Using {{dc:post:excerpt}} in component parameters causes page crash

Support
#1

Hi, I ran into a strange error today: when I enter the following in a component’s parameters:
{
“Subline” : {
“label” : “Subline”,
“type” : “text”,
“initial” : “{{dc:post:excerpt}}”
}
}
…all pages using the component crash.
The problem is {{dc:post:excerpt}}; as soon as I use something like {{dc:post:title}}, for example, there is no issue.
Can you reproduce or explain this?

#2

Hey @Daryl_Shaw,

This crash is caused by an infinite recursion (infinite loop) during the layout rendering process.

Here is exactly why it happens:

1. The Recursive Loop ( ❴❴dc:post:excerpt❵❵ )

When a page containing the component is rendered, Cornerstone evaluates the component’s parameters, including the default/initial value of Subline which is set to ❴❴dc:post:excerpt❵❵ :

  1. Parameter Evaluation : Cornerstone attempts to resolve ❴❴dc:post:excerpt❵❵ for the current post.
  2. Retrieve Excerpt : The dynamic content resolver calls WordPress’s get_the_excerpt() function.
  3. Automatic Excerpt Generation : If the post does not have a manually crafted excerpt (in the WordPress Excerpt field), WordPress falls back to generating one from the post’s body ( post_content ).
  4. Executing ［cs_content］ : In the Pro theme / Cornerstone, the page content is wrapped inside the ［cs_content］ shortcode. To ensure that layout content is readable by search engines and excerpt generators, the theme hooks into strip_shortcodes_tagnames to prevent ［cs_content］ from being stripped.
  5. Render Content : Because it is not stripped, the ［cs_content］ shortcode executes, starting to render all the elements and components on the page again to extract text for the excerpt.
  6. Nested Evaluation : During this nested render, the layout engine encounters the same component and tries to evaluate its initial parameter values.
  7. Infinite Loop : Evaluating Subline triggers ❴❴dc:post:excerpt❵❵ again, which invokes get_the_excerpt() , which attempts to render the layout, which encounters the component, and so on.
  8. Crash : The execution stack overflows, causing PHP to exceed its maximum nesting level or run out of memory, crashing the page.

2. Why ❴❴dc:post:title❵❵ Works Fine

When you use ❴❴dc:post:title❵❵ :

  • The dynamic content parser resolves this via get_the_title( $post )
  • This function simply reads the database column for the title string and returns it directly. It never triggers the parsing or rendering of post_content (shortcodes), meaning no recursion loop is created.

Workarounds

  1. Avoid Self-Referencing Excerpts in Initial Values : Do not set the default/initial parameter of a component to ❴❴dc:post:excerpt❵❵ directly inside the parameter setup. Instead, set the default to an empty string or standard text, and pass the dynamic content tag only when implementing/consuming the component instance on the page.
  2. Add a Manual Excerpt : If the post/page using the component has a handcrafted manual excerpt defined in the WordPress post editor, WordPress will return it directly and bypass the automatic content parsing, which avoids the loop.
#3

Ok, thanks for quick response!

#4

You’re most welcome, @Daryl_Shaw.

#5

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