DynamoDBContext DeleteAsync by key fails

[BryanCrotaz]

Describe the bug

The data table

   "WebsocketConnectionsTable": {
      "Type" : "AWS::DynamoDB::Table",
      "Properties" : {
          "AttributeDefinitions" : [ 
              {
                "AttributeName" : "conn",
                "AttributeType" : "S"
              }
          ],
          "BillingMode" : "PAY_PER_REQUEST",
          "ContributorInsightsSpecification" : {
            "Enabled" : false
          },
          "DeletionProtectionEnabled" : true,
          "GlobalSecondaryIndexes" : [
          ],
          "KeySchema" : [ 
            {
              "AttributeName" : "conn",
              "KeyType" : "HASH"
            }
          ],
          "TableClass" : "STANDARD",
          "TableName" : { 
            "Fn::Join" : [ 
              "-", 
              [ 
                "my-app",            
                { 
                  "Ref" : "StageNameParameter" 
                }, 
                "websocket-auth-table" 
              ] 
            ] 
          },
          "Tags" : [ ]
        }
    }

// the model
    [DynamoDBTable("websocket-auth-table")]
    public class WebsocketConnectionDB
    {
        public WebsocketConnectionDB()
        {
            ConnectionId = "";
            UserId = "";
        }

        [DynamoDBHashKey("conn")]
        public string ConnectionId { get; set; }

        [DynamoDBProperty("user")]
        public string UserId { get; set; }

        [DynamoDBProperty("connected")]
        public Int64 ConnectedAsNumber
        {
            get
            {
                return new DateTimeOffset(Connected).ToUnixTimeSeconds();
            }
            set
            {
                Connected = DateTimeOffset.FromUnixTimeSeconds(value).DateTime;
            }
        }

        [DynamoDBIgnore]
        public DateTime Connected { get; set; }
    }

The code - delete a row based on the hash

    public Task Delete(string id)
    {
               var operationConfig = new DynamoDBOperationConfig()
        {
            TableNamePrefix = this.tableNamePrefix
        };
        return dynamoContext.DeleteAsync<string>(id, operationConfig);
    }

fail    System.InvalidOperationException: Type System.String is unsupported, it cannot be instantiated   
at Amazon.DynamoDBv2.DataModel.StorageConfig..ctor(ITypeInfo targetTypeInfo)   
at Amazon.DynamoDBv2.DataModel.ItemStorageConfig..ctor(ITypeInfo targetTypeInfo)   
at Amazon.DynamoDBv2.DataModel.ItemStorageConfigCache.CreateStorageConfig(Type baseType, String actualTableName)   
at Amazon.DynamoDBv2.DataModel.ItemStorageConfigCache.GetConfig(Type type, DynamoDBFlatConfig flatConfig, Boolean conversionOnly)   
at Amazon.DynamoDBv2.DataModel.ItemStorageConfigCache.GetConfig[T](DynamoDBFlatConfig flatConfig, Boolean conversionOnly)   
at Amazon.DynamoDBv2.DataModel.DynamoDBContext.DeleteHelperAsync[T](Object hashKey, Object rangeKey, DynamoDBOperationConfig operationConfig, CancellationToken cancellationToken)   
at Amazon.DynamoDBv2.DataModel.DynamoDBContext.DeleteAsync[T](Object hashKey, DynamoDBOperationConfig operationConfig, CancellationToken cancellationToken)   
at DynamoRepository`2.Delete(TId id)   
at DisplaySure.WebSockets.WebsocketEntryPoint.HandleDisconnect(APIGatewayProxyRequest request)   
at lambda_method1(Closure , Stream , ILambdaContext , Stream )   
at Amazon.Lambda.RuntimeSupport.Bootstrap.UserCodeLoader.Invoke(Stream lambdaData, ILambdaContext lambdaContext, Stream outStream) in /src/Repo/Libraries/src/Amazon.Lambda.RuntimeSupport/Bootstrap/UserCodeLoader.cs:line 145   
at Amazon.Lambda.RuntimeSupport.HandlerWrapper.<>c__DisplayClass8_0.<GetHandlerWrapper>b__0(InvocationRequest invocation) in /src/Repo/Libraries/src/Amazon.Lambda.RuntimeSupport/Bootstrap/HandlerWrapper.cs:line 55   
at Amazon.Lambda.RuntimeSupport.LambdaBootstrap.InvokeOnceAsync(CancellationToken cancellationToken) in /src/Repo/Libraries/src/Amazon.Lambda.RuntimeSupport/Bootstrap/LambdaBootstrap.cs:line 176 | 2023-05-23T19:08:53.089Z e247f672-d020-428f-b0fb-adc3f4bdcea4 fail System.InvalidOperationException: Type System.String is unsupported, it cannot be instantiated at Amazon.DynamoDBv2.DataModel.StorageConfig..ctor(ITypeInfo targetTypeInfo) 
at Amazon.DynamoDBv2.DataModel.ItemStorageConfig..ctor(ITypeInfo targetTypeInfo) 
at Amazon.DynamoDBv2.DataModel.ItemStorageConfigCache.CreateStorageConfig(Type baseType, String actualTableName) 
at Amazon.DynamoDBv2.DataModel.ItemStorageConfigCache.GetConfig(Type type, DynamoDBFlatConfig flatConfig, Boolean conversionOnly) 
at Amazon.DynamoDBv2.DataModel.ItemStorageConfigCache.GetConfig[T](DynamoDBFlatConfig flatConfig, Boolean conversionOnly) 
at Amazon.DynamoDBv2.DataModel.DynamoDBContext.DeleteHelperAsync[T](Object hashKey, Object rangeKey, DynamoDBOperationConfig operationConfig, CancellationToken cancellationToken)
at Amazon.DynamoDBv2.DataModel.DynamoDBContext.DeleteAsync[T](Object hashKey, DynamoDBOperationConfig operationConfig, CancellationToken cancellationToken) at DynamoRepository`2.Delete(TId id) 
at DisplaySure.WebSockets.WebsocketEntryPoint.HandleDisconnect(APIGatewayProxyRequest request) 
at lambda_method1(Closure , Stream , ILambdaContext , Stream ) 
at Amazon.Lambda.RuntimeSupport.Bootstrap.UserCodeLoader.Invoke(Stream lambdaData, ILambdaContext lambdaContext, Stream outStream) in /src/Repo/Libraries/src/Amazon.Lambda.RuntimeSupport/Bootstrap/UserCodeLoader.cs:line 145 
at Amazon.Lambda.RuntimeSupport.HandlerWrapper.<>c__DisplayClass8_0.<GetHandlerWrapper>b__0(InvocationRequest invocation) in /src/Repo/Libraries/src/Amazon.Lambda.RuntimeSupport/Bootstrap/HandlerWrapper.cs:line 55 
at Amazon.Lambda.RuntimeSupport.LambdaBootstrap.InvokeOnceAsync(CancellationToken cancellationToken) in /src/Repo/Libraries/src/Amazon.Lambda.RuntimeSupport/Bootstrap/LambdaBootstrap.cs:line 176

Expected Behavior

Expected the row with that hash Id to be deleted

Current Behavior

Exception, see above

Reproduction Steps

See above

Possible Solution

No response

Additional Information/Context

No response

AWS .NET SDK and/or Package version used

AWSSDK.DynamoDBv2 3.7.103.8

Targeted .NET Platform

.Net 6

Operating System and version

AWS Lambda

[normj]

@BryanCrotaz You need to change the

return dynamoContext.DeleteAsync<string>(id, operationConfig);

to

return dynamoContext.DeleteAsync<WebsocketConnectionDB>(id, operationConfig);

The generic parameter is used to identify the type and find the table's metadata.

[BryanCrotaz]

Interesting - that's not what the signature says.

DeleteAsync<TId>(TId id ...

That implies that the type is the type of the hash key. The other overload is

DeleteAsync<TModel>(TModel entity ...

[BryanCrotaz]

Your suggestion works but there's no way I would have guessed that from the signature and the docs.

[BryanCrotaz]

Docs I used: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DotNetDynamoDBContext.html

[normj]

In all of the methods the generic parameter is the type of the entity you are working with. Otherwise the library has no context where you are deleting that string from.

I agree the nDoc for that parameter could be a lot more clear. I'm going to turn this into a feature request to update the generic parameter documentation in the code.