DYNDB018: Invalid key format syntax

Field	Value
Code	DYNDB018
Severity	Error

Message

Key format '{0}' on property '{1}' contains invalid syntax or placeholders

Description

Key formats must use valid placeholder syntax like 0, 1, etc. and cannot contain reserved characters. The source generator parses key formats to generate key construction methods, and invalid syntax prevents correct code generation.

Example

The following code triggers this diagnostic:

[DynamoDbTable("Events")]
public partial class Event
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    [Computed("Year", "Month", Separator = "#", Format = "{invalid}")]
    public string Pk { get; set; } = string.Empty;

    [Extracted("Pk", 0)]
    public int Year { get; set; }

    [Extracted("Pk", 1)]
    public int Month { get; set; }
}

Fix

The corrected version:

[DynamoDbTable("Events")]
public partial class Event
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    [Computed("Year", "Month", Separator = "#")]
    public string Pk { get; set; } = string.Empty;

    [Extracted("Pk", 0)]
    public int Year { get; set; }

    [Extracted("Pk", 1)]
    public int Month { get; set; }
}