Use a Function to generate validators for each field

[JwngmaBasumatary]

Hello, So I am working in a large project and I'm tired of writing the same validator code everytime so i created a few functions which will return the validation logic when i call them and i can re-use them wherever i want.

For example, suppose this is my function :

const stringValidate = (source, text, optional) => {
  switch (source) {
    case "body":
      if (optional) {
        return body(text)
          .optional()
          .isString()
          .withMessage(`${text} must be String`)
          .trim();
      }
      let val = body(text)
        .notEmpty()
        .withMessage(`${text} Required`)
        .bail()
        .isString()
        .withMessage(`${text} must be String`)
        .trim();
      console.log("val", val);
      return val;
    case "query":
      if (optional) {
        return query(text)
          .optional()
          .isString()
          .withMessage(`${text} must be String`)
          .trim();
      }
      return query(text)
        .notEmpty()
        .withMessage(`${text} Required`)
        .bail()
        .isString()
        .withMessage(`${text} must be String`)
        .trim();
    case "param":
      if (optional) {
        return param(text)
          .optional()
          .isString()
          .withMessage(`${text} must be String`)
          .trim();
      }
      return param(text)
        .notEmpty()
        .withMessage(`${text} Required`)
        .bail()
        .isString()
        .withMessage(`${text} must be String`)
        .trim();
    default:
      console.log(`Default validator case for ${text} in ${source}`);
  }
};

This function will return a validation logic for any string based validation. The function takes 3 arguments :

1. Source : source is either body, query or param
2. Text : The name of the field
3. Optional : Boolean, true if field is optional and vice-versa.

And this function I am trying to use in a route call like this

router.post(
  "",
  [
    stringValidate("body", "name", false),
  ],
  //   primaryAdminCheck,
  createAdmin
);

But the above code gives me an error

InternalServerError: argument #3 unsupported type boolean

So My question is if its possible what I am trying to do? Or do i have to look for a different method

[gustavohenke]

Hi,
I'm not sure where your message is originating from. Most likely not from express-validator. Can you create a small reproduction repository?

On another note, you can make use of buildCheckFunction to make your function way smaller.

const stringValidate = (source, text, optional) => {
  const validateFn = buildCheckFunction([source]);
  const chain = validateFn(text);
  if (optional) {
    chain.optional();
  } else {
    chain.notEmpty().withMessage(`${text} required`).bail();
  }
  return chain
    .isString()
    .withMessage(`${text} must be String`)
    .trim();
};