up: update some error define, update the binding struct logic

export.go

@@ -56,7 +56,7 @@ func MapOnExists(key string, dst interface{}) error {
 // MapOnExists mapping data to the dst structure only on key exists.
 func (c *Config) MapOnExists(key string, dst interface{}) error {
 	err := c.Structure(key, dst)
-	if err != nil && err == errNotFound {
+	if err != nil && err == ErrNotFound {
 		return nil
 	}
 
@@ -71,36 +71,21 @@ func (c *Config) MapOnExists(key string, dst interface{}) error {
 //	config.Structure("db", &dbInfo)
 func (c *Config) Structure(key string, dst interface{}) error {
 	var data interface{}
-	if key == "" { // binding all data
+	// binding all data
+	if key == "" {
 		data = c.data
-	} else { // some data of the config
+	} else {
+		// binding sub-data of the config
 		var ok bool
 		data, ok = c.GetValue(key)
 		if !ok {
-			return errNotFound
-		}
-	}
-
-	var bindConf *mapstructure.DecoderConfig
-	if c.opts.DecoderConfig == nil {
-		bindConf = newDefaultDecoderConfig(c.opts.TagName)
-	} else {
-		// copy new config for each binding.
-		copyConf := *c.opts.DecoderConfig
-		bindConf = &copyConf
-
-		// compatible with previous settings opts.TagName
-		if bindConf.TagName == "" {
-			bindConf.TagName = c.opts.TagName
+			return ErrNotFound
 		}
 	}
 
-	// add hook on decode value to struct
-	if bindConf.DecodeHook == nil && c.opts.shouldAddHookFunc() {
-		bindConf.DecodeHook = ValDecodeHookFunc(c.opts.ParseEnv, c.opts.ParseTime)
-	}
-
-	bindConf.Result = dst // set result struct ptr
+	bindConf := c.opts.makeDecoderConfig()
+	// set result struct ptr
+	bindConf.Result = dst
 	decoder, err := mapstructure.NewDecoder(bindConf)
 
 	if err == nil {

options.go

@@ -42,8 +42,10 @@ type Options struct {
 	ReadFormat string
 	// DecoderConfig setting for binding data to struct. such as: TagName
 	DecoderConfig *mapstructure.DecoderConfig
-	// HookFunc on data changed.
+	// HookFunc on data changed. you can do something...
 	HookFunc HookFunc
+	// ParseDefault tag on binding data to struct. tag: default
+	ParseDefault bool
 	// WatchChange bool
 }
 
@@ -77,6 +79,29 @@ func (o *Options) shouldAddHookFunc() bool {
 	return o.ParseTime || o.ParseEnv
 }
 
+func (o *Options) makeDecoderConfig() *mapstructure.DecoderConfig {
+	var bindConf *mapstructure.DecoderConfig
+	if o.DecoderConfig == nil {
+		bindConf = newDefaultDecoderConfig(o.TagName)
+	} else {
+		// copy new config for each binding.
+		copyConf := *o.DecoderConfig
+		bindConf = &copyConf
+
+		// compatible with previous settings opts.TagName
+		if bindConf.TagName == "" {
+			bindConf.TagName = o.TagName
+		}
+	}
+
+	// add hook on decode value to struct
+	if bindConf.DecodeHook == nil && o.shouldAddHookFunc() {
+		bindConf.DecodeHook = ValDecodeHookFunc(o.ParseEnv, o.ParseTime)
+	}
+
+	return bindConf
+}
+
 /*************************************************************
  * config setting
  *************************************************************/
@@ -87,6 +112,9 @@ func ParseEnv(opts *Options) { opts.ParseEnv = true }
 // ParseTime set parse time string.
 func ParseTime(opts *Options) { opts.ParseTime = true }
 
+// ParseDefault tag value on binding data to struct.
+func ParseDefault(opts *Options) { opts.ParseDefault = true }
+
 // Readonly set readonly
 func Readonly(opts *Options) { opts.Readonly = true }
 

read.go

@@ -1,7 +1,6 @@
 package config
 
 import (
-	"errors"
 	"strconv"
 	"strings"
 
@@ -10,11 +9,6 @@ import (
 	"github.com/gookit/goutil/strutil"
 )
 
-var (
-	errInvalidKey = errors.New("invalid config key string")
-	errNotFound   = errors.New("this key does not exist in the config")
-)
-
 // Exists key exists check
 func Exists(key string, findByPath ...bool) bool { return dc.Exists(key, findByPath...) }
 
@@ -122,7 +116,7 @@ func GetValue(key string, findByPath ...bool) (interface{}, bool) {
 func (c *Config) GetValue(key string, findByPath ...bool) (value interface{}, ok bool) {
 	sep := c.opts.Delimiter
 	if key = formatKey(key, string(sep)); key == "" {
-		c.addError(errInvalidKey)
+		c.addError(ErrKeyIsEmpty)
 		return
 	}
 
@@ -139,13 +133,13 @@ func (c *Config) GetValue(key string, findByPath ...bool) (value interface{}, ok
 
 	// disable find by path.
 	if len(findByPath) > 0 && !findByPath[0] {
-		// c.addError(errNotFound)
+		// c.addError(ErrNotFound)
 		return
 	}
 
 	// has sub key? eg. "lang.dir"
 	if strings.IndexByte(key, sep) == -1 {
-		// c.addError(errNotFound)
+		// c.addError(ErrNotFound)
 		return
 	}
 
@@ -155,7 +149,7 @@ func (c *Config) GetValue(key string, findByPath ...bool) (value interface{}, ok
 	// find top item data based on top key
 	var item interface{}
 	if item, ok = c.data[topK]; !ok {
-		// c.addError(errNotFound)
+		// c.addError(ErrNotFound)
 		return
 	}
 

write.go

@@ -7,10 +7,11 @@ import (
 	"github.com/gookit/goutil/maputil"
 )
 
-// some common errors on set value
+// some common errors definitions
 var (
 	ErrReadonly   = errors.New("the config instance in 'readonly' mode")
 	ErrKeyIsEmpty = errors.New("the config key is cannot be empty")
+	ErrNotFound   = errors.New("this key does not exist in the config")
 )
 
 // SetData for override the Config.Data