Type Coercion

What’s The Issue?

The validator is mutating request body payloads.

We think we’d like to be able to configure the validator to do validation only.

Where?

See here: specifically, coerceTypes: true

    const aoav = new middlewares.RequestValidator(this.context.apiDoc, {
      coerceTypes: true,
      removeAdditional: true,
      useDefaults: true,
    });

With coerceTypes: true — the hardcoded value — we see a property being sent in the request body being transformed from the boolean literal true to the string literal "true".

"majorReferenceWork": true . // before validation

"majorReferenceWork": "true" // after validation

When I change the module so that coerceTypes: false then the boolean property remains a boolean literal. This is our desired behaviour.

How To Reproduce?

I can, and will, add a reproducible test case… but I wanted to have a quick discussion about this behaviour before doing that because you might tell me I’m doing something dumb 😄

Fix?

I don’t think the current behaviour is wrong and coerceTypes defaulting to true is fine: but, it’d be nice if we could turn this off via a configuration parameter.

Totally open to other suggestions.

[cdimascio]

@richdouglasevans i put together a test to try out your case. as far as i can tell it works correctly

Given the following spec for Pet (which is used in the POST request below)

    NewPet:
      required:
        - name
      properties:
        name:
          type: string
        tag:
          type: string
        is_cat:
          type: boolean

I created the following test (note that is_cat is specified as a boolean in the spec above, however, it is passed in the request as a string and is thus is a candidate for type coercion)

     it.only('should coerce the string 'true' to the boolean true', async () =>
        request(app)
          .post(`${basePath}/pets`)
          .send({
            name: 'test',
            is_cat: 'true', 
          })
          .expect(200)
          .then(r => {
           // return the request body after validation
            expect(r.body.is_cat).to.be.a('boolean');
          }));

The test case works as expected, the string "is_cat": true is properly coerced to boolean which i echo back in the response

Next, I created a similar test but passed a boolean in the request. Here, I want to ensure that the boolean true remain a boolean after validation. Th

     it.only('should keep the boolean true as a boolean', async () =>
        request(app)
          .post(`${basePath}/pets`)
          .send({
            name: 'test',
            is_cat: true, 
          })
          .expect(200)
          .then(r => {
            expect(r.body.is_cat).to.be.a('boolean');
          }));

This test also looks good

All in all, it’s very possible that my tests don’t match your use case. If so, please let me know. An example is of course appreciated.

On another note. as a sanity check, it may be worth verifying that type for majorReferenceWork is defined with type boolean and not string

[cdimascio]

Thanks @richdouglasevans. I’ll have a look at providing an option coerceTypes.