haha, okay! at least i can retain some sanity.
Except now I realise I should be using the Commander subscribe. As this makes more sense.
doogs
doogs
Sorry, me again. So I have decided that the broadcast_poke/4 wont work for me. Having to set all the assigns just wont work in my case, as I need to know things like the currently logged in Staff user, which changes data in the view. @OvermindDL1 is there a way you know around this? can you explain the Shared Commanders model a bit more?
@grych I looked into the Drab.Elements as you suggested, and I can see that the Element broadcast_html might work. Although I have to broadcast a list of data, each will have a link on it which currently is built using the Phoenix link helpers and routing paths. Just seems a little messy.
Am I possibly not using Drab in the best use case here? Or am I thinking about this data in the wrong way?
grych
Creator of Drab
I believe the best thing you can do is to split you application into smaller templates. Then you may re-render them at the server side and send changed html to the browser, with broadcast_html.
Actually, there is an example for this on Drab demo page - it is not for broadcasting, but shows the idea of using small partials.
First, render the partial
buttons = render_to_string("waiter_example.html", [])
then, send it to the browser
insert_html socket, "#waiter_example_div", :beforeend, buttons
and at the end, remove them from the browser
set_prop socket, "#waiter_example_div", innerHTML: nil
(the last line should be replaced with set_html/3, when I wrote the example it did not exist yet).
grych
Creator of Drab
Re: shared commanders
It is always a good idea to split your application to chunks, which you can reuse in the future. Shared Commander can help you with this! Shared commanders are the pieces of frontend+backend code. This is a good example:
<p drab-commander="DrabPoc.Timer2Commander" drab-argument="{seconds: 10}">
<button class="btn btn-primary" drab-click="countdown">
Count down from 10
</button>
<br><span class="output">SPAN .output</span>
</p>
server side:
defhandler countdown(socket, sender, options) do
for i <- 1..options["seconds"] do
set_prop socket, this_commander(sender) <> " .output", innerText: options["seconds"] - i
Process.sleep(1000)
end
end
What is the most important here, is to understand this_commander/1 function. It gives you an unique selector of the node you are calling the countdown function from. This is how you may put many of those in the same page.
But your case is probably even easier, as you don’t want to react on the events from the Shared Commander, but just broadcast the updated data for all the servers. Consider you have a book partial:
<tr><td>
<span class="book-name" id="book_<%= @book_id %>"><%= @book_name %></span>
</td></tr>
and render it as a list:
<%= for {book_id, book_name} <- @books do %>
<%= render("book.html", book_id: book_id, book_name: book_name %>
<% end %>
now, when you want to refresh the specific book name, just use it’s id!
book_name = read_from_database(book_id)
broadcast_html same_topic("books"), "#book_#{book_id}", book_name
doogs
doogs
Do you have any issues with Tests?
During tests my broadcast is happening. The tests pass okay, which they should since I am only unit testing. But at the end of the test I get a termination error from my GenServer process that i am running.
The error is occurs after all tests pass, during the call my Drab broadcast function, which is doing this:
conn = %Plug.Conn{private: %{:phoenix_endpoint => BonusWeb.Endpoint}}
auction = Phoenix.View.render_to_string(BonusWeb.Staff.OfferView, "_auction.html", [active_offers: offers, conn: conn ])
Drab.Element.broadcast_html(Drab.Core.same_topic("brandname"), "#auction", auction)
The error basically says that im passing in Nil for the active_offers assigns.
Im figuring it has something to do with the DB timing of tests maybe? Have you seen this before?
Error:
21:31:48.592 [error] GenServer :auction terminating
** (MatchError) no match of right hand side value: nil
(bonus) lib/bonus/submissions/submissions.ex:229: Bonus.Submissions.current_winning_bid/1
(bonus) lib/bonus_web/views/shared_helpers.ex:32: BonusWeb.SharedHelpers.winning_bid/1
(bonus) lib/bonus_web/templates/staff/offer/_auction.html.eex:18: anonymous fn/3 in BonusWeb.Staff.OfferView."_auction.html"/1
grych
Creator of Drab
There are a lot of problems on tests, as most of them must be done with the chromedriver, and sometimes it just fails, but I’ve never seen anything like this.
Can you check what active_offers has before you render_to_string? If it is really nil, you shall check wherever this value comes from. From the test database which is empty?
doogs
I can inspect the result of render_to_string and it has the correct data in it.
Its weird. When I run a single test it passes. but when I run multiple tests (more than 1) it fails.
Does that mean anything to you? Im not really sure how the test environments are setup and pulled down. But somehow its breaking when running this code and multiple test:
conn = %Plug.Conn{private: %{:phoenix_endpoint => BonusWeb.Endpoint}}
auction = Phoenix.View.render_to_string(BonusWeb.Staff.OfferView, "_auction.html", [active_offers: offers, conn: conn ])
the render_to_string works on the first test, but then returns empty on every subsequent test. i am so confused.
doogs
After further investigation i have narrowed it down to this.
Sorry it doesnt seem to be Drab related, but ddint seem to be getting this issue before I added Drab. Which just seems odd.
But, when running more than 1 test, this code return nil
%{bids: bid} = get_offer(offer.id) |> Repo.preload([bids: order_bids_query])
If I change it to this it works:
%{bids: bid} = offer |> Repo.preload([bids: order_bids_query])
Seems that the call to get_offer fails when multiple tests run. which seems crazy, cause its pretty standard:
Repo.get(Offer, id) |> Repo.preload(:brands)
It seems that the database call must return nil, when it should return a result. then this is breaking the render_to_string call i imagine.
not sure best way to solve this. maybe i should be going to regular elixir chat support? 
thanks
grych
Creator of Drab
I would suggest asking here on the forum with “ecto” tag, as I assume this is Ecto related question. Sorry, I won’t help, as I’ve never used it before.