API and Web Application Interactions

There are three ways for communicating the user locale from the web application to the API:

  1. Requests with Accept-Language HTTP header for validation error messages.
  2. Query parameters when you cannot set the previous HTTP header (links, for instance).
  3. Update the user's locale via a GraphQL request if authenticated.
  4. Update the user's locale on login if the web application locale is not the same as the locale from the API

HTTP Header#

Use case: translating the validation error messages.

Each time the user changes its locale on the web application, the src/webapp/plugins/i18n.js plugin will update the HTTP header Accept-Language for the next GraphQL requests with the new value.

The LocaleSubscriber class from the API reads the value of this HTTP header to set the locale on its side.

Query Parameters#

In some use cases, you cannot set an HTTP header. For instance, when the user clicks on a link, you will have to use query parameters:

http://foo.bar/?locale=fr

In the Symfony Boilerplate, we use this solution for XLSX exports.

Authenticated user's locale#

As explained before, whenever an authenticated user changes the locale on the web application, we run the updateLocale GraphQL mutation.

In the API, the UpdateLocale use case updates the locale property of this user.

note

📣  This property helps to know in which locale the API has to translate emails for this user.

We also call the updateLocale GraphQL mutation on page src/webapp/pages/login.vue in the specific scenario where the web application locale is not the same as the user's locale from the API.

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