GROQ query: Filter documents where array field intersects with parameter array

Perfect! I found the exact solution to your problem. The trick is to use the count() function combined with the @ filter operator to check if any elements from one array exist in another array.

Here's how to solve your problem:

*[_type == 'blog' && count(categories[@ in $categories]) > 0] {
  _id,
  _updatedAt,
  categories,
  description,
  title,
  timeToRead,
  publishedAt,
}

Where $categories is your array parameter (e.g., ["Design", "Research"]).

How it works:

The expression categories[@ in $categories] filters the categories array to only include elements that exist in your $categories parameter array. Then count() counts how many matches there are. If the count is greater than 0, it means at least one category matches, and that blog post is included in the results.

Example:

• If a blog has categories: ["Design", "UX", "Frontend"]
• And you pass $categories: ["Design", "Research"]
• The expression categories[@ in $categories] evaluates to ["Design"]
• count(["Design"]) returns 1
• Since 1 > 0, this blog is included in results

This is exactly the "array intersection" check you need! The @ symbol in GROQ represents the current element being iterated over, and the in operator checks if that element exists in the comparison array.

This pattern comes from this community discussion about comparing arrays and checking for string overlap in GROQ queries, which is exactly your use case.

You can test this in Vision (Sanity's query testing tool) with your parameters to verify it works as expected!