GROQ: Conditionally return referenced documents based on boolean value

You can use the select() function in GROQ to conditionally return an array based on a boolean value. The select() function works like a switch statement and evaluates conditions in order, returning the first matching value.

For your use case of showing/hiding the 3 most recent blog posts based on a boolean, here's how to structure it:

*[_id == "homepage"][0] {
  ...,
  "posts": select(
    showBlogPosts == true => *[_type == 'post'] | order(publishedAt desc) [0..2] {
      title,
      slug,
      publishedAt
    },
    []
  )
}

This query:

• Checks if showBlogPosts is true
• If true, returns an array of the 3 most recent posts
• If false (or undefined), returns an empty array []

You can also use a more concise version if your boolean field might be undefined:

*[_id == "homepage"][0] {
  ...,
  "posts": select(
    defined(showBlogPosts) && showBlogPosts => *[_type == 'post'] | order(publishedAt desc) [0..2] { ... },
    []
  )
}

The key differences from your original attempt:

1. Use the select() function with a condition-value pair syntax: condition => value
2. The condition checks your boolean field directly
3. Provide a fallback value (empty array) when the condition is false
4. The entire subquery goes after the => arrow

You can also use this pattern within projections if you have multiple features to toggle:

*[_id == "homepage"][0] {
  title,
  "blogSection": select(showBlogPosts => {
    "posts": *[_type == 'post'] | order(publishedAt desc) [0..2] { ... }
  }),
  "newsSection": select(showNews => {
    "items": *[_type == 'news'] | order(_createdAt desc) [0..5] { ... }
  })
}

This gives your clients flexible control over which content sections appear on the homepage!