Customize field results
A field needs client-provided criteria such as an identifier, filter, or unit.
GraphQL · Class
GraphQLArgument
GraphQL arguments are named inputs declared by fields or directives. They can be optional or required, may have defaults, and must use input types.
How it works
A GraphQL argument is a named input supplied to a field or directive to influence its result or behavior. Its schema definition specifies an input type and may mark the value as required or provide a default.
Syntax
field(argumentName: InputType): ReturnTypeKey points
- Arguments belong to field definitions, and a field may declare none, one, or many.
- A schema gives each argument its own name, such as
uniton a length field. - Schema authors can choose a fallback value for an optional argument.
- Every argument definition declares the input type accepted by that field.
- Clients write argument names alongside their values rather than relying on positional slots.
Common mistakes
- Arguments are not positional; changing their order does not change their meaning.
- An operation cannot pass an argument that the target field or directive has not declared.
- Do not assume an omitted argument is invalid; optional arguments may be absent.
Example: Named field arguments
query GetHuman($id: ID!, $size: Int) {
human(id: $id) {
name
profilePic(size: $size)
}
}A query supplies named arguments directly and factors dynamic values into variables.
When to use it
Provide defaults
A schema offers a sensible behavior when callers omit a nonessential option.
Use variables
A query needs dynamic values supplied separately from its document.
Interview questions
QWhat is a GraphQL argument?
Arguments are named inputs attached to fields or directives. A field can define zero or more of them, and each argument can alter the field's returned result.
Follow-up: Why are named arguments useful? They let a field accept several values without depending on positional ordering, so adding or rearranging arguments remains clearer and less error-prone.
QHow do required, optional, and defaulted arguments differ?
An argument is required when its type is non-null; otherwise it is optional. An optional argument may define a default value that is used when the client omits it.
Follow-up: What happens when a non-null argument is omitted? Validation rejects the operation because the required argument has no supplied value.
QHow are argument values supplied in a query?
Arguments must use input types. GraphQL fields may receive arguments at every nesting level, and variables provide a separate dictionary for dynamic argument values.
Follow-up: Why use variables instead of embedding dynamic values? Variables separate changing data from the query document and can be supplied through the transport request.
Related
Schemas and TypesArgumentsFieldsInput Object typesQueriesVariablesExecution