Breaking Change on v4.12.0 When Binding to map[string]interface{} -> the field become list #2652

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1. nicandcranny

   changed the title [-]Breaking Change on v4.12.0 When Binding to map[string]interface{}[/-] [+]Breaking Change on v4.12.0 When Binding to map[string]interface{} -> the field become list[/+] on Jun 27, 2024
2. thesaltree commented on Jul 9, 2024

   

   thesaltree

   on Jul 9, 2024

   Contributor

   More actions

   @slzhffktm I've submitted a pull request (#2656) that addresses this issue by maintaining backwards compatibility for map[string]interface{} binding while supporting the new functionality.

   The PR modifies the bindData function to:

   • Store single values as strings
   • Store multiple values as []string

   However, if the maintainers decide not to merge this change, here's an alternative solution you can use in your code to achieve the same result:

   func ConvertToSingleValues(input map[string]interface{}) map[string]interface{} {
       for key, value := range input {
           if strSlice, ok := value.([]string); ok {
               if len(strSlice) == 1 {
                   input[key] = strSlice[0]
               }
           }
       }
       return input
   }
   
   func ExampleFunction(c echo.Context) error {
       request := make(map[string]interface{})
       if err := c.Bind(&request); err != nil {
           return err
       }
       request := ConvertToSingleValues(request)
       return c.JSON(http.StatusOK, request)
   }

   You can use this helper function with new version without breaking code regardless of whether the PR is merged. It processes the map[string]interface{} returned by c.Bind() and converts any []string values to single strings if they contain only one element.

   👍React with 👍2Reacted by Nicholas Wijaya and Alex
3. nicandcranny commented on Sep 9, 2024

   

   nicandcranny

   on Sep 9, 2024

   Author

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   Hello @thesaltree ! Seems like your PR is merged, thank you for your contribution!!
4. nicandcranny

   closed this as completedon Sep 9, 2024
5. arigon commented on Nov 7, 2024

   

   arigon

   on Nov 7, 2024

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   However, if the maintainers decide not to merge this change, here's an alternative solution you can use in your code to achieve the same result:

   func ConvertToSingleValues(input map[string]interface{}) map[string]interface{} {
       for key, value := range input {
           if strSlice, ok := value.([]string); ok {
               if len(strSlice) == 1 {
                   input[key] = strSlice[0]
               }
           }
       }
       return input
   }

   Your return header is not necessary because map types are reference types:

   func ConvertToSingleValues(input map[string]interface{}) {
   	for key, value := range input {
   		if strSlice, ok := value.([]string); ok {
   			if len(strSlice) == 1 {
   				input[key] = strSlice[0]
   			}
   		}
   	}
   }

   I stumbled over this issue because I have the same problem after updating to 4.12.
   I'm wondering when this fix will be released, so until now I'm relying on this helper function.