Validation Quickstart

To learn more about Simple Body Validator's validation feature, let's look at a complete example of validating a data object and displaying the error messages back to the user.

By reading the following examples, you will be able to gain a good understanding of the main validation features.

Create a new validation instance

To create a new validation instance you need to import the make method.

    import { make } from 'simple-body-validator';

    const { make } = require('simple-body-validator');

The first argument passed to the make method is the data under validation. The second argument is an object of the validation rules that should be applied to the data.

    const data = {
        name: 'John',
        email: 'John@gmail.com',
        age: 28
    };

    const rules = {
        name: 'required|string|min:3',
        email: 'required|email',
        age: 'min:18'
    };

    const validator = make(data, rules);

As you can see the validation rules are passed as the second argument to the make method. All available validation rules are documented here.

Alternatively, validation rules may be specified as arrays of rules instead of a single | delimited string.

    const rules = {
        name: ['required', 'string', 'min:3'],
        email: ['required', 'email'],
        age: ['min:18']
    };

If you want a more expressive way to set your data and rules, you can chain the methods as shown below.

    const validator = make().setData(data).setRules(rules);

Run Validation

To run the validation against the defined rules you need to invoke the validate method, which will return false in case of failure and true in case of success.

In case of validation failure, an error object will be returned based on the failed rules. You can find out more about validation errors

    if (! validator.validate()) {
        console.log('Errors: ', validator.errors().all());
    }

Stopping On First Validation Failure

The stopOnFirstFailure method will inform the validator that it should stop validating all attributes once a single validation failure has occurred

    if (! validator.stopOnFirstFailure().validate()) {
        console.log('Error: ', validator.errors().first());
    }

Sometimes you may wish to stop running validation rules on an attribute after the first validation failure. To do so, assign the bail rule to the attribute.

    validator.setRules({
        name: 'bail|required|string|min:3',
        email: 'bail|required|email',
        age: 'min:18'
    });

While the bail rule only stops a specific field when it encounters a validation failure, the stopOnFirstFailure method will inform the validator that it should stop validating all attributes once a single validation failure has occurred.

A Note On Nested Attributes

If the upcoming HTTP request contains "nested" field data, you may specify these fields in your validation rule using the "dot" syntax.

     validator.setRules({
        title: 'required|max:255',
        'author.name': 'required',
        'author.description': 'required',
    });