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This section describes the two different kinds of validations that are executed every time data has to be validated. The first one is mandatory while the second only applies if a validation flow is associated with a step.

Form rules

This first validation checks that the provided data satisfies the basic rules defined for each field of the current form (see Fields section) and it is performed every time data is sent to the backend.

As frontend validation does not guarantee its validity because requests can be manipulated, these rules are validated again on the server side when the request is received.

Client side

As we have just mentioned, our SDK automatically verifies that the input your users have provided is valid every time data is sent to the backend. These validations are performed on browsers without network dependency to reduce the time spent on validating the input as much as possible.

In case the user did not provide all the required fields or any field is not valid, a generic error message plus specific ones for each invalid field are displayed automatically. Nevertheless, if everything is ok, the process continues by sending the data to the backend.

When a field is not valid and the user modifies its value, we immediately check if it is valid to remove the error message as soon as possible even if the user did not try to continue pressing the button.

Server side

Despite the basic rules being validated locally, we validate the data again in our backend to make sure nobody tries to send invalid data manipulating the request nor the form rules has been modified at the same time that someone was modifying the form in the control panel.

The procedure when one or more errors are detected is the same as on the client side — we display a generic error message plus specific ones for each invalid field.

Validation flows

As soon as you collect leads or process sign-ups using our forms, you have to execute validations against external systems to detect existing accounts, verify emails or check promotional codes. All those validations can be done using our powerful Flows module.

Securing business

Unlike other competitors, your advanced validations are executed on the server side, protecting your API keys, internal web services or third-party providers from potential attacks.

Imagine you do not allow people to request a limited gift without a promotional code and that check depends on an authenticated external web service. If that validation is done on the client side, any beginner hacker would be able to bypass the validation or use that API key for malicious actions.

Fortunately, you will not have that problem because we would validate your promotional code on the server side.

Custom messages

As you have to implement your own custom validations, you have to specify your custom error messages too. Our flows allow you to specify the result (success or failure) plus the error message you want to display.

Furthermore, you can refer to user input or external error codes because Arengu responses support text templates with variable replacement.

Data signature

Your form can contain more than one validation flow and you do not need to validate all the previous data repeatedly. Once the data is validated by the flow, a temporary signature is generated. This signature confirms that all the data sent until that moment is valid.

On following validations, SDK sends the form data plus the most recent signature, so we automatically check that the previous data was not manipulated and you can focus on validating new data. If the previous data has been altered, the request will be blocked and an error message will be displayed.

This security mechanism is completely compatible with changes done by the user, including form navigation, such as going back to previous steps and going forward again. The previous step would be validated on the server side and, after confirmation, the current step will be validated by using the latest signature instead of an old one.

Final submission

If your form contains at least one validation flow, the signature will be verified at the end of the process to make sure that the sent data was not modified and that all the required validations were done. This process applies even if the last step does not have any validation flow.

If one or more validations were skipped, the backend will return an error message saying there are pending ones, so you do not have to verify that previous flows were executed either.

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