Symfony: How to handle common request scope data

Question

I'm migrating a legacy PHP project (pre-OO) to Symfony2. On every request I have to:

compute some dynamic data (depending on the current date and/or some request parameter)
use that data (multiple times!) in the rendered response.

A naive approach would be:

At the start of every controller method, call some global helper function to compute the data.
At the end of every controller method, pass the data as a parameter to the twig template.

Sounds tedious. Maybe it would be better to:

Create a subscriber for request events that computes the data when a request comes in and provides access to it via getter methods.
Define that subscriber/service as a global twig variable in config.yml.
In twig templates, call the getter methods on that service as needed.

Is that viable? In particular, are the twig variable/service and the subscriber always identical? Or could the service be a newly created instance?

Is this some sort of misuse? Or is there an officially recommended way for such a use case?

EDIT The data is not only needed in every twig template but in some controllers, too.

If you only need this information in twig templates then just create a twig extension and add your getters there. That eliminates the need for a subscriber. I would suggest taking the time to see if you really need this sort of data. I know you are dealing with a legacy app but there may be better designs. — Cerad
– Cerad, Commented Nov 1, 2016 at 13:07
Unfortunately, this information is also needed in some controllers. Edited my question accordingly. — thofou76
– thofou76, Commented Nov 1, 2016 at 13:27
In which case, a Subscriber is your starting point. Not a big fan of having a bunch of global data so be careful. Globals can make your code difficult to maintain. — Cerad
– Cerad, Commented Nov 1, 2016 at 13:44

Community · Accepted Answer · 2017-05-23 12:09:32Z

0

Calling a specific method in every Controller-Action would really be a bad solution. Your solution to use a subscriber isn't perfect either.

Without knowing your use-case in detail it´s hard to find a suitable way. Maybe one approach would be to write a Twig-Extension and injecting a Service into this Extension. The Service would get the Request-Stack via Dependency-Injection and compute the relevant Data. You could then access this data "on demand" through the Twig-Extension during the rendering.
Another approach could be using sub-requests during the rendering (Symfony: How to handle common request scope data)

Maybe these tips already helped you a bit. Otherwise let me know more details, where / how you need the data during the rendering.

edited May 23, 2017 at 12:09

CommunityBot

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answered Nov 1, 2016 at 12:45

Justus Klein

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4 Comments

thofou76 Over a year ago

I forgot to mention that the dynamic data will be needed in some controllers, too... What are your objections to subscribers?

Justus Klein Over a year ago

I dont understand how you would pass the data from your subscriber into your controllers / rendering process. The only way I can imagine is using global vars or something like that. And that's definitely a bad solution.

Justus Klein Over a year ago

If you want to access that data in your controllers, too, I would recommend using a central service and injecting the request-stack into it, as described above. Than simply use that service in your controllers and your twig-extension. The calculations for that data can be done on demand if accessed and if needed it can also be cached quite easily.

thofou76 Over a year ago

Ah! Just looked up request_stack and think it's better than my subscriber. Will try that. Thanks!

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