Translating WFFM 8.1 MVC forms error messages part II

Multilingual WFFM

The first post in this duo-series of posts handled the client-side validation of Sitecore's WebForms for Marketers. In this post I want to focus on the server-side error messages: changing them, translating them and the pitfalls you might encounter doing so.

Server-side validation and error messages

Server side validation is a must in forms - no need to tell you that. When using MVC forms you can alter the default messages here:

/sitecore/system/Modules/Web Forms for Marketers/Settings/Meta data/Mvc Validation Error Messages

Translating

As the "value" field of these items is not shared, one would assume that translating the error messages is nothing more than creating versions in other languages and filling in your translated message.
And yes, at first sight you might think that works as you will get to see error messages in a language that could be something else then English and could be even the current language. But it all depends on.. whether you were the first one to request the error messages. As far as we could detect, WFFM caches the error messages but forgot to take the language into account when caching...

So, how do we fix this? Luckily there is a way out. In the documentation of wffm 2.x the "Custom Errors" are mentioned and they are still present in 8.1...

Custom errors

Custom errors are items that can be used as error messages. A few ones exist and you can create more if needed. We used the available custom required and created a new custom email to test.

The items have a key: just look at the regular error message that you would like to use and copy the key (e.g. DynamicRequiredAttribute or DynamicEmailAttribute). In the "value" field you enter your custom message. 

Now create versions for all languages and translate the message as needed.

Using the custom errors

After creating custom error messages, we need to tell our forms to use them. Unfortunately this needs to be done for every field...

In the content editor go to your (required) field. Find the "Dictionary" section and select the desired entries from the list of all custom errors. In many cases that will just be the Custom required, but on an email field you can select for example Custom required and Custom email. Once you've done this for all your fields you're good to go.

Just don't forget to publish all your changes...