express-validator 验证数组参数

Question

I am using express-validator to validate POST data in my express application. I have a form which has a select where in user can select multiple options:

<select name="category" multiple id="category">
    <option value="1">category 1 </option>
    .......
</select>

The payload after submitting form shows me this if I select multiple values:

...&category=1&category=2&....

Now, in my Express application I try to validate it like this:

req.checkBody('category', 'category cannot be empty').notEmpty();

But, even after I send multiple values I always get the error - category cannot be empty . If I print my variable as req.body.category[0] - I get the data. But, somehow not able to understand the way I need to pass this to my validator.

Answer 1

You may need to create your own custom validator;

expressValidator = require('express-validator');
validator = require('validator');

app.use(expressValidator({
  customValidators: {
     isArray: function(value) {
        return Array.isArray(value);
     },
     notEmpty: function(array) {
        return array.length > 0;
     }
     gte: function(param, num) {
        return param >= num;
     }
  }
}));

req.checkBody('category', 'category cannot be empty').isArray().notEmpty();

Answer 2

Try this:

router.post('/your-url', 
      [
        check('category').custom((options, { req, location, path }) => {
            if (typeof category === 'object' && category && Array.isArray(category) && category.length) {
              return true;
            } else {
              return false;
            }
          })
    ],
    controller.fn);

Answer 3

Answering a bit late but hope this might help somebody.

If you are using express-validator , You can pass minimum / maximum length option to check whether Array is empty or exceeds a certain limit

req.checkBody('category', 'category cannot be empty').isArray({ min: 1, max: 10 });

Answer 4

If you are using schema, you can do it this way:

const schema = {
  someArray: { isArray: true, notEmpty: true }
};

Answer 5

This maybe a bit late but for others who wants a clean solution without using the customValidator , I created a validator that can dig up to the deepest array and validate its content.

https://github.com/edgracilla/wallter

In your case validation would be:

const halter = require('wallter').halter
const Builder = require('wallter').builder // validation schema builder

const builder = new Builder()

server.use(halter())

server.post('/test', function (req, res, next) {
    let validationSchema = builder.fresh()
      .addRule('category.*', 'required')
      .build()

    // validationSchema output:
    // { 'category.*': { required: { msg: 'Value for field \'category.*\' is required' } } }

    req.halt(validationSchema).then(result => {
        if (result.length) {
            res.send(400, result)
        } else {
            res.send(200)
        }

        return next()
    })
})

Error message can be override in builder initialization. Check the repo README.md for an in depth usage.