PROJ002: Projection property type mismatch

Field	Value
Code	PROJ002
Severity	Error

Message

Property '{0}' type '{1}' on projection '{2}' does not match source entity type '{3}'

Description

Projection property types must match the corresponding source entity property types. When a projection declares a property that exists on the source entity, the type of that property must be identical.

This diagnostic is emitted when a projection property has a different type than the matching property on the source entity. Type mismatches prevent the source generator from producing correct mapping code between the DynamoDB item and the projection model.

Example

The following code triggers this diagnostic:

[DynamoDbTable("Orders")]
public partial class Order
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    public string Pk { get; set; } = string.Empty;

    [DynamoDbAttribute("totalAmount")]
    public decimal TotalAmount { get; set; }
}

[DynamoDbProjection(typeof(Order))]
public partial class OrderSummary
{
    // PROJ002: type 'string' does not match source type 'decimal'
    [DynamoDbAttribute("totalAmount")]
    public string TotalAmount { get; set; } = string.Empty;
}

Fix

The corrected version:

[DynamoDbTable("Orders")]
public partial class Order
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    public string Pk { get; set; } = string.Empty;

    [DynamoDbAttribute("totalAmount")]
    public decimal TotalAmount { get; set; }
}

[DynamoDbProjection(typeof(Order))]
public partial class OrderSummary
{
    [DynamoDbAttribute("totalAmount")]
    public decimal TotalAmount { get; set; }
}