = strings.ToLower(filepath.Ext(path))
+		err = parseFileByType(ftype, f, cfg)
+		if err != nil {
+			if _, ok := err.(*unsupportedFileFormat); ok {
+				path = strings.TrimSuffix(path, filepath.Ext(path))
+			} else {
+				return fmt.Errorf("config file parsing error: %s", err.Error())
+			}
+		} else {
+			ftype = ""
+		}
+	}
+
+	return nil
+}
+
+func parseFileByType(ftype string, f *os.File, cfg interface{}) (err error) {
 	// parse the file depending on the file type
-	switch ext := strings.ToLower(filepath.Ext(path)); ext {
+	switch ftype {
 	case ".yaml", ".yml":
 		err = ParseYAML(f, cfg)
 	case ".json":
@@ -147,12 +184,9 @@ func parseFile(path string, cfg interface{}) error {
 	case ".env":
 		err = parseENV(f, cfg)
 	default:
-		return fmt.Errorf("file format '%s' doesn't supported by the parser", ext)
-	}
-	if err != nil {
-		return fmt.Errorf("config file parsing error: %s", err.Error())
+		return newErrorUnsupportedFileFormat(ftype)
 	}
-	return nil
+	return err
 }
 
 // ParseYAML parses YAML from reader to data structure
@@ -428,7 +462,7 @@ func readEnvVars(cfg interface{}, update bool) error {
 			}
 		}
 
-		if rawValue == nil && meta.required && meta.isFieldValueZero() {
+		if RequiredCheck && rawValue == nil && meta.required && meta.isFieldValueZero() {
 			return fmt.Errorf(
 				"field %q is required but the value is not provided",
 				meta.fieldName,

example/parse_multiple_files/.env.local

@@ -0,0 +1,2 @@
+DB_PORT=5435
+DB_PASSWORD=password

example/parse_multiple_files/README.md

@@ -1,5 +1,5 @@
 # Parse multiple files for configuration
 
-This example shows how the package can be used to read from mutiple configuration files and assign them to the same structure.
+This example shows how the package can be used to read from multiple configuration files and assign them to the same structure.
 
 In this example, the configuration is read from ```db_config.yaml```,```email_config.yaml``` and ```general_config.yaml``` and the values are stored in the ```config``` struct.

example/parse_multiple_files/db_config.yaml

@@ -1,7 +1,6 @@
 database:
   host: "localhost"
   user: "root"
-  password: "password"
   name: "cleanenv"
   port: "5432"
   ssl_mode: "disable"

example/parse_multiple_files/main.go

@@ -15,10 +15,10 @@ type config struct {
 
 type databaseConfig struct {
 	User     string `yaml:"user"`
-	Password string `yaml:"password"`
+	Password string `env-required:"true" yaml:"password" env:"DB_PASSWORD"`
 	Name     string `yaml:"name"`
 	Host     string `yaml:"host"`
-	Port     string `yaml:"port"`
+	Port     string `yaml:"port" env:"DB_PORT"`
 	SSLMode  string `yaml:"ssl_mode"`
 }
 
@@ -28,7 +28,7 @@ type emailService struct {
 }
 
 func main() {
-	cfg, err := ParseConfigFiles("./db_config.yaml", "./email_config.yaml", "./general_config.yaml")
+	cfg, err := ParseConfigFiles("./db_config.yaml", "./email_config.yaml", "./general_config.yaml", "./.env.local")
 	if err != nil {
 		log.Printf("Error parsing config files: %v", err)
 		return