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Definition

directive @openfed__subscriptionFilter(condition: openfed__SubscriptionFilterCondition!) on FIELD_DEFINITION

scalar openfed__SubscriptionFilterValue

input openfed__SubscriptionFieldCondition {
    fieldPath: String!
    values: [openfed__SubscriptionFilterValue]!
}

input openfed__SubscriptionFilterCondition {
    AND: [openfed__SubscriptionFilterCondition!]
    IN: openfed__SubscriptionFieldCondition
    NOT: openfed__SubscriptionFilterCondition
    OR: [openfed__SubscriptionFilterCondition!]
}

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Overview

The @openfed__subscriptionFilter directive declares that a field definition can be filtered by filter conditions. The directive can only be applied to EDG subscriptions.

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Arguments

Argument NameArgument Type
conditionopenfed__SubscriptionFilterCondition!
The condition argument requires an object representing the filter condition. This object can be nested to express OR, AND, and NOT conditions. Currently, only the IN comparison operator is supported. This operator can be used to validate if a value is inside a list.

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Supported return types

@openfed__subscriptionFilter works on subscription fields whose return type is:
  • An object type.
  • A union type. The fieldPath must resolve on every accessible union member. If any member is missing the path or resolves to a non-leaf type, composition fails with an error naming the offending member.
  • An interface type. The same rule applies to every accessible concrete implementer.
Members and implementers marked @inaccessible are skipped before validation. The filter runs against the event payload by field name, so the static return type does not affect runtime evaluation. The condition is validated once per concrete type at composition time and emitted as a single configuration in the router.

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Union example

type EntityUpdated @key(fields: "id code", resolvable: false) {
    id: ID! @external
    code: String! @external
}

type EntityDeleted @key(fields: "id code", resolvable: false) {
    id: ID! @external
    code: String! @external
}

union EntityEvent = EntityUpdated | EntityDeleted

type Subscription {
    onEntityEvent(code: String!): EntityEvent!
        @edfs__kafkaSubscribe(topics: ["entity:event"], providerId: "kafka")
        @openfed__subscriptionFilter(condition: {
            IN: { fieldPath: "code", values: ["{{ args.code }}"] }
        })
}
The router checks code on every incoming event payload regardless of __typename. Events whose __typename is not a member of the union surface an INVALID_GRAPHQL error to the subscriber instead of being delivered.