Custom Operators

FastGQL defines a set of operators that can be used to extend the schema. These operators are defined in the fastgql.graphql file. These operators are used to run filters and queries on the database. By default, FastGQL supports common operators:

• eq - equals
• ne - not equals
• gt - greater than
• lt - less than
• gte - greater than or equal
• lte - less than or equal
• in - in
• nin - not in
• like - like
• ilike - ilike
• isNull - is null
• contains - contains
• notContains - not contains
• overlap - overlap
• containedBy - contained by
• suffix - suffix
• prefix - prefix

Adding Custom Operators

FastGQL allows you to add custom operators to the schema. This can be done by defining a new input type in the fastgql.graphql file, or by adding a new operator to an existing input type, by extending the input type.

# extend our input type to include a custom operator
extend input StringComparator  {
    # The custom operator to use for the comparison.
    myCustomOperator: String
}

We will define our custom operator to always do “1 = 1”

func MyCustomOperator(table exp.AliasedExpression, key string, value interface{}) goqu.Expression {
  return goqu.L("1 = 1")
}

In our serve.go where we define our schema, we will add a resolver for the custom operator.

  cfg := &builders.Config{
        Schema: executableSchema.Schema(),
        Logger: adapters.NewZerologAdapter(log.Logger),
        CustomOperators: map[string]builders.Operator{
            "myCustomOperator": MyCustomOperator,
        },
}

An example of a custom operator can be found here.

Adding FilterInputs for Custom Scalar Types

Similar to how StringComparator is used to filter strings, you can define a custom input type to filter custom scalar types.

# Define a custom scalar type
scalar MyCustomScalar

# Define a custom input type to filter the custom scalar type
input MyCustomScalarComparator {
    eq: MyCustomScalar
    # The custom operator to use for the comparison.
    myCustomOperator: MyCustomScalar
}