context:add Bind function

// Bind data from request.Form[key] to dest
// like
/?id=123&isok=true&ft=1.2&ol[0]=1&ol[1]=2&ul[]=str&ul[]=array&user.Name=
astaxie
// var id int  beegoInput.Bind(&id, "id")  id ==123
// var isok bool  beegoInput.Bind(&isok, "isok")  id ==true
// var ft float64  beegoInput.Bind(&ft, "ft")  ft ==1.2
// ol := make([]int, 0, 2)  beegoInput.Bind(&ol, "ol")  ol ==[1 2]
// ul := make([]string, 0, 2)  beegoInput.Bind(&ul, "ul")  ul ==[str
array]
// user struct{Name}  beegoInput.Bind(&user, "user")  user ==
{Name:"astaxie"}

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"errors"
 	"io/ioutil"
 	"io/ioutil"
 	"net/http"
 	"net/http"
+	"net/url"
 	"reflect"
 	"reflect"
 	"strconv"
 	"strconv"
 	"strings"
 	"strings"
@@ -276,3 +277,244 @@ func (input *BeegoInput) ParseFormOrMulitForm(maxMemory int64) error {
 	}
 	}
 	return nil
 	return nil
 }
 }
+
+// Bind data from request.Form[key] to dest
+// like /?id=123&isok=true&ft=1.2&ol[0]=1&ol[1]=2&ul[]=str&ul[]=array&user.Name=astaxie
+// var id int  beegoInput.Bind(&id, "id")  id ==123
+// var isok bool  beegoInput.Bind(&isok, "isok")  id ==true
+// var ft float64  beegoInput.Bind(&ft, "ft")  ft ==1.2
+// ol := make([]int, 0, 2)  beegoInput.Bind(&ol, "ol")  ol ==[1 2]
+// ul := make([]string, 0, 2)  beegoInput.Bind(&ul, "ul")  ul ==[str array]
+// user struct{Name}  beegoInput.Bind(&user, "user")  user == {Name:"astaxie"}
+func (input *BeegoInput) Bind(dest interface{}, key string) error {
+	value := reflect.ValueOf(dest)
+	if value.Kind() != reflect.Ptr {
+		return errors.New("beego: non-pointer passed to Bind: " + key)
+	}
+	value = value.Elem()
+	if !value.CanSet() {
+		return errors.New("beego: non-settable variable passed to Bind: " + key)
+	}
+	rv := input.bind(key, value.Type())
+	if !rv.IsValid() {
+		return errors.New("beego: reflect value is empty")
+	}
+	value.Set(rv)
+	return nil
+}
+
+func (input *BeegoInput) bind(key string, typ reflect.Type) reflect.Value {
+	rv := reflect.Zero(reflect.TypeOf(0))
+	switch typ.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		val := input.Query(key)
+		if len(val) == 0 {
+			return rv
+		}
+		rv = input.bindInt(val, typ)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		val := input.Query(key)
+		if len(val) == 0 {
+			return rv
+		}
+		rv = input.bindUint(val, typ)
+	case reflect.Float32, reflect.Float64:
+		val := input.Query(key)
+		if len(val) == 0 {
+			return rv
+		}
+		rv = input.bindFloat(val, typ)
+	case reflect.String:
+		val := input.Query(key)
+		if len(val) == 0 {
+			return rv
+		}
+		rv = input.bindString(val, typ)
+	case reflect.Bool:
+		val := input.Query(key)
+		if len(val) == 0 {
+			return rv
+		}
+		rv = input.bindBool(val, typ)
+	case reflect.Slice:
+		rv = input.bindSlice(&input.Request.Form, key, typ)
+	case reflect.Struct:
+		rv = input.bindStruct(&input.Request.Form, key, typ)
+	case reflect.Ptr:
+		rv = input.bindPoint(key, typ)
+	case reflect.Map:
+		rv = input.bindMap(&input.Request.Form, key, typ)
+	}
+	return rv
+}
+
+func (input *BeegoInput) bindValue(val string, typ reflect.Type) reflect.Value {
+	rv := reflect.Zero(reflect.TypeOf(0))
+	switch typ.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		rv = input.bindInt(val, typ)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		rv = input.bindUint(val, typ)
+	case reflect.Float32, reflect.Float64:
+		rv = input.bindFloat(val, typ)
+	case reflect.String:
+		rv = input.bindString(val, typ)
+	case reflect.Bool:
+		rv = input.bindBool(val, typ)
+	case reflect.Slice:
+		rv = input.bindSlice(&url.Values{"": {val}}, "", typ)
+	case reflect.Struct:
+		rv = input.bindStruct(&url.Values{"": {val}}, "", typ)
+	case reflect.Ptr:
+		rv = input.bindPoint(val, typ)
+	case reflect.Map:
+		rv = input.bindMap(&url.Values{"": {val}}, "", typ)
+	}
+	return rv
+}
+
+func (input *BeegoInput) bindInt(val string, typ reflect.Type) reflect.Value {
+	intValue, err := strconv.ParseInt(val, 10, 64)
+	if err != nil {
+		return reflect.Zero(typ)
+	}
+	pValue := reflect.New(typ)
+	pValue.Elem().SetInt(intValue)
+	return pValue.Elem()
+}
+
+func (input *BeegoInput) bindUint(val string, typ reflect.Type) reflect.Value {
+	uintValue, err := strconv.ParseUint(val, 10, 64)
+	if err != nil {
+		return reflect.Zero(typ)
+	}
+	pValue := reflect.New(typ)
+	pValue.Elem().SetUint(uintValue)
+	return pValue.Elem()
+}
+
+func (input *BeegoInput) bindFloat(val string, typ reflect.Type) reflect.Value {
+	floatValue, err := strconv.ParseFloat(val, 64)
+	if err != nil {
+		return reflect.Zero(typ)
+	}
+	pValue := reflect.New(typ)
+	pValue.Elem().SetFloat(floatValue)
+	return pValue.Elem()
+}
+
+func (input *BeegoInput) bindString(val string, typ reflect.Type) reflect.Value {
+	return reflect.ValueOf(val)
+}
+
+func (input *BeegoInput) bindBool(val string, typ reflect.Type) reflect.Value {
+	val = strings.TrimSpace(strings.ToLower(val))
+	switch val {
+	case "true", "on", "1":
+		return reflect.ValueOf(true)
+	}
+	return reflect.ValueOf(false)
+}
+
+type sliceValue struct {
+	index int           // Index extracted from brackets.  If -1, no index was provided.
+	value reflect.Value // the bound value for this slice element.
+}
+
+func (input *BeegoInput) bindSlice(params *url.Values, key string, typ reflect.Type) reflect.Value {
+	maxIndex := -1
+	numNoIndex := 0
+	sliceValues := []sliceValue{}
+	for reqKey, vals := range *params {
+		if !strings.HasPrefix(reqKey, key+"[") {
+			continue
+		}
+		// Extract the index, and the index where a sub-key starts. (e.g. field[0].subkey)
+		index := -1
+		leftBracket, rightBracket := len(key), strings.Index(reqKey[len(key):], "]")+len(key)
+		if rightBracket > leftBracket+1 {
+			index, _ = strconv.Atoi(reqKey[leftBracket+1 : rightBracket])
+		}
+		subKeyIndex := rightBracket + 1
+
+		// Handle the indexed case.
+		if index > -1 {
+			if index > maxIndex {
+				maxIndex = index
+			}
+			sliceValues = append(sliceValues, sliceValue{
+				index: index,
+				value: input.bind(reqKey[:subKeyIndex], typ.Elem()),
+			})
+			continue
+		}
+
+		// It's an un-indexed element.  (e.g. element[])
+		numNoIndex += len(vals)
+		for _, val := range vals {
+			// Unindexed values can only be direct-bound.
+			sliceValues = append(sliceValues, sliceValue{
+				index: -1,
+				value: input.bindValue(val, typ.Elem()),
+			})
+		}
+	}
+	resultArray := reflect.MakeSlice(typ, maxIndex+1, maxIndex+1+numNoIndex)
+	for _, sv := range sliceValues {
+		if sv.index != -1 {
+			resultArray.Index(sv.index).Set(sv.value)
+		} else {
+			resultArray = reflect.Append(resultArray, sv.value)
+		}
+	}
+	return resultArray
+}
+
+func (input *BeegoInput) bindStruct(params *url.Values, key string, typ reflect.Type) reflect.Value {
+	result := reflect.New(typ).Elem()
+	fieldValues := make(map[string]reflect.Value)
+	for reqKey, val := range *params {
+		if !strings.HasPrefix(reqKey, key+".") {
+			continue
+		}
+
+		fieldName := reqKey[len(key)+1:]
+
+		if _, ok := fieldValues[fieldName]; !ok {
+			// Time to bind this field.  Get it and make sure we can set it.
+			fieldValue := result.FieldByName(fieldName)
+			if !fieldValue.IsValid() {
+				continue
+			}
+			if !fieldValue.CanSet() {
+				continue
+			}
+			boundVal := input.bindValue(val[0], fieldValue.Type())
+			fieldValue.Set(boundVal)
+			fieldValues[fieldName] = boundVal
+		}
+	}
+
+	return result
+}
+
+func (input *BeegoInput) bindPoint(key string, typ reflect.Type) reflect.Value {
+	return input.bind(key, typ.Elem()).Addr()
+}
+
+func (input *BeegoInput) bindMap(params *url.Values, key string, typ reflect.Type) reflect.Value {
+	var (
+		result    = reflect.MakeMap(typ)
+		keyType   = typ.Key()
+		valueType = typ.Elem()
+	)
+	for paramName, values := range *params {
+		if !strings.HasPrefix(paramName, key+"[") || paramName[len(paramName)-1] != ']' {
+			continue
+		}
+
+		key := paramName[len(key)+1 : len(paramName)-1]
+		result.SetMapIndex(input.bindValue(key, keyType), input.bindValue(values[0], valueType))
+	}
+	return result
+}

+package context
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+)
+
+func TestParse(t *testing.T) {
+	r, _ := http.NewRequest("GET", "/?id=123&isok=true&ft=1.2&ol[0]=1&ol[1]=2&ul[]=str&ul[]=array&user.Name=astaxie", nil)
+	beegoInput := NewInput(r)
+	beegoInput.ParseFormOrMulitForm(1 << 20)
+
+	var id int
+	err := beegoInput.Bind(&id, "id")
+	if id != 123 || err != nil {
+		t.Fatal("id should has int value")
+	}
+	fmt.Println(id)
+
+	var isok bool
+	err = beegoInput.Bind(&isok, "isok")
+	if !isok || err != nil {
+		t.Fatal("isok should be true")
+	}
+	fmt.Println(isok)
+
+	var float float64
+	err = beegoInput.Bind(&float, "ft")
+	if float != 1.2 || err != nil {
+		t.Fatal("float should be equal to 1.2")
+	}
+	fmt.Println(float)
+
+	ol := make([]int, 0, 2)
+	err = beegoInput.Bind(&ol, "ol")
+	if len(ol) != 2 || err != nil || ol[0] != 1 || ol[1] != 2 {
+		t.Fatal("ol should has two elements")
+	}
+	fmt.Println(ol)
+
+	ul := make([]string, 0, 2)
+	err = beegoInput.Bind(&ul, "ul")
+	if len(ul) != 2 || err != nil || ul[0] != "str" || ul[1] != "array" {
+		t.Fatal("ul should has two elements")
+	}
+	fmt.Println(ul)
+
+	type User struct {
+		Name string
+	}
+	user := User{}
+	err = beegoInput.Bind(&user, "user")
+	if err != nil || user.Name != "astaxie" {
+		t.Fatal("user should has name")
+	}
+	fmt.Println(user)
+}