您对我们如何使用System.Text.Json.JsonSerializer serialize DataSet,DataTable如何有任何建议?当前它抛出此异常:'检测到不支持的可能的对象循环。这可能是由于循环造成的,或者可能是由于对象深度大于允许的最大深度64。'
当前不内置对DataSet
中的DataTable
和System.Text.Json
之类的类型的支持(自.NET Core 3.1开始)。为了能够序列化此类类型,您将需要为所需的类型实现自己的JsonConverter<T>
并将其注册在JsonSerializerOptions
中。为您要的特定类型编写一个用于序列化的代码应该很容易。
这是一个应该用于序列化的示例(省略了反序列化组件):
public class DataTableConverter : JsonConverter<DataTable>
{
public override DataTable Read(ref Utf8JsonReader reader, Type typeToConvert,
JsonSerializerOptions options)
{
throw new NotImplementedException();
}
public override void Write(Utf8JsonWriter writer, DataTable value,
JsonSerializerOptions options)
{
writer.WriteStartArray();
foreach (DataRow row in value.Rows)
{
writer.WriteStartObject();
foreach (DataColumn column in row.Table.Columns)
{
object columnValue = row[column];
// If necessary:
if (options.IgnoreNullValues)
{
// Do null checks on the values here and skip writing.
}
writer.WritePropertyName(column.ColumnName);
JsonSerializer.Serialize(writer, columnValue, options);
}
writer.WriteEndObject();
}
writer.WriteEndArray();
}
}
public class DataSetConverter : JsonConverter<DataSet>
{
public override DataSet Read(ref Utf8JsonReader reader, Type typeToConvert,
JsonSerializerOptions options)
{
throw new NotImplementedException();
}
public override void Write(Utf8JsonWriter writer, DataSet value,
JsonSerializerOptions options)
{
writer.WriteStartObject();
foreach (DataTable table in value.Tables)
{
writer.WritePropertyName(table.TableName);
JsonSerializer.Serialize(writer, table, options);
}
writer.WriteEndObject();
}
}
private static void DataSet_Serialization_WithSystemTextJson()
{
var options = new JsonSerializerOptions()
{
Converters = { new DataTableConverter(), new DataSetConverter() }
};
(DataTable table, DataSet dataSet) = GetDataSetAndTable();
string jsonDataTable = JsonSerializer.Serialize(table, options);
// [{"id":0,"item":"item 0"},{"id":1,"item":"item 1"}]
Console.WriteLine(jsonDataTable);
string jsonDataSet = JsonSerializer.Serialize(dataSet, options);
// {"Table1":[{"id":0,"item":"item 0"},{"id":1,"item":"item 1"}]}
Console.WriteLine(jsonDataSet);
// Local function to create a sample DataTable and DataSet
(DataTable, DataSet) GetDataSetAndTable()
{
dataSet = new DataSet("dataSet");
table = new DataTable();
DataColumn idColumn = new DataColumn("id", typeof(int))
{
AutoIncrement = true
};
DataColumn itemColumn = new DataColumn("item");
table.Columns.Add(idColumn);
table.Columns.Add(itemColumn);
dataSet.Tables.Add(table);
for (int i = 0; i < 2; i++)
{
DataRow newRow = table.NewRow();
newRow["item"] = "item " + i;
table.Rows.Add(newRow);
}
dataSet.AcceptChanges();
return (table, dataSet);
}
}
此文档可能会提供更多指导:https://docs.microsoft.com/en-us/dotnet/standard/serialization/system-text-json-converters-how-to