c# - 将 DynamicTableEntity 转换为 Json

Question

我有一个 MVC 应用程序，我执行一个查询来获取表内容。但是当我尝试将结果返回给客户端时，我得到一个 ExceptionMessage: "Cannot return Binary type for a String typed property."

Controller 代码:

public IEnumerable<DynamicTableEntity> Get(string table)
{
    var storageAccount = CloudStorageAccount.Parse(<StorageConnectionString>);
    CloudTableClient tableClient = storageAccount.CreateCloudTableClient();
    CloudTable table = tableClient.GetTableReference(table);

    TableQuery<DynamicTableEntity> query = new TableQuery<DynamicTableEntity>()
       .Where("")
       .Take(50);

    return table.ExecuteQuery(query);
}

当我执行 Get table 时，我得到 500 Internal Server Error

ExceptionMessage: "The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'."

InnerException:

ExceptionMessage: "Cannot return Binary type for a String typed property."

但是当我调试“Get”函数时，我看到所有数据均按预期接收，这是 Json序列化问题。我尝试使用 CloudTableClient PayloadFormat和DefaultRequestOptions但没有成功。

有什么建议吗？

堆栈跟踪:

{
Message: "An error has occurred."
ExceptionMessage: "The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'."
ExceptionType: "System.InvalidOperationException"
StackTrace: null
InnerException: {
Message: "An error has occurred."
ExceptionMessage: "Error getting value from 'BinaryValue' on 'Microsoft.WindowsAzure.Storage.Table.EntityProperty'."
ExceptionType: "Newtonsoft.Json.JsonSerializationException"
StackTrace: " at Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(Object target) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CalculatePropertyValues(JsonWriter writer, Object value, JsonContainerContract contract, JsonProperty member, JsonProperty property, JsonContract& memberContract, Object& memberValue) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeDictionary(JsonWriter writer, IDictionary values, JsonDictionaryContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IEnumerable values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value, Type objectType) at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value, Type objectType) at Newtonsoft.Json.JsonSerializer.Serialize(JsonWriter jsonWriter, Object value) at System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, Encoding effectiveEncoding) at System.Net.Http.Formatting.JsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, Encoding effectiveEncoding) at System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content) at System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext, CancellationToken cancellationToken) --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter.GetResult() at System.Web.Http.WebHost.HttpControllerHandler.<WriteBufferedResponseContentAsync>d__1b.MoveNext()"
InnerException: {
Message: "An error has occurred."
ExceptionMessage: "Cannot return Binary type for a Boolean typed property."
ExceptionType: "System.InvalidOperationException"
StackTrace: " at Microsoft.WindowsAzure.Storage.Table.EntityProperty.EnforceType(EdmType requestedType) at Microsoft.WindowsAzure.Storage.Table.EntityProperty.get_BinaryValue() at GetBinaryValue(Object ) at Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(Object target)"
}-
}-
}

Answer 1

不幸的是，DynamicTableEntity 和 EntityProperty 当前不可序列化。另一方面，POCO 实体是可序列化的。如果您反序列化为派生自 TableEntity 的对象，那么它应该是开箱即用的可序列化。如果您想要执行真正的异构查询，必须处理存储在单个表中并作为查询结果返回的不同类型，则可以使用 EntityResolver 解析为适当的类型。