Polls module

Maintainer

Mateusz Uzdowski

Requirements

master: SilverStripe 3.0.x 0.1: SilverStripe 2.4.x

Installation

1. Include the module folder in your project root folder and rename it to "polls"
2. Rebuild database schema (dev/build?flush=1)

Features

• By default, each visitor, determined by browser cookie, can only vote once
• Uses Google chart API
• Supports single and multiple-choice polls

Usage

CMS usage

1. Log in the CMS
2. Go to the Poll section
3. Create a poll, press Add, then add a few poll options
4. The further steps depend on how the PollForm has been implemented

Connect Poll object with PollForm

The PollForm knows how to render itself, and is able to render both the selection form and the chart. It needs to get a Poll object as its input though, and it's up to you to provide it: it will depend on your project how you will want to do this.

Here is the most basic example of how to associate one Poll with each Page:

class Page extends SiteTree {
    static $has_one = array(
        'Poll' => 'Poll'
    );

    ...

    function getCMSFields() {
        $fields = parent::getCMSFields();

        $polls = Poll::get();
        if ($polls) { 
            $fields->addFieldsToTab('Root.Main', array(
                DropdownField::create('PollID', 'Poll', $polls->map(), $this->PollID)->setEmptyString('--- Select a poll ---'),
            ));
        }
        else {
            $fields->addFieldsToTab('Root.Main', array(
                new LiteralField('Heading', '<h1>No polls available</h1>'),
                new LiteralField('PollID', '<p>There are no polls available. Please use <a href="admin/polls">the polls
                    section</a> to add them.</p>')
            ));
        }

        return $fields;
    }

    ...
}

Now you should be able to visit your page in the CMS and select the poll from the new dropdown.

Embed PollForm in your template

Here's a suggestion how to create and expose a PollForm to all your templates:

class Page_Controller extends ContentController {
    ...

    function PollForm() {
        $pollForm = new PollForm($this, 'PollForm', $this->Poll()); 
        // Customise some options
        $pollForm->setChartOption('height', 300);
        $pollForm->setChartOption('width', 300);
        $pollForm->setChartOption('colours', array('FF0000', '00FF00'));
        return $pollForm;
    }

    ...
}

You will then be able to embed this form in your template like that:

$PollForm

This allows you to specify where you want the poll to show up. The poll will not appear if the related SiteTree object has no poll associated with it (i.e. $this->Poll() is empty).

Customise the chart

You can obtain a good deal of control by redefining the PollForm.ss template in your theme folder. Here is the default setup:

<% if $Poll.Visible %>
    <h3>$Poll.Title</h3>
    <% if $Image %>
        $Poll.Image.ResizedImage(300,200)
    <% end_if %>
    <% if $Description %>
        $Poll.Description
    <% end_if %>

    <% if $Poll.hasVoted %>
        $Chart
    <% else %>
        $DefaultForm
    <% end_if %>
<% end_if %>

And here is advanced setup that renders the poll as simple HTML blocks, using some of polls API functions:

<% if $Poll.Visible %>
    <div class="poll">
        <% if $Poll.Image %>
            <div class="thumbnail">
                <img src="<% control Poll.Image %>$CroppedImage(150,50).URL<% end_control %>" alt="$Title"/>
            </div>
        <% end_if %>
        <% if $Poll.Title %>
            <h3>$Poll.Title</h3>
        <% end_if %>
        <% if $Poll.Description %>
            <p>$Poll.Description<br/></p>
        <% end_if %>

        <% if $shouldShowResults %>
            <div class='poll-results'>
                <% control Poll.Choices %>
                    <div class='poll-results-entry poll-results-entry-$EvenOdd'>
                        <span><em>$Title $PercentageOfTotal ($Votes):</em></span>
                        <div style='width: $PercentageOfMax;'>&nbsp;</div>
                    </div>
                <% end_control %>
            </div>
        <% else %>
            $DefaultForm
        <% end_if %>

        <p class='poll-total'>Total votes: $Poll.TotalVotes</p>
    </div>
<% end_if %>

If you want to make a site-wide changes, you can use a decorator and define replaceChart function. For example the following will give you a text-only rendering of results:

class PollFormDecorator extends DataObjectDecorator {
    function replaceChart() {
        $choices = $this->owner->Poll()->Choices('', '"Order" ASC');

        $results = array();
        if ($choices) foreach($choices as $choice) {
            $results[] = "{$choice->Title}: {$choice->Votes}";
        }

        return implode($results, '<br/>');
    }
}

Object::add_extension('PollForm', 'PollFormDecorator');

Finally, for a full control of the poll form and the results subclass the PollForm - you can then create form-specific templates or work on the basis of redefining the getChart method. This way you can also create multiple parallel presentation layers for the polls.

Custom Vote Handling

Using the Vote_Backend we can define our own vote handler. The votehandler takes care of storing votes and the logic of whether a user has voted before.

See DatabaseVoteHandler for an example.