Phoenix LiveView Demystified

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Alex Garibay DockYard | Phoenix Core @_alexgaribay alexgaribay

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Phoenix LiveView [is a library that] enables rich, real-time user experiences with server- rendered HTML. ” “

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Less of this

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More of this!

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But how?

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No content

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Live EEx Phoenix Channels JavaScript

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Live EEx

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clock.html.leex ~L"""

The time is <%= @time %>.

"""

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Live EEx at Compile-time

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~L""" Hello, <%= @name %>. """

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[ "Hello, ", {:@, [line: 11], [{:name, [line: 11], nil}]}, "." ] ~L""" Hello, <%= @name %>. """

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# Statics and Vars [ "Hello, ", {:arg0, [], Phoenix.LiveView.Engine}, "." ] # Dynamics [ {:=, [], [ {:arg0, [], Phoenix.LiveView.Engine}, {{:., [], [Phoenix.LiveView.Engine, :to_safe]}, [], [{:@, [line: 11], [{:name, [line: 11], nil}]}]} ] } ]

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arg0 = case(Phoenix.LiveView.Engine.changed_assign?(__changed__, :name)) do true -> case(__prints__) do %{0 => {_, _} = print} -> Process.put({Phoenix.LiveView.Engine, :fingerprint}, print) %{} -> :ok end case(Phoenix.LiveView.Engine.fetch_assign!(assigns, :name)) do %{__struct__: Phoenix.LiveView.Rendered} = other -> other {:safe, data} -> data bin when is_binary(bin) -> Plug.HTML.html_escape_to_iodata(bin) other -> Phoenix.HTML.Safe.to_iodata(other) end false -> nil end

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%Phoenix.LiveView.Rendered{ static: [ "Hello, ", "." ], dynamic: [ ] fingerprint: 216187664090110924469697367378888494464 } arg0

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%Phoenix.LiveView.Rendered{ static: [ "Hello, ", "." ], dynamic: [ ] fingerprint: 216187664090110924469697367378888494464 } "ElixirConf"

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iodata nil %Phoenix.LiveView.Rendered{} %Phoenix.LiveView.Comprehension{}

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<%= for point <- @points do %> x: <%= point.x %> y: <%= point.y %> <% end %>

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<%= for point <- @points do %> x: <%= point.x %> y: <%= point.y %> <% end %> points = [ %{x: 1, y: 2}, %{x: 3, y: 4} ] !20

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%Phoenix.LiveView.Comprehension{ static: [ "\n x: ", "\n y: ", "\n" ], dynamics: [ ["1", "2"], ["3", "4"] ] }

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Mounting to the DOM

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# In a router live "/", ClockLive # In a controller live_render(conn, ClockLive, session: %{}) # In a template live_render(conn, ClockLive, session: %{})

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container: {:p, class: "rounded"}

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container: {:p, class: "rounded"}

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Phoenix Channels

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socket "/live", Phoenix.LiveView.Socket

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channel "lv:*", Phoenix.LiveView.Channel

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"lv:phx-xeR6nJ8t"

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"lv:phx-xeR6nJ8t" %{ # Params from JavaScript LiveSocket object "params" => %{ "timezone" => “America/Denver" }, # data-phx-session "session" => "SQyYk.g3QACZAN8XasAQ.RnkD" }

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"lv:phx-xeR6nJ8t" %{ # Params from JavaScript LiveSocket object "params" => %{ "timezone" => “America/Denver" }, # data-phx-session "session" => "SQyYk.g3QACZAN8XasAQ.RnkD" }

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"lv:phx-xeR6nJ8t" %{ # Params from JavaScript LiveSocket object "params" => %{ "timezone" => “America/Denver" }, # data-phx-session "session" => "SQyYk.g3QACZAN8XasAQ.RnkD" }

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"lv:phx-xeR6nJ8t" %{ # Params from JavaScript LiveSocket object "params" => %{ "timezone" => "America/Denver" }, # data-phx-session "session" => %{ id: "phx-xeR6nJ8t", parent_pid: nil, router: MyAppWeb.Router, session: %{}, view: MyAppWeb.ClockLive } }

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Click

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Click %Phoenix.Socket.Message{ event: "event", join_ref: "1", payload: %{ "event" => "my_click_event", "type" => "click", "value" => "button's value" }, ref: "2", topic: "lv:phx-xeR6nJ8t" }

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Click %Phoenix.Socket.Message{ event: "event", join_ref: "1", payload: %{ "event" => "my_click_event", "type" => "click", "value" => "button's value" }, ref: "2", topic: "lv:phx-xeR6nJ8t" }

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Click %Phoenix.Socket.Message{ event: "event", join_ref: "1", payload: %{ "event" => "my_click_event", "type" => "click", "value" => "button's value" }, ref: "2", topic: "lv:phx-xeR6nJ8t" }

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Click %Phoenix.Socket.Message{ event: "event", join_ref: "1", payload: %{ "event" => "my_click_event", "type" => "click", "value" => "button's value" }, ref: "2", topic: "lv:phx-xeR6nJ8t" } view_module.handle_event("my_click_event", "button's value", socket)

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JavaScript

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❤

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import LiveSocket from "phoenix_live_view" let liveSocket = new LiveSocket("/live") liveSocket.connect()

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import LiveSocket from "phoenix_live_view" let liveSocket = new LiveSocket("/live") liveSocket.connect()

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import LiveSocket from "phoenix_live_view" let liveSocket = new LiveSocket("/live") liveSocket.connect()

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const selector ='[data-phx-view]:not([data-phx-parent-id])' document.querySelectorAll(selector)

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let parent = null let href = window.location.href let view = new View(lvContainer, liveSocket, parent, href) view.join()

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let parent = null let href = window.location.href let view = new View(lvContainer, liveSocket, parent, href) view.join()

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let parent = null let href = window.location.href let view = new View(lvContainer, liveSocket, parent, href) view.join()

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{ "rendered": { "0": "10:10", "static": [ "

The time is ", ".

\n" ] } }

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{ "rendered": { "0": "10:10", "static": [ "

The time is ", ".

\n" ] } }

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{ "rendered": { "0": "10:10", "static": [ "

The time is ", ".

\n" ] } }

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{ "rendered": { "0": "10:10", "static": [ "

The time is ", ".

\n" ] } }

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let {rendered} = { "rendered": { "0": "10:10", "static": [ "

The time is ", ".

\n" ] } } let static = rendered.static

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let {rendered} = { "rendered": { "0": "10:10", "static": [ "

The time is ", ".

\n" ] } } let static = rendered.static static[0] + rendered[0] + static[1]

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The time is " + "10:10" + ".

\n"

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{ "rendered": { "0": "10:10", "static": [ "

The time is ", ".

\n" ] } }

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{ "rendered": { "0": "10:10", "static": [ "

The time is ", ".

\n" ] } } { "diff": { "0": "10:11" } }

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{ "rendered": { "0": "10:11", "static": [ "

The time is ", ".

\n" ] } }

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Morphdom.js

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var morphdom = require('morphdom') var source = document.createElement('p') source.innerHTML = 'The time is 10:10.' // '