🤗 [Question]: How do we get multiple values for a key in form submission?

[ngocchien]

Question Description

I have a field in my form, its name is the description

Example:

<input name="item" value="item1">
<input name="description" value="description1, this is a description for item one, the first item is very nice, bla bla bla">
<input name="item" value="item2">
<input name="description" value="description2">
<input name="item" value="item3">
<input name="description" value="description3">

On my server side, I define a struct with the information:

FormCreate struct {
		Item    []string                   `json:"item" form:"item"`
		Description  []string         `json:"description" form:"description"`
	}
formData = new(FormCreate)
c.Bind().Body(formData)

I have a problem with binding data from the form to my formData.
My expectation data for formData.Description is []string{"description, this is a description for item one, the first item is very nice, bla bla bla", "description2", "description3"} (This has 3 values for the slice).
But currently, I received for formData.Description after binding data is []string{"description1", "this is a description for item one", "the first item is very nice", "bla bla bla", "description2", "description3"} (This has 6 values for the slice).

It seems that the Bind() function has split the value of the description field of the first item into a slice by the "," , so I received the data for formData.Description is []string{"description1", "this is a description for item one", "the first item is very nice", "bla bla bla", "description2", "description3"}.

Who can resolve my problem?
Thank you so much!

Code Snippet (optional)

package main

import "github.com/gofiber/fiber/v3"
import "log"

func main() {
  app := fiber.New()

  // An example to describe the question
  app.Post("/create-post", handleCreate) 
  log.Fatal(app.Listen(":3000"))
}

function handleCreate(c fiber.Ctx) error{
   FormCreate struct {
		Item    []string                   `json:"item" form:"item"`
		Description  []string         `json:"description" form:"description"`
	}
  var (
    formData = new(FormCreate)
  )
   if c.Method() == http.MethodPost {
	err = c.Bind().Body(formData)
   }
   
   return c.Render("index", fiber.Map{
        "formData": formData,
    })
}

Checklist:

• I agree to follow Fiber's Code of Conduct.
• I have checked for existing issues that describe my questions prior to opening this one.
• I understand that improperly formatted questions may be closed without explanation.

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[michal-laskowski]

@gaby

Look at this regarding to #3203

[michal-laskowski]

For JSON it will work

JSON test

// go test -v -run=^$ -bench=Test_Bind_Body_JSON_WithArray
func Test_Bind_Body_JSON_WithArray(b *testing.T) {
	var err error

	app := New()
	c := app.AcquireCtx(&fasthttp.RequestCtx{})

	type Demo struct {
		Item        []string `json:"item" form:"item"`
		Description []string `json:"description" form:"description"`
	}
	body := []byte(`{"item":["item1","item2","item3" ], "description":["description1, with coma.","description2","description3" ] }`)
	c.Request().SetBody(body)
	c.Request().Header.SetContentType(MIMEApplicationJSON)
	c.Request().Header.SetContentLength(len(body))
	d := new(Demo)

	err = c.Bind().Body(d)
	require.NoError(b, err)
	require.Equal(b, []string{"item1", "item2", "item3"}, d.Item)
	require.Equal(b, []string{"description1, with coma.", "description2", "description3"}, d.Description)
}

For forms it will not work if you allow comma (,) in value.

Form test

// go test -v -run=^$ -bench=Test_Bind_Body_Form_WithArray
func Test_Bind_Body_Form_WithArray(b *testing.T) {
	var err error

	app := New()
	c := app.AcquireCtx(&fasthttp.RequestCtx{})
	type Demo struct {
		Item        []string `json:"item" form:"item"`
		Description []string `json:"description" form:"description"`
	}

	body := []byte("item=item1&item=item2&item=item3&description=description1%2C%20with coma.&description=description2&description=description3&q=%2C")
	c.Request().SetBody(body)
	c.Request().Header.SetContentType(MIMEApplicationForm)
	c.Request().Header.SetContentLength(len(body))
	d := new(Demo)

	err = c.Bind().Body(d)

	require.NoError(b, err)
	require.Equal(b, []string{"item1", "item2", "item3"}, d.Item)
	require.Equal(b, []string{"description1, with coma.", "description2", "description3"}, d.Description)
}

[efectn]

It seems like EnableSplittingOnParsers has lost its functionality during the migration of the codebase from v2 to v3. We have to add app.config.EnableSplittingOnParsers condition again.

v2:

if c.app.config.EnableSplittingOnParsers && strings.Contains(v, ",") && equalFieldType(out, reflect.Slice, k, bodyTag) {
	values := strings.Split(v, ",")
	for i := 0; i < len(values); i++ {
		data[k] = append(data[k], values[i])
	}
} else {
	data[k] = append(data[k], v)
}

v3:

if strings.Contains(v, ",") && equalFieldType(out, reflect.Slice, k) {
	values := strings.Split(v, ",")
	for i := 0; i < len(values); i++ {
		data[k] = append(data[k], values[i])
	}
} else {
	data[k] = append(data[k], v)
}

Will work on the fix. Thanks for the bug report.