What would be the best way to persist a url parameter between links? Can I override Routes.x_path?

Questions / Help
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1

Let’s say I have a env param in my url, that could be prod/dev/ (this has nothing to do with my current env, it’s something the user would choose). I want to persist this between clicks, so if the current env is dev, I want Routes.some_path(@conn, :show, @thing, env: "dev") to act like this. Currently I do so with Routes.some_path(@conn, :show, @thing, env: @conn.params["env"]), but ideally I wouldn’t have to extract the env from the conn each time and remember to add it to each link, is there a better way to do this with Phoenix or Plug?

Also, If I have some links in the header, one for dev and one for prod, is there a way to use Phoenix’s path helpers to create a link to the current url, but with a new param? Like: Routes.current_path(@conn, env: "prod")?

2

Your use case seems very similar to how Gettext operates with Gettext.put_locale(locale) and Gettext.get_locale().

So, in a plug, you would set your param and everywhere thereafter you could read it.

Gettext stores the locale in the process dictionary.

But, honestly, I wouldn’t over complicate this if you can extract it from the conn params as you currently do. Why do you feel that’s a problem?

3

Is there a reason not to save the env in the session? That would be easier and more robust than add the param to every URL.

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4

Because I wouldn’t want User A to copy a link from their current page (User A has dev in their session), and send it to User B to edit (User B has prod in their session), and who therefore ends up editing their prod config when they thought they were accessing their dev config.

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5

Maybe then have a combination and if the param is in the link, then change the session

6

Would it be a possibility then to use a path namespace (/dev/... vs /prod/...), or subdomain (dev.example.com vs prod.example.com)? Don’t get me wrong, you probably have your good reasons for using a URL param, but I am just thinking that it would be much easier and robust to store this information elsewhere. My point is that, if you use a URL param, you have to remember to do that for literally every link (and form too), and only one missing place would be enough to break it.

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If the env needs to be in the url in order to correctly link to the right page, then I don’t see the point of also having it in the session. I think I’ll either just have to grab is from the conn each time I create a new link, or embed it directly into the url path itself.

8

Yeah, I think i’ll have to go with the first one. That’s how I had it before, but it made my routes and controllers a bit of a mess. Maybe I’ll add it to the end, so it’s /account/123/config/456/dev or /account/123/config/456/prod, instead of /.../?end=prod. I was just curious if there was a better was to handle it in the conn or route helpers, but it seems like adding it to the url path itself is the best way forward. Thanks.

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9

Routes.some_path is just a function; make a different one that does the conn.params["env"] dance and forwards all the rest of its arguments.