FDDB120: Constant key conflicts with computed attribute

Field	Value
Code	FDDB120
Severity	Error

Message

Property '{0}' is a constant key but also has [Computed] — these are mutually exclusive

Description

A key property detected as a constant key (via expression-body or read-only auto-property syntax) cannot also have a [Computed] attribute. Constant keys return a fixed compile-time value, while computed keys combine multiple source properties at runtime. These concepts are mutually exclusive.

When this diagnostic fires, code generation is halted for the affected entity.

Example

The following code triggers this diagnostic:

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

    [SortKey]
    [DynamoDbAttribute("sk")]
    [Computed("Type", "Status", Separator = "#")]
    public string Sk => "PROFILE";  // Constant + Computed = conflict
}

Fix

Remove either the constant value or the [Computed] attribute:

// Option 1: Use constant key (no [Computed])
[SortKey]
[DynamoDbAttribute("sk")]
public string Sk => "PROFILE";

// Option 2: Use computed key (no constant value)
[SortKey]
[DynamoDbAttribute("sk")]
[Computed("Type", "Status", Separator = "#")]
public string Sk { get; set; } = string.Empty;