Run a oneOf validation imperatively? - express

Question

I'm trying to validate a PATCH request payload for a Todo App that should have at least a text or a value property. I'm doing so in updateTodoValidators. Both properties are optional but at least one must exist (hence the oneOf) and if any exists it must be valid as the validators outside the oneOf indicate.
const validate = (validations) => {
return async (req, res, next) => {
await Promise.all(validations.map(validation => validation.run(req)));
const errors = validationResult(req)
if (errors.isEmpty()) {
return next();
}
res
.status(422)
.json({
payload: {
errors: errors.array()
},
message: "Validation error/s",
error: true
})
}
}
const updateTodoValidators = [
oneOf([
body('text').exists().withMessage('not specified'),
body('value').exists().withMessage('not specified')
]),
body('text').optional().trim().notEmpty().withMessage('cannot be empty'),
body('value').optional().isInt({ min: 1 }).withMessage('must be a valid positive number')
]
app.patch('/todos/:id', validate(updateTodoValidators), async (req, res, next) => { /* Route handler implementation */ })
I was looking into running the validations imperatively as indicated in Running validations imperatively [docs] for code readability purposes. And I discovered that if I have some validations that involve a oneOf my validate() throws with a TypeError saying validation.run is not a function. Bellow is a stack trace detailing the error:
(node:88997) UnhandledPromiseRejectionWarning: TypeError: validation.run is not a function
at Promise.all.validations.map.validation (/Users/alejandro/code/Production/server/validators/validate.js:6:64)
at Array.map (<anonymous>)
at /Users/alejandro/code/Production/server/validators/validate.js:6:35
at Layer.handle [as handle_request] (/Users/alejandro/code/Production/server/node_modules/express/lib/router/layer.js:95:5)
at next (/Users/alejandro/code/Production/server/node_modules/express/lib/router/route.js:137:13)
at loginRequired (/Users/alejandro/code/Production/server/auth/helpers.js:18:24)
at Layer.handle [as handle_request] (/Users/alejandro/code/Production/server/node_modules/express/lib/router/layer.js:95:5)
at next (/Users/alejandro/code/Production/server/node_modules/express/lib/router/route.js:137:13)
at Route.dispatch (/Users/alejandro/code/Production/server/node_modules/express/lib/router/route.js:112:3)
at Layer.handle [as handle_request] (/Users/alejandro/code/Production/server/node_modules/express/lib/router/layer.js:95:5)
(node:88997) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:88997) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
So, my question is: Is there any way to run validations imperatively when validations might involve one or more oneOfs?

Answer 1

I ended up doing it manually.
Do a .run() on both param checks. Then validate the _errors property is empty on both.
export const validateTokens = async (req, res, next) => {
// Check to make sure one of the header tokens is set and a UUID
const token1 = await header('token1')
.isUUID()
.run(req);
const token2 = await header('token2')
.isUUID()
.run(req);
// Manual oneOf
if (isEmpty(token1._errors) || isEmpty(token2._errors)) {
return next();
}
// Return error results
res.status(400).send('Must include either token1 or token2');
};

Answer 2

oneOf returns a middleware instance, not a validation chain. It doesn't have a .run() function which your customer middleware validator uses to validate hence it is erroring out.
There is an open issue for this here
For the moment I think you would need to implement you own custom function to validate these conditional parameters.