m_persistent

• Module: core

This implements persistent storage of values between visits from the same browser.

Persistent storage is implemented using a cookie and database storage. The cookie contains the key for the stored values. If a visitor makes a request then the session will load the persistent values into the session process. These can then be accesses using {{ m.persistent.yourkey }} in templates (replace yourkey with the key you used to store the information).

The persistent cookie (z_pid) is only set if persistent information is saved. This can be done using calls zo z_context:set_persistent/3 or the action persistent_set.

Retrieve a value with z_context:get_persistent/2 or the m_persistent.

Note that the first time a persistent value also a cookie needs to be set. This cookie will be added to the Context passed to the set_peristent call. If this was a regular request (HTTP or Ajax) then the cookie will be returned in the request reply. If the request was a Websocket request then the user-agent will make a call back to the server to retrieve (and set) the new persistent cookie.