Gatsbyjs GraphQL Filtering on Multiple Fields

I use GatsbyJS to create my blog. One of the things that bugged me which I could not find a definite answer for online was how do you filter by more than one field in your GraphQL queries?

For example I have:

{
  allMarkdownRemark(
    filter: { id: { regex: "//posts|pages//" } }
    sort: { fields: [frontmatter___date], order: DESC }
  ) {
    edges {
      node {
        objectID: id
        fields {
          slug
        }
        internal {
          content
        }
        frontmatter {
          title
          subTitle
        }
      }
    }
  }
}

In the above I am filtering out anything that is a post or page but I also want to only return posts/pages that have been published. In my case I control this using the frontmatter publish field which is true or false. After a bit of Googling I tried to simply add a comma after the first filter's } and it worked!

{
  allMarkdownRemark(
    filter: { id: { regex: "//posts|pages//" }, frontmatter: { publish: { eq: true } } }
    sort: { fields: [frontmatter___date], order: DESC }
  ) {
    edges {
      node {
        objectID: id
        fields {
          slug
        }
        internal {
          content
        }
        frontmatter {
          title
          subTitle
        }
      }
    }
  }
}

While GraphQL is JSON like it is not JSON, but it has similar syntax in some cases it seems like listing multiple properties in a JSON object for example.

I have not worked with GraphQL outside of GatsbyJS but I do not think this will work on vanilla GraphQL as GatsbyJS uses Sift to give GraphQL more MongoDB query capabilities including filtering as described here:

Gatsby relies on Sift to enable MongoDB-like query syntax for object filtering.