GROQ query to filter blog posts by category slug

Hey there! I can help you with that. To filter blog posts by a category with a specific slug, you need to use the reference access operator (->) in your GROQ query to dereference the category reference and access its slug field.

Here's the query you need:

*[_type == "post" && category->slug.current == "content-marketing"]

Let me break this down:

• *[_type == "post"...] - Filters all documents of type "post" (adjust "post" to match your blog post document type)
• category-> - The reference access operator dereferences your category reference to access the actual category document
• slug.current == "content-marketing" - Accesses the slug field (typically stored as slug.current in Sanity) and checks if it equals "content-marketing"

If you want to include the full category data in your results, you can add a projection:

*[_type == "post" && category->slug.current == "content-marketing"] {
  _id,
  title,
  category->,
  // other fields you need
}

Common issues to watch out for:

1. Make sure your document type name matches (might be "blogPost" or "article" instead of "post")
2. The slug field is usually slug.current, not just slug
3. If the category field is an array of references, use "content-marketing" in category[]->slug.current instead

You can test this query in Sanity Vision (the Vision plugin in your Studio) to make sure it returns the right results before using it in your code.

Let me know if you're still having issues and I can help you troubleshoot further!