Allow html for options dropdown

[silviurosu]

I have a usecase for options to contain more than a text value. I want to be able to display an html I creating with label and sublabel.

I was able to display my own html sending the options like this:

  s = """
         <span>
          #{city}</br>
          <small>#{state}</small>
        </span>
        """
        {raw(s), city}

but there is a problem when selecting the option from dropdown. It tries to serialize the label as json and I get a crash:

[error] GenServer #PID<0.1414.0> terminating
** (Protocol.UndefinedError) protocol Jason.Encoder not implemented for {:safe, "<span>\n  Iaşi</br>\n  <small>Iaşi</small>\n</span>\n"} of type Tuple, Jason.Encoder protocol must always be explicitly implemented. This protocol is implemented for the following type(s): Any, Atom, BitString, Date, DateTime, Decimal, Ecto.Association.NotLoaded, Ecto.Schema.Metadata, Float, Integer, Jason.Fragment, Jason.OrderedObject, List, Map, NaiveDateTime, Recenza.Models.Service, Recenza.Models.Speciality, Time
    (jason 1.4.1) lib/jason.ex:213: Jason.encode_to_iodata!/2

[silviurosu]

I did some investigation myself and the issue comes from client_select method where it tries to push "select" event to server with this payload:

%{
  id: "search_component_city",
  input_event: true,
  mode: :single,
  parent_event: nil,
  selection: [
    %{
      label: {:safe, "<span>\n  Iaşi</br>\n  <small>Iaşi</small>\n</span>\n"},
      value: "Iaşi"
    }
  ]
}

I guess the problem lies in the fact that it tries to send back to the server the label and the value.
One idea would be to send the html as string without raw() but on UI to append raw automatically, or via a parameter.

[silviurosu]

Adding raw here:

<%= Phoenix.HTML.raw(option.label) %>

kind of works with the selection but after I select the value it shows the html as selected value which is not what I want.

I would nice to support an option to define templates like typeahead has:

templates: {
    empty: [
      '<div class="empty-message">',
        'unable to find any Best Picture winners that match the current query',
      '</div>'
    ].join('\n'),
    suggestion: Handlebars.compile('<div><strong>{{value}}</strong> – {{year}}</div>')
  }

In the same note it would be nice to highlight also the part of the text that matched.

[silviurosu]

I finally found how to do it reading though the code and test cases.
When I send the values to the component I can append extra keys to the map:

%{key: city, value: city, state: state}

then I can use the option tag to customize how it renders:

 <:option :let={option}>
      <span>
         <%= option.label %><br />
         <small><%= option.state %></small>
      </span>
</:option>

I guess this needs more documentation. Can I send a PR for that?
Thew only open question I have is how to highlight the part of the text that matches.

[maxmarcon]

Hi, glad you found the right way to render HTML in the options :)

Sure, go ahead and send a PR for the documentation if you feel it can be improved!

Regarding highlighting the matching part of the text: this can be done on the same lines of what you're doing to show your "option.state" label. One could add the matching prefix as an additional field to the option and then render accordingly.

Something like this:

<:option :let={%{label: label, matching_prefix: matching_prefix}}>
    <div><strong><%= matching_prefix %></strong><%= String.replace_prefix(label, matching_prefix, "") %></div>
</:option>

I could add a cheatsheet that shows how to do it. What do you think?

[silviurosu]

It would be good to add it to cheatsheet indeed. I was not able to find this from the documentation alone so it would help others