Lists and Non-Null

GraphQL defines type modifiers specifically for declaring that a field is a list or cannot be null. In a schema these are [T] and !. For example, a GraphQL schema might have the following.

enum Gender {
  Female
  Male
  NotSpecified
}

type Person {
  firstName: String!
  lastName: String!
  gender: Gender!
  friends: [Person]
}

The ! on all the fields tells API users that those fields will not be null. And the [] around the Person type on the friends field types the API users that the field returns a list of Person objects.

EntityGraphQL will automatically figure out fields that return lists based on if the resolve expression returns IEnumerable<T>.

Similarly, EntityGraphQL will mark non-nullable .NET types as non-null in thr GraphQL schema. If you need to change that, you can use field.IsNullable(bool).

Lets say we know a person's first and last name will never be null.

var type = schema.AddInputType<Person>("PersonInput", "New person data")
type.AddField("firstName", p => p.FirstName, "First name).IsNullable(false);
type.AddField("lastName", p => p.LastName, "Last name).IsNullable(false);