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DISC002: DiscriminatorValue or DiscriminatorPattern without DiscriminatorProperty

FieldValue
CodeDISC002
SeverityError

Message​

Entity '{0}' has DiscriminatorValue or DiscriminatorPattern specified but DiscriminatorProperty is missing. Specify DiscriminatorProperty to indicate which attribute contains the discriminator.

Description​

DiscriminatorProperty must be specified when using DiscriminatorValue or DiscriminatorPattern. It tells the source generator which DynamoDB attribute contains the discriminator value used to distinguish entity types in a shared GSI.

Without DiscriminatorProperty, the generator cannot produce the correct MatchesEntity filter logic because it does not know which attribute to inspect when determining whether a given item belongs to this entity type.

Example​

The following code triggers this diagnostic:

[DynamoDbTable("shared-table", IsDefault = true)]
public partial class Order
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    public string Pk { get; set; } = string.Empty;

    [GsiPartitionKey("gsi1",
        DiscriminatorValue = "ORDER")]
    [DynamoDbAttribute("gsi1pk")]
    public string Gsi1Pk { get; set; } = string.Empty;
}

Fix​

The corrected version:

[DynamoDbTable("shared-table", IsDefault = true)]
public partial class Order
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    public string Pk { get; set; } = string.Empty;

    [GsiPartitionKey("gsi1",
        DiscriminatorProperty = "entityType",
        DiscriminatorValue = "ORDER")]
    [DynamoDbAttribute("gsi1pk")]
    public string Gsi1Pk { get; set; } = string.Empty;
}