GraphQL Conditional Queries

This is possible-it would have to be different. Your query wouldn't be a valid GQL query. Something like this would:

    {
      users(where: {age: { $gt: 18 }}){ #inspired by mongoDB query api
        name
        age
      }
    }

or maybe simpler:

   {
     users(where: {age: ">18"}}){
        name
        age
      }
   }

of course either way the resolver on the backend needs to expect this where argument on the users field and construct the DB query accordingly when it is passed. You would not find this in GraphQL docs because GraphQL itself doesn't care about that. It only showcases how to use features of GraphQL.

If you tried example projects like for example star was api, those don't have any filtering built in.

You should send your age filter as a parameter.You might try the following one:

In your graphql file

type users {
 name: String,
 age: Int,
 ...
}

usersQuery(ageLimit: Int): [users]

also you can send '>' , '<' , '=' as a parameter. Also it seems like that

usersQuery(ageLimit: Int, ageOperator: String): [users]

and you should configure your resolver where statement with these operators. hope it helps you.