How to pass variables to query?
A GraphQL operation can be parameterized with variables, maximizing reuse, and avoiding costly string building in clients at runtime.
Operation Name:
Declare $variableName as one of the variables accepted by the query
Use the $variableName in the query
Pass variableName: value in the separate, transport-specific (usually JSON) variables dictionary
Values for those variables are provided to a GraphQL service as part of a request so they may be substituted in during execution.
Default values can also be assigned to the variables in the query by adding the default value after the type declaration: