FDDB0020: EnableDynamicFields requires partial class

Field	Value
Code	FDDB0020
Severity	Error

Message

Class '{0}' is marked with [EnableDynamicFields] but is not declared as 'partial'. The source generator needs to add a DynamicFields property to the class.

Description

Classes marked with [EnableDynamicFields] must be declared as partial to allow the source generator to add the DynamicFields property.

The [EnableDynamicFields] attribute instructs the source generator to add a DynamicFields property that captures DynamoDB attributes not explicitly mapped to entity properties. Without the partial modifier, the generator cannot add this property.

Example

The following code triggers this diagnostic:

[DynamoDbTable("nodes")]
[EnableDynamicFields]
public class TreeNode  // Missing 'partial' keyword
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    public string Pk { get; set; } = string.Empty;

    [SortKey]
    [DynamoDbAttribute("sk")]
    public string Sk { get; set; } = string.Empty;
}

Fix

The corrected version:

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

    [SortKey]
    [DynamoDbAttribute("sk")]
    public string Sk { get; set; } = string.Empty;
}