Response Customization

The httpform package provides configurable response options for APIs that require standardized validation responses across frontend applications, backend services, or distributed systems.

Response customization is handled through:

httpform.ResponseOptions

This allows validation handlers to control:

• validation messages
• invalid JSON messages
• response formatting
• unique validation error codes

ResponseOptions

Example:

opts := httpform.ResponseOptions{
	ErrorFormat:        httpform.ErrorFormatMap,
	ValidationMessage:  "please check your input",
	InvalidJSONMessage: "request body is not valid JSON",
	UniqueCodes:        true,
}

Custom Validation Messages

Custom validation messages override the default top-level validation response.

Example:

ValidationMessage: "please check your input"

Response example:

{
  "message": "please check your input",
  "errors": {
    "email": [
      {
        "code": "email_invalid",
        "message": "must be a valid email"
      }
    ]
  }
}

This is useful for:

• API consistency
• frontend integrations
• localization pipelines
• standardized service responses

Invalid JSON Messages

The InvalidJSONMessage option customizes malformed JSON responses.

Example:

InvalidJSONMessage: "request body is not valid JSON"

This separates:

• parsing errors
• validation errors
• successful requests

while keeping response contracts consistent.

Unique Error Codes

Validation rules may generate duplicate error codes for a single field.

Example:

UniqueCodes: true

When enabled, duplicate validation codes are automatically removed from the response.

This is useful for:

• frontend validation rendering
• API response normalization
• validation aggregation
• simplified error handling

Complete Example

opts := httpform.ResponseOptions{
	ErrorFormat:        httpform.ErrorFormatMap,
	ValidationMessage:  "please check your input",
	InvalidJSONMessage: "request body is not valid JSON",
	UniqueCodes:        true,
}

if !httpform.BindAndValidateWithOptions(
	w,
	req,
	&in,
	ResponseExampleSchema(),
	1<<20,
	opts,
) {
	return
}

Response customization allows APIs to standardize validation behavior while keeping validation schemas reusable and transport-independent.

Notes

• ResponseOptions only affects HTTP response formatting and does not modify schema validation behavior.
• Validation schemas remain reusable independently of HTTP transport and response serialization.
• UniqueCodes removes duplicated validation codes per field but preserves the original validation execution order.
• BindAndValidateWithOptions is typically used in APIs that require consistent response contracts across multiple services or frontend applications.
• Validation helpers automatically write the HTTP response and should generally return immediately after validation failure.
• Response customization is transport-level behavior and should remain separate from business validation logic whenever possible.