dede channel runphp

Of course! Let's dive deep into dede:channel and its runphp attribute. This is a powerful and frequently used feature in DedeCMS for creating custom navigation menus and dynamic channel lists.

What is dede:channel?

First, dede:channel is a DedeCMS tag used to display a list of channels (also called categories or sections). By default, it simply lists the names of the top-level channels in your site.

Basic Example:

{dede:channel}
    <a href='[field:typelink/]'>[field:typename/]</a>
{/dede:channel}

This would output something like:

<a href='/company/'>关于我们</a>
<a href='/news/'>新闻中心</a>
<a href='/products/'>产品展示</a>

What is the runphp attribute?

The runphp='yes' attribute fundamentally changes how the dede:channel tag works. Instead of just outputting the channel data directly, it tells DedeCMS to execute a block of PHP code for each channel in the list.

This allows you to perform complex logic, such as:

• Checking if the current page matches the channel.
• Dynamically adding CSS classes (e.g., current, active, menu-item-has-children).
• Generating different HTML for different channels.
• Checking if a channel has child channels (sub-categories).

When runphp='yes' is used, the content between {dede:channel} and {/dede:channel} is treated as PHP code. The channel's data (like id, typename, typelink, etc.) is made available as PHP variables, which you can then manipulate.

How to Use runphp: A Step-by-Step Guide

Let's go through the most common use case: creating a navigation menu where the "current" channel is highlighted with a CSS class.

Step 1: The Basic Channel Tag Structure

Start with your basic channel list. We'll use an unordered list (<ul>) for good practice.

<ul id="nav">
    {dede:channel type='top'}
        <li><a href="[field:typelink/]">[field:typename/]</a></li>
    {/dede:channel}
</ul>

• type='top': This tells DedeCMS to only show the top-level channels. You can omit this to show all channels.

Step 2: Add runphp='yes'

Now, add the runphp attribute to the opening tag. We'll also wrap the <li> in <?php ... ?> to make our PHP code clear.

<ul id="nav">
    {dede:channel type='top' runphp='yes'}
        <?php
            // PHP code will go here
        ?>
    {/dede:channel}
</ul>

Step 3: Access Channel Data in PHP

When runphp is active, the field data from each channel is automatically available as PHP variables. The variable names are prefixed with $this->.

• Channel ID: $this->Fields['id']
• Channel Name: $this->Fields['typename']
• Channel Link: $this->Fields['typelink']
• Channel Type ID: $this->Fields['typeid'] (useful for comparison)

You can also use the shorthand $fields array, which is often more convenient:

• $fields['id']
• $fields['typename']
• $fields['typelink']

Step 4: Write the PHP Logic

Here is the complete PHP code to check if the current page is the channel page and apply a class="current" if it is.

<ul id="nav">
    {dede:channel type='top' runphp='yes'}
        <?php
            // Get the current channel's ID from the PHP variable
            $currentTypeId = $this->Fields['typeid'];
            // Get the ID of the channel being viewed on the page.
            // This is a global DedeCMS variable.
            $globalTypeId = $GLOBALS['typeid'];
            // Initialize a variable to hold our class name
            $liClass = '';
            // Compare the two IDs
            if ($currentTypeId == $globalTypeId) {
                // If they match, it's the current channel
                $liClass = ' class="current"';
            }
            // Construct the final HTML for the list item
            // We use @me to output the result
            @me = "<li{$liClass}><a href=\"" . $this->Fields['typelink'] . "\">" . $this->Fields['typename'] . "</a></li>";
        ?>
    {/dede:channel}
</ul>

Explanation:

1. $this->Fields['typeid']: Gets the ID of the channel we are currently looping through.
2. $GLOBALS['typeid']: This is a special DedeCMS variable that holds the ID of the channel or article being displayed on the page.
3. if ($currentTypeId == $globalTypeId): This is the core logic. It checks if the channel in our loop is the same as the one being viewed.
4. $liClass = ' class="current"': If the condition is true, we set the $liClass variable to our desired CSS class.
5. @me = "...": This is the most important part. In runphp blocks, you must assign your final output string to the special variable @me. Whatever is in @me will be rendered on the page.

More Advanced Examples

Example 1: Creating a Dropdown Menu (Checking for Sub-Channels)

This example checks if a channel has children and adds a has-children class. It also uses another DedeCMS tag, dede:sonchannel, inside the PHP block to list the sub-channels.

{dede:channel type='top' runphp='yes'}
    <?php
        $typeid = $this->Fields['id'];
        $typename = $this->Fields['typename'];
        $typelink = $this->Fields['typelink'];
        $hasChildren = false;
        $subChannelsHtml = '';
        // Use the global object to query for sub-channels
        $dsql = new DedeSql(false);
        $dsql->SetQuery("SELECT id,typename,typedir FROM `#@__arctype` WHERE reid = $typeid AND ishidden<>1 ORDER BY sortrank");
        $dsql->Execute('t');
        if ($dsql->GetTotalRow() > 0) {
            $hasChildren = true;
            $subChannelsHtml = '<ul class="sub-menu">';
            while ($row = $dsql->GetArray('t')) {
                $subChannelsHtml .= "<li><a href='{$row['typedir']}'>{$row['typename']}</a></li>";
            }
            $subChannelsHtml .= '</ul>';
        }
        $dsql->Close();
        $liClass = ($hasChildren) ? ' class="menu-item-has-children"' : '';
        @me = "<li{$liClass}>"
            . "<a href=\"{$typelink}\">{$typename}</a>"
            . $subChannelsHtml
            . "</li>";
    ?>
{/dede:channel}

Example 2: Applying Different Logic Based on Channel ID

You can use a switch statement to create completely different HTML for specific channels.

{dede:channel type='top' runphp='yes'}
    <?php
        $typeid = $this->Fields['id'];
        $typename = $this->Fields['typename'];
        $typelink = $this->Fields['typelink'];
        switch ($typeid) {
            case 1: // ID 1 is the "Home" page
                @me = "<li><a href='/'>首页</a></li>";
                break;
            case 5: // ID 5 is the "Contact Us" page
                @me = "<li class='contact-link'><a href='{$typelink}'>联系我们</a></li>";
                break;
            default: // All other channels
                @me = "<li><a href='{$typelink}'>{$typename}</a></li>";
                break;
        }
    ?>
{/dede:channel}

Key Takeaways

1. Enable PHP: Use runphp='yes' on the {dede:channel} tag.
2. Use PHP Tags: Wrap your logic in <?php ... ?>.
3. Access Data: Use $this->Fields['fieldname'] or $fields['fieldname'] to get channel information.
4. Use Global Variables: Use $GLOBALS['typeid'] to get the ID of the current page.
5. Output with @me: Always assign your final HTML string to the @me variable to make it visible on the page.
6. Debugging: If your code doesn't work, check for PHP syntax errors. You can also temporarily use echo $this->Fields['typename']; inside the runphp block to see if it's looping correctly.