Express Validator - How to handle conditional Validation

Question

I have a form where if a person's shipping address is different from their Billing address they will select a radio button saying "no".

I need to be able to check what the value of this is, and if it is "no" check the form that unfolds. if it is "yes" I skip on to the next validations below. The "yes section is working, but the "no" section always returns invalidated. is there a way to nest validations in a conditional like this with this library?

Here is a screenshot of the form:

Here is the validation code i have for this scenario:

    router.post('/testData2/', [
      body('billingSameAsShipping', "Please Fill All Fields Of Your Billing Address").custom((value) => {
        if (value === 'no') {
          [
            body('billingFirstName', "Please Enter Your First Name").isLength({
              min: 1
            }),
            body('billingLastName', "Please Enter Your Last Name").isLength({
              min: 1
            }),
            body('billingAddress1', "Please Enter Your Billing Address").isLength({
              min: 1
            }),
            body('billingZip', "Please Enter Your Billing ZipCode").isLength({
              min: 1
            }),
            body('billingCity', "Please Enter Your Billing City").isLength({
              min: 1
            }),
            body('billingState', "Please Enter Your Billing State").isLength({
              min: 1
            })
          ]
        } else {

          return Promise.resolve();
        }

      }),
    body('creditCardNumber', 'Please Enter A Vaild Credit Card Number').isCreditCard(),
    body('expmonth', 'Exp Month Empty').isLength({
      min: 1
    }),
    body('expyear', 'Exp Year Empty').isLength({
      min: 1
    }),
    body('CVV', 'CVV Empty').isLength({
      min: 3
    })
  ],
  (req, res) => {...

Here is the request object we are checking against

{
  billingSameAsShipping: 'no',
  billingFirstName: 'First',
  billingLastName: 'Last',
  billingAddress1: '450 Test Ave',
  billingZip: '12345',
  billingCity: 'San Diego',
  billingState: 'CA',
}

Timothy Griffith · Accepted Answer · 2018-10-05 18:05:13Z

14

I got it, Express Validator has a conditional check built-in

I used oneOf([]) to check if the value of the radio buttons was "yes" or check that the billing address fields were filled in.

router.post('/testData2/', [
    oneOf([
      [
        body('billingFirstName', "Please Enter Your First Name").isLength({
          min: 1
        }),
        body('billingLastName', "Please Enter Your Last Name").isLength({
          min: 1
        }),
        body('billingAddress1', "Please Enter Your Billing Address").isLength({
          min: 1
        }),
        body('billingZip', "Please Enter Your Billing ZipCode").isLength({
          min: 1
        }),
        body('billingCity', "Please Enter Your Billing City").isLength({
          min: 1
        }),
        body('billingState', "Please Enter Your Billing State").isLength({
          min: 1
        })
      ],
      body('billingSameAsShipping').equals('yes')
    ], "Please Fill Out All Fields Of Your Billing Address"),
    body('creditCardNumber', 'Please Enter A Vaild Credit Card Number').isCreditCard(),
    body('expmonth', 'Exp Month Empty').isLength({
      min: 1
    }),
    body('expyear', 'Exp Year Empty').isLength({
      min: 1
    }),
    body('CVV', 'CVV Empty').isLength({
      min: 3
    })
  ],
  (req, res) => {...

That seems to be working correctly now.

Anyone have any other solutions to this one, or see anything wrong with my solution above?

answered Oct 5, 2018 at 18:05

Timothy Griffith

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3 Comments

Dorin Over a year ago

i'm using custom validators which helps me to easier parse the errors on client side

body("billingFirstName") .custom((value, { req }) => { return req.body.billingSameAsShipping === 'yes' ? true : value }) .isLength({ min: 1 }) .withMessage("Please Enter Your First Name")

Marco Over a year ago

Hi Timothy, I hope you still around as I need help with oneO(), Your answer allowed me to check for the condition but I get an error that node_modules\express-validator\src\middlewares\check.js:19 next(e); In my endpoint I check the results like so : const ValidationResults = validationResult(req) console.log(" error :", ValidationResults.array())

Marco Over a year ago

error : [ { msg: Promise { <pending> }, param: '_error', nestedErrors: [ [Object], [Object] ] } ] I see that the promise is pending but I don't know how to fix that? How did you handle the promise in the endpoint?

serguitus · Accepted Answer · 2021-09-09 16:02:29Z

7

You can also use this conditional which allows to do stuff like:

body('billingFirstName').if(body('billingSameAsShipping').equals('yes')).notEmpty(),

and the sort

answered Sep 9, 2021 at 16:02

serguitus

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Comments

Tamás Polgár · Accepted Answer · 2021-08-22 02:31:41Z

1

There is an easier way to turn validators conditional. The condition is a boolean, so you can simply use the && logical operator to decide whether to add a validator to the array or not.

router.post('/testData2/', [

   req.body.billingSameAsShipping && body('billingFirstName')
      .isLength({ min: 1 }),

   req.body.billingSameAsShipping && body('billingLastName')
      .isLength({ min: 1 })

   ].filter(x => !!x)
)

The filter at the end is needed because if the condition evaluates to false, it will add false to the array. That would cause a runtime error, so it has to be removed. This is the most concise way to add validators conditionally.

edited Aug 22, 2021 at 2:31

answered Aug 22, 2021 at 2:11

Tamás Polgár

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2 Comments

Ankur Thakur Over a year ago

This seems to be incorrect. I wonder how you are getting the context of req object for comparisons when its not a Middleware at all.

alex Over a year ago

i wonder if inversing (puting a true in the array) would also need filtering. like [!req.body.billingSameAsShipping || body('billingFirstName').isLength({min: 1}), ...]

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