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feat(context): ShouldBind counterparts for Bind methods (#1047) 

* feat(context): ShouldBind counterparts for Bind methods + tests

* docs(readme): Switch examples to use ShouldBind methods

Add section for bind methods types, explain difference in behavior.
Switch all `c.Bind` examples to use `c.ShouldBind`.
This commit is contained in:
Suhas Karanth 2017-10-23 14:44:09 +05:30 committed by Javier Provecho Fernandez
parent b8b68314fa
commit dfb68ce085
3 changed files with 138 additions and 14 deletions
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56
README.md
View File

@ -447,9 +447,17 @@ Gin uses [**go-playground/validator.v8**](https://github.com/go-playground/valid
Note that you need to set the corresponding binding tag on all fields you want to bind. For example, when binding from JSON, set `json:"fieldname"`.
When using the Bind-method, Gin tries to infer the binder depending on the Content-Type header. If you are sure what you are binding, you can use BindWith.
Also, Gin provides two sets of methods for binding:
- **Type** - Must bind
- **Methods** - `Bind`, `BindJSON`, `BindQuery`
- **Behavior** - These methods use `MustBindWith` under the hood. If there is a binding error, the request is aborted with `c.AbortWithError(400, err).SetType(ErrorTypeBind)`. This sets the response status code to 400 and the `Content-Type` header is set to `text/plain; charset=utf-8`. Note that if you try to set the response code after this, it will result in a warning `[GIN-debug] [WARNING] Headers were already written. Wanted to override status code 400 with 422`. If you wish to have greater control over the behavior, consider using the `ShouldBind` equivalent method.
- **Type** - Should bind
- **Methods** - `ShouldBind`, `ShouldBindJSON`, `ShouldBindQuery`
- **Behavior** - These methods use `ShouldBindWith` under the hood. If there is a binding error, the error is returned and it is the developer's responsibility to handle the request and error appropriately.
You can also specify that specific fields are required. If a field is decorated with `binding:"required"` and has a empty value when binding, the current request will fail with an error.
When using the Bind-method, Gin tries to infer the binder depending on the Content-Type header. If you are sure what you are binding, you can use `MustBindWith` or `ShouldBindWith`.
You can also specify that specific fields are required. If a field is decorated with `binding:"required"` and has a empty value when binding, an error will be returned.
```go
// Binding from JSON
@ -464,12 +472,14 @@ func main() {
// Example for binding JSON ({"user": "manu", "password": "123"})
router.POST("/loginJSON", func(c *gin.Context) {
var json Login
if c.BindJSON(&json) == nil {
if err = c.ShouldBindJSON(&json); err == nil {
if json.User == "manu" && json.Password == "123" {
c.JSON(http.StatusOK, gin.H{"status": "you are logged in"})
} else {
c.JSON(http.StatusUnauthorized, gin.H{"status": "unauthorized"})
}
} else {
c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
}
})
@ -477,12 +487,14 @@ func main() {
router.POST("/loginForm", func(c *gin.Context) {
var form Login
// This will infer what binder to use depending on the content-type header.
if c.Bind(&form) == nil {
if err := c.ShouldBind(&form); err == nil {
if form.User == "manu" && form.Password == "123" {
c.JSON(http.StatusOK, gin.H{"status": "you are logged in"})
} else {
c.JSON(http.StatusUnauthorized, gin.H{"status": "unauthorized"})
}
} else {
c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
}
})
@ -491,6 +503,28 @@ func main() {
}
```
**Sample request**
```shell
$ curl -v -X POST \
http://localhost:8080/loginJSON \
-H 'content-type: application/json' \
-d '{ "user": "manu" }'
> POST /loginJSON HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.51.0
> Accept: */*
> content-type: application/json
> Content-Length: 18
>
* upload completely sent off: 18 out of 18 bytes
< HTTP/1.1 400 Bad Request
< Content-Type: application/json; charset=utf-8
< Date: Fri, 04 Aug 2017 03:51:31 GMT
< Content-Length: 100
<
{"error":"Key: 'Login.Password' Error:Field validation for 'Password' failed on the 'required' tag"}
```
### Custom Validators
It is also possible to register custom validators. See the [example code](examples/custom-validation/server.go).
@ -554,7 +588,7 @@ $ curl "localhost:8085/bookable?check_in=2017-08-15&check_out=2017-08-16"
### Only Bind Query String
`BindQuery` function only binds the query params and not the post data. See the [detail information](https://github.com/gin-gonic/gin/issues/742#issuecomment-315953017).
`ShouldBindQuery` function only binds the query params and not the post data. See the [detail information](https://github.com/gin-gonic/gin/issues/742#issuecomment-315953017).
```go
package main
@ -578,7 +612,7 @@ func main() {
func startPage(c *gin.Context) {
var person Person
if c.BindQuery(&person) == nil {
if c.ShouldBindQuery(&person) == nil {
log.Println("====== Only Bind By Query String ======")
log.Println(person.Name)
log.Println(person.Address)
@ -616,7 +650,7 @@ func startPage(c *gin.Context) {
// If `GET`, only `Form` binding engine (`query`) used.
// If `POST`, first checks the `content-type` for `JSON` or `XML`, then uses `Form` (`form-data`).
// See more at https://github.com/gin-gonic/gin/blob/master/binding/binding.go#L48
if c.Bind(&person) == nil {
if c.ShouldBind(&person) == nil {
log.Println(person.Name)
log.Println(person.Address)
log.Println(person.Birthday)
@ -648,7 +682,7 @@ type myForm struct {
func formHandler(c *gin.Context) {
var fakeForm myForm
c.Bind(&fakeForm)
c.ShouldBind(&fakeForm)
c.JSON(200, gin.H{"color": fakeForm.Colors})
}
@ -695,11 +729,11 @@ func main() {
router := gin.Default()
router.POST("/login", func(c *gin.Context) {
// you can bind multipart form with explicit binding declaration:
// c.MustBindWith(&form, binding.Form)
// or you can simply use autobinding with Bind method:
// c.ShouldBindWith(&form, binding.Form)
// or you can simply use autobinding with ShouldBind method:
var form LoginForm
// in this case proper binding will be automatically selected
if c.Bind(&form) == nil {
if c.ShouldBind(&form) == nil {
if form.User == "user" && form.Password == "password" {
c.JSON(200, gin.H{"status": "you are logged in"})
} else {

23
context.go
View File

@ -482,6 +482,29 @@ func (c *Context) MustBindWith(obj interface{}, b binding.Binding) (err error) {
return
}
// ShouldBind checks the Content-Type to select a binding engine automatically,
// Depending the "Content-Type" header different bindings are used:
// "application/json" --> JSON binding
// "application/xml" --> XML binding
// otherwise --> returns an error
// It parses the request's body as JSON if Content-Type == "application/json" using JSON or XML as a JSON input.
// It decodes the json payload into the struct specified as a pointer.
// Like c.Bind() but this method does not set the response status code to 400 and abort if the json is not valid.
func (c *Context) ShouldBind(obj interface{}) error {
b := binding.Default(c.Request.Method, c.ContentType())
return c.ShouldBindWith(obj, b)
}
// ShouldBindJSON is a shortcut for c.ShouldBindWith(obj, binding.JSON).
func (c *Context) ShouldBindJSON(obj interface{}) error {
return c.ShouldBindWith(obj, binding.JSON)
}
// ShouldBindQuery is a shortcut for c.ShouldBindWith(obj, binding.Query).
func (c *Context) ShouldBindQuery(obj interface{}) error {
return c.ShouldBindWith(obj, binding.Query)
}
// ShouldBindWith binds the passed struct pointer using the specified binding engine.
// See the binding package.
func (c *Context) ShouldBindWith(obj interface{}, b binding.Binding) error {

67
context_test.go
View File

@ -1228,6 +1228,73 @@ func TestContextBadAutoBind(t *testing.T) {
assert.True(t, c.IsAborted())
}
func TestContextAutoShouldBindJSON(t *testing.T) {
c, _ := CreateTestContext(httptest.NewRecorder())
c.Request, _ = http.NewRequest("POST", "/", bytes.NewBufferString("{\"foo\":\"bar\", \"bar\":\"foo\"}"))
c.Request.Header.Add("Content-Type", MIMEJSON)
var obj struct {
Foo string `json:"foo"`
Bar string `json:"bar"`
}
assert.NoError(t, c.ShouldBind(&obj))
assert.Equal(t, obj.Bar, "foo")
assert.Equal(t, obj.Foo, "bar")
assert.Empty(t, c.Errors)
}
func TestContextShouldBindWithJSON(t *testing.T) {
w := httptest.NewRecorder()
c, _ := CreateTestContext(w)
c.Request, _ = http.NewRequest("POST", "/", bytes.NewBufferString("{\"foo\":\"bar\", \"bar\":\"foo\"}"))
c.Request.Header.Add("Content-Type", MIMEXML) // set fake content-type
var obj struct {
Foo string `json:"foo"`
Bar string `json:"bar"`
}
assert.NoError(t, c.ShouldBindJSON(&obj))
assert.Equal(t, obj.Bar, "foo")
assert.Equal(t, obj.Foo, "bar")
assert.Equal(t, w.Body.Len(), 0)
}
func TestContextShouldBindWithQuery(t *testing.T) {
w := httptest.NewRecorder()
c, _ := CreateTestContext(w)
c.Request, _ = http.NewRequest("POST", "/?foo=bar&bar=foo", bytes.NewBufferString("foo=unused"))
var obj struct {
Foo string `form:"foo"`
Bar string `form:"bar"`
}
assert.NoError(t, c.ShouldBindQuery(&obj))
assert.Equal(t, "foo", obj.Bar)
assert.Equal(t, "bar", obj.Foo)
assert.Equal(t, 0, w.Body.Len())
}
func TestContextBadAutoShouldBind(t *testing.T) {
w := httptest.NewRecorder()
c, _ := CreateTestContext(w)
c.Request, _ = http.NewRequest("POST", "http://example.com", bytes.NewBufferString("\"foo\":\"bar\", \"bar\":\"foo\"}"))
c.Request.Header.Add("Content-Type", MIMEJSON)
var obj struct {
Foo string `json:"foo"`
Bar string `json:"bar"`
}
assert.False(t, c.IsAborted())
assert.Error(t, c.ShouldBind(&obj))
assert.Empty(t, obj.Bar)
assert.Empty(t, obj.Foo)
assert.False(t, c.IsAborted())
}
func TestContextGolangContext(t *testing.T) {
c, _ := CreateTestContext(httptest.NewRecorder())
c.Request, _ = http.NewRequest("POST", "/", bytes.NewBufferString("{\"foo\":\"bar\", \"bar\":\"foo\"}"))