Displaying rethinkDB tables in real time in Phoenix Framework - real-time

Question

I'm attempting to go a step further from my previous question regarding tables from RethinkDB in Phoenix.
Now I'm attempting to retrieve them over a channel in order to display in real-time, new insertions to the table.
I'm already inserting into the table through the handle_in function:
def handle_in("new_person", %{"firstName" => firstName, "lastName" => lastName}, socket) do
broadcast! socket, "new_person", %{firstName: firstName, lastName: lastName}
table("users")
|> insert(%{first_name: firstName, last_name: lastName})
|> RethinkExample.Database.run
{:noreply, socket}
end
And in the app.js:
dbInsert.on("click", event => { //Detect a click on the dbInsert div (to act as a button)
//Use a module from the channel to create a new person
chan.push("new_person", {firstName: firstName.val(), lastName: lastName.val()});
// Clear the fields once the push has been made
firstName.val("");
lastName.val("");
});
chan.join().receive("ok", chan => {
console.log("Ok");
});
Which function should I use to handle the:
table("users")
|> RethinkExample.Database.run
And how should I render the data if it's now a channel and not html?
I can render the inserted person with HTML+Javascript but what I want is to retrieve the new user from the DB and render it with my other table results in real-time.
Here's how I'm at visually speaking:
users.html.eex
<div class="jumbotron">
<div id="userList">
<%= for %{"first_name" => first_name, "last_name" => last_name} <- #users.data do %>
<p><%= "#{first_name} #{last_name}" %>!</p>
<% end %>
</div>
</div>
<div class="dbOperation">
First name: <input type="text" id="firstName"><br>
Last name: <input type="text" id="lastName"><br>
<div id="dbInsert">Insert</div>
<br>
<div id="userToInsert">User to insert: </div>
</div>
user_controller.ex
defmodule RethinkExample.UsersController do
use RethinkExample.Web, :controller
use RethinkDB.Query
def users(conn, _params) do
# List all elements of a table from the database
q = table("users")
# Query for filtering results:
# |> filter(%{last_name: "Palmer"})
|> RethinkExample.Database.run #Run the query through the database
render conn, "users.html", users: q #Render users searched on the users template
end
end
people_channel.ex
defmodule RethinkExample.PeopleChannel do
use Phoenix.Channel
use RethinkDB.Query
#Handles the insert subtopic of people
def join("people:insert", auth_msg, socket) do
{:ok, socket}
end
# handles any other subtopic as the people ID, ie `"people:12"`, `"people:34"`
def join("people:" <> _private_room_id, _auth_msg, socket) do
{:error, %{reason: "unauthorized"}}
end
def handle_in("new_person", %{"firstName" => firstName, "lastName" => lastName}, socket) do
broadcast! socket, "new_person", %{firstName: firstName, lastName: lastName}
query = table("users")
|> insert(%{first_name: firstName, last_name: lastName})
|> RethinkExample.Database.run
new_person = %{"id": hd(query.data["generated_keys"]), "firstName": firstName, "lastName": lastName}
broadcast! socket, "new_person", new_person
{:noreply, socket}
end
def handle_out("new_person", payload, socket) do
push socket, "new_person", payload
{:noreply, socket}
end
end
app.js
import {Socket} from "phoenix"
let App = {
}
export default App
// Fetch fields from HTML through Jquery
let firstName = $("#firstName")
let lastName = $("#lastName")
let dbInsert = $("#dbInsert")
let userToInsert = $("#userToInsert")
let userList = $("#userList")
let socket = new Socket("/ws") //Declare a new socket
socket.connect() //Connect to the created socket
let chan = socket.chan("people:insert", {}) //Assign the people insertion channel to the socket
dbInsert.on("click", event => { //Detect a click on the dbInsert div (to act as a button)
//Use a module from the channel to create a new person
chan.push("new_person", {firstName: firstName.val(), lastName: lastName.val()});
// Clear the fields once the push has been made
firstName.val("");
lastName.val("");
})
chan.on("new_person", payload => {
userToInsert.append(`<br/>[${Date()}] ${payload.firstName} ${payload.lastName}`);
console.log("New Person", payload);
userList.append(`<br><p> ${payload.firstName} ${payload.lastName}!</p>`);
})
chan.join().receive("ok", chan => {
console.log("Ok");
})

Answer 1

You need a handle_out function in your channel that you listen to for the insert. If you use broadcast_from! then the sender will be excluded, if you use broadcast! then the sender will also receive the message.
Add the following to your channel:
def handle_out("new_person", payload, socket) do
push socket, "new_person", payload
{:noreply, socket}
end
And the following to your JS client:
chan.on("new_person", payload => {
console.log("New Person", payload);
});
The Channel documentation is available at http://www.phoenixframework.org/docs/channels
edit
When inserting a record in Rethink - the output looks like:
%RethinkDB.Record{data: %{"deleted" => 0, "errors" => 0,
"generated_keys" => ["7136199a-564b-42af-ad49-5c84cbd5b3e7"],
"inserted" => 1, "replaced" => 0, "skipped" => 0, "unchanged" => 0}}
We know that the data you get back from a rethink query looks like:
{"first_name" => "John",
"id" => "57c5d0d2-5285-4a24-a999-8bb7e2081661", "last_name" => "Smith"},
So - to broadcast the new record to the browser, we want to replicate this data structure so if you change your handle_in function to:
def handle_in("new_person", %{"firstName" => first_name, "lastName" => last_name}, socket) do
query = table("users")
|> insert(%{first_name: firstName, last_name: lastName})
|> RethinkExample.Database.run
new_person = %{"id": hd(query.data["generated_keys"]), "first_name": first_name, "last_name": last_name}
broadcast! socket, "new_person", new_person
{:noreply, socket}
end
Then - if you follow the steps above with the handle_out and chat.on then you will see the person logged out in your JavaScript console. From there - you can append it to your DOM using Javascript.