On page 262, the provided HTML code contains a gender-related form code which is not yet implemented in the corresponding view. So the below statement on page 264:
Now, if we visit /admin/dashboard and select an age group filter from the drop down menu, we should see the chart render again with appropriately filtered data…
is not correct. We have not implemented the handler for gender selection and it would be wiser to postpone the HTML code for gender selection and remove it:
<div>
<.form
for={%{}}
as={:gender_filter}
phx-change="gender_filter"
phx-target={@myself}
id="gender-form"
>
<label>By gender:</label>
<select name="gender_filter" id="gender_filter">
<%= for gender <-
[
"all",
"female",
"male",
"other",
"prefer not to say"
] do %>
<option value={gender} selected={@gender_filter == gender}>
<%= gender %>
</option>
<% end %>
</select>
</.form>
</div>