C# 无法在Unity中查询或扫描DynamoDB

TLDR:无法从QueryAsync或ScanAsync创建AsyncSearch对象，除非在AWS库的深处遇到异常

我正在Unity中开发一个在线游戏，希望与DynamoDB同步数据。当我只有一张包含玩家数据的表格时，这非常有效。我只需要使用“DBContext.LoadAsync（id，callback）；”就可以了，而且它工作得非常完美。使用“SaveAsync”保存也可以

现在我介绍了更多的表，我需要执行扫描和查询。出于测试目的，我给了我的Unity应用程序可能拥有的所有权利（我在IAM中使用了“dynamodb:*”和“Resource”：[“*”]）

我用不同的参数尝试了ScanAsync、QueryAsync和FromQueryAsync的所有可能版本，但我总是遇到错误

简单示例：我想下载（我所在大学的）所有系：

如果我想基于二级索引进行查询，情况会更糟。为此，我需要在哈希和范围键的条件之后附加一个dynamodboOperationConfig，如下所示：

var queryConfig = new DynamoDBOperationConfig() { IndexName = "PlayerIndex" };
AsyncSearch<POIVisit> query = AWSManager.Instance.DBContext.QueryAsync<POIVisit>(poiType, QueryOperator.Equal, PlayerID, queryConfig);

我的Unity版本是5.6.3f1。我尝试了AWSSDK.DynamoDBv2.3.3.4.18和旧的AWSSDK.DynamoDBv2.3.3.4.14 Unity软件包，其中包含直接从Amazon下载的AWS SDK

---

如果有人暗示我可能做错了什么，我会非常感激，谢谢

在创建查询之前，您需要构建一个请求对象。我从未使用过团结，但它应该是这样的

var request = new QueryRequest();
request.TableName = "YourTable";   
request.KeyConditions = new Dictionary<string, Condition>()
{
    { 
        "YourId",  new Condition()
        { 
            ComparisonOperator = "EQ",
            AttributeValueList = new List<AttributeValue>()
            {
                new AttributeValue { S = YourId }
            }
        }
    }
};

client.QueryAsync(request,(result));

var request=newqueryrequest（）；
request.TableName=“YourTable”；
request.KeyConditions=新字典（）
{
{ 
“YourId”，新条件（）
{ 
ComparisonOperator=“EQ”，
AttributeValueList=新列表（）
{
新属性值{S=YourId}
}
}
}
};
QueryAsync（请求，（结果））；

---

具体来说，您似乎没有将您的密钥条件作为请求的一部分，这是必需的。

谢谢。不幸的是，在Unity中，不支持创建这样的请求。没有以QueryRequest作为参数的QuerySync函数。相反，存在QuerySync，其中T是一个具有DynamoDB表属性的类。此类是表项的表示形式，表名、哈希和范围键是使用属性定义的。我应该能够通过传递散列键的值来使用该函数。这适用于加载和保存，但查询和扫描不起作用。对于扫描，无论如何都不需要键。我以为这就是扫描的全部意义…对不起，这没有多大帮助。您有权访问任何DynamoDB Unity文档吗？我找不到。如果这有什么帮助的话，我就拿它做例子，也许是AWS论坛上的一个例子。

ArgumentNullException: Argument cannot be null.
Parameter name: key
System.Collections.Generic.Dictionary`2[System.Type,Amazon.Runtime.IExceptionHandler].TryGetValue (System.Type key, IExceptionHandler& value) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Collections.Generic/Dictionary.cs:588)
Amazon.Runtime.Internal.ErrorHandler.ProcessException (IExecutionContext executionContext, System.Exception exception) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Core/Amazon.Runtime/Pipeline/ErrorHandler/ErrorHandler.cs:202)
Amazon.Runtime.Internal.ErrorHandler.InvokeSync (IExecutionContext executionContext) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Core/Amazon.Runtime/Pipeline/ErrorHandler/ErrorHandler.cs:78)
Amazon.Runtime.Internal.PipelineHandler.InvokeSync (IExecutionContext executionContext) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Core/Amazon.Runtime/Pipeline/PipelineHandler.cs:57)
Amazon.Runtime.Internal.CallbackHandler.InvokeSync (IExecutionContext executionContext) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Core/Amazon.Runtime/Pipeline/Handlers/CallbackHandler.cs:45)
Amazon.Runtime.Internal.PipelineHandler.InvokeSync (IExecutionContext executionContext) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Core/Amazon.Runtime/Pipeline/PipelineHandler.cs:57)
Amazon.Runtime.Internal.Signer.InvokeSync (IExecutionContext executionContext) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Core/Amazon.Runtime/Pipeline/Handlers/Signer.cs:38)
Amazon.Runtime.Internal.PipelineHandler.InvokeSync (IExecutionContext executionContext) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Core/Amazon.Runtime/Pipeline/PipelineHandler.cs:57)
Amazon.Runtime.Internal.CredentialsRetriever.InvokeSync (IExecutionContext executionContext) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Core/Amazon.Runtime/Pipeline/Handlers/CredentialsRetriever.cs:72)
Amazon.Runtime.Internal.PipelineHandler.InvokeSync (IExecutionContext executionContext) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Core/Amazon.Runtime/Pipeline/PipelineHandler.cs:57)
Amazon.Runtime.Internal.RetryHandler.InvokeSync (IExecutionContext executionContext) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Core/Amazon.Runtime/Pipeline/RetryHandler/RetryHandler.cs:74)

var queryConfig = new DynamoDBOperationConfig() { IndexName = "PlayerIndex" };
AsyncSearch<POIVisit> query = AWSManager.Instance.DBContext.QueryAsync<POIVisit>(poiType, QueryOperator.Equal, PlayerID, queryConfig);

InvalidCastException: Cannot cast from source type to destination type.
Amazon.DynamoDBv2.Converter`1[T].TryTo (System.Object value, Amazon.DynamoDBv2.DocumentModel.Primitive& p) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Services/DynamoDBv2/Custom/Conversion/DynamoDBEntryConversion.cs:630)
…
Amazon.DynamoDBv2.DataModel.DynamoDBContext.QueryAsync[POIVisit] (System.Object hashKeyValue, QueryOperator op, System.Object[] values) (at E:/JenkinsWorkspaces/v3-trebuchet-release/AWSDotNetPublic/sdk/src/Services/DynamoDBv2/Custom/DataModel/_unity/Context.Async.cs:550)
DBManager.RetrievePlayerVisits (System.String poiType, UnityEngine.Events.UnityAction`1 callback) (at Assets/Scripts/Managers/DBManager.cs:359)

var request = new QueryRequest();
request.TableName = "YourTable";   
request.KeyConditions = new Dictionary<string, Condition>()
{
    { 
        "YourId",  new Condition()
        { 
            ComparisonOperator = "EQ",
            AttributeValueList = new List<AttributeValue>()
            {
                new AttributeValue { S = YourId }
            }
        }
    }
};

client.QueryAsync(request,(result));