What is it

Data passed to schema's resolver/field

• Argument values can be hardcoded or pass via GraphQL input variable

# schema definition
type Query {
  resources: [Resource!]!
  resource(format: DataFormat!): Resource!
}

• resources field returns array of Resource type data
  • Corresponding resolver does not take an input
• resource field returns object of Resource type after taking in format argument
  • Resolver consumes the input value and executes function

Difference: input vs no input

For resource field, argument/input allows user to narrow down the data returned.

For resources field, the field is an all-or-nothing return as we can only get back predefined results.

# schema definition field
resource(format: DataFormat!): Resource!

• resource would be the field name
• format would be the argument name
• DataFormat would be the argument's data type
  • required by !, makes it non-nullable argument
  • will result in error when other types are passed
• Resource would be the return data type on the field
  • required by !, makes it non-nullable

Client

# client query
query GetResource {
  resource(format: "jpeg") {
    id
    data
  }
}

The argument on the client query and the schema can be named anything.

• It does not have to match the field name on the schema

For example, when we are passing argument id,