Plugin API » Templates » Template functions » Language functions » ifContent()

ifContent() & markContent()

Sometimes rendering of part of a template is dependent on there being some content to display within it, but writing the conditional statements is non-trivial.

A pair of template functions, ifContent() and markContent() are provided to make these templates more concise and remove logic from the controller. In particular, it is hard to determine whether a deferred render will actually render anything without rendering it, and these functions make it considerably easier to surround them with containing HTML elements.

ifContent() contains the entire section in an anonymous block. Unless there is at least one markContent() where the anonymous block renders at least one character (whether whitespace or not), the entire section is efficiently removed.

There can be multiple markContent() blocks within a single ifContent() block, and ifContent() may be nested.

It is important to note that the anonymous block is actually rendered, but the rendered HTML is thrown away if there is no non-empty marked content. As usual, rendering the views should not have any side effects.

Example

Given a view with a name, and two deferred renders, description and location, this template will render the heading and enclosing <div> elements if and only if at least one of the deferred renders have content.

ifContent() {
  <div class="event-information">
    <h1> name </h1>
    markContent() {
      ifContent() {
        <div class="description">
          <div> "Description" </div>
          markContent() {
            render(description)
          }
        </div>
      }
    }
    markContent() {
      ifContent() {
        <div class="location">
          <div> "Location" </div>
          markContent() {
            render(location)
          }
        </div>
      }
    }
  </div>
}

The ifContent() function renders a container and a heading if and only if there is at least one deferred render which renders content.

There are multiple markContent() functions within the to level ifContent(). One or both of those must render something for the top level container to be included in the rendered HTML.

Within the top level ifContent() block, there are two more independent nested ifContent() blocks, which use ifContent() and markContent() pairs around the deferred renders to control rendering them in containers. If the deferred renders render something, the containing <div> elements and text will be output too.