In GraphQL, scalar types are used to represent simple, indivisible values. They form the foundation of any GraphQL schema and are essential in defining the structure of data responses. When a GraphQL query is executed, the resulting data is returned in a tree-like structure, where scalar types appear as the leaf nodes—values that do not contain subfields or further nesting.
What Are Scalar Types?
Scalar types are atomic data types that represent a single value. Unlike objects or arrays, scalar types don’t contain other fields or data structures. They are used to define the basic data units in your GraphQL schema and represent the simplest data that can be returned from a query.
In a GraphQL schema, scalar types are used to declare the return types of fields. For example, a name field on a User type might return a String scalar, while an age field would return an Int.
Common Built-in Scalar Types
GraphQL includes several built-in scalar types:
Int
Represents a 32-bit signed integer.
Example: 55
Float
Represents a double-precision floating-point number.
Example: 15.6
String
Represents a sequence of characters.
Example: "program"
Boolean
Represents a true or false value.
Example: true or false
ID
Represents a unique identifier, often used to fetch or reference specific objects. Although it’s serialized as a string, it signifies a unique key.
Example: userID = 1001