@FormField - add validation for submitted multipart/form-data fields

[tsimbalar]

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Expected Behavior

If I declare a @FormField('myField') in a controller method such as :

/**
 *
 * @maxLength 40
 */
type StringWIthMaxLength = string;

// ...

  public async create(
    @FormField('presentation') presentation: StringWIthMaxLength,
  ): Promise<{}> {

or inline as tsdocs

  public async create(
    /**
     *
     * @maxLength 40
     */
    @FormField('presentation') presentation: string,
  ): Promise<{}>

the generated OpenApi spec should contain information about those constraints, and those constraints should be enforced at runtime too.

I would expect something like this in the Open API yaml :

        post:
            operationId: Create
            parameters: []
            requestBody:
                required: true
                content:
                    multipart/form-data:
                        schema:
                            type: object
                            properties:
                                presentation:
                                    type: string
                                    maxLength: 40

Current Behavior

Annotation / constraints are ignored in the generated swagger file and at runtime.

        post:
            operationId: Create
            parameters: []
            requestBody:
                required: true
                content:
                    multipart/form-data:
                        schema:
                            type: object
                            properties:
                                presentation:
                                    type: string

Possible Solution

The data submitted through FormField should be documented and validated the same way as if they were a property of a submitted JSON paylog.

Steps to Reproduce

Context (Environment)

Version of the library: v3.6.1 Version of NodeJS: v14.16.0 (current LTS)

• Confirm you were using yarn not npm: [ ] - using npm here ...

Detailed Description

Breaking change?

This would be a change for people who are using tsoa v3.6.0+ and are using something other than string as the type of the argument annotated with @FormField ... but for those people I would consider that current behavior is unexpected anyway.

[alexandervandekleutab]

I'm not in the position to help implement this, but I also encountered a need for this feature today.

[WoH]

Have you tried jddoc at the method level? This is how you're supposed to annotate parameters generally speaking.

As in

/**
 * @maxLenth presentation 40
 */
public async create(
    @FormField('presentation') presentation: string,
  ): Promise<{}>