Newtonsoft.Json.JsonSerializationException(从'System.Data.SqlTypes.SqlDouble'的'Value'获取值时出错)序列化SqlGeography

Question

Newtonsoft.Json.JsonSerializationException(从'System.Data.SqlTypes.SqlDouble'的'Value'获取值时出错)序列化SqlGeography

M.H*_*san 10 c# sql-server json geolocation json.net

我尝试DataTable使用数据库SQL Server 2012中的Newtonsoft.Json版本"Newtonsoft.Json.10.0.3" 将对象序列化为Json.

该表有一个类型为'geography'的列,其中包含类型的实例SqlGeography.

用于生成json的代码:

    public string SerializeToJson()
    {

     var connstring1 ="Data Source=server1;Initial Catalog=database1;user=xxx;password=yyy";
        var sql = "SELECT  * FROM table_1 "; //table_1 has a column of type geography
        using (var c1 = new SqlConnection(connstring1))
        {
            c1.Open();
            var da = new SqlDataAdapter()
            {
                SelectCommand = new SqlCommand(sql, c1)
            };

            DataSet ds1 = new DataSet("table");
            da.Fill(ds1, "table");
            var dt = ds1.Tables[0];

            //serialize to Json

            try
            {
                var options = new JsonSerializerSettings
                {
                    Formatting = Formatting.None
                };
                //this line fire exception for geography type
                var json = JsonConvert.SerializeObject(dt, options);
                return json;
            }
            catch (Exception ex)
            {

                Console.WriteLine(ex);
            }                
        }
    }

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我已经从sql 2012的功能包安装了程序集"Microsoft.SqlServer.Types"

我创建了一个完整的C#程序(独立于sql server安装),使用带有SqlGeography列的数据表来显示问题尝试一下

我收到错误:

Newtonsoft.Json.JsonSerializationException:从'System.Data.SqlTypes.SqlDouble'上的'Value'获取值时出错.--->

System.Data.SqlTypes.SqlNullValueException:数据为空.无法在Null值上调用此方法或属性.在Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(对象目标)的GetValue(Object)处的System.Data.SqlTypes.SqlDouble.get_Value()处

我到达了https://github.com/JamesNK/Newtonsoft.Json/issues/993,但它无能为力.

任何帮助解决问题.

编辑:

基于@dbc注释,我提供了用于生成json的完整源代码.

完整的错误消息是:

Newtonsoft.Json.JsonSerializationException:从'System.Data.SqlTypes.SqlDouble'上的'Value'获取值时出错.--- >> System.Data.SqlTypes.SqlNullValueException:数据为空.无法在Null值上调用此方法或属性.在Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(对象目标)的GetValue(Object)处的System.Data.SqlTypes.SqlDouble.get_Value()处

---内部异常堆栈跟踪结束---在Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(对象目标)

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)在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject的Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer,Object value,JsonContract valueContract,JsonProperty成员,JsonContainerContract containerContract,JsonProperty containerProperty)中的contract,JsonProperty成员,JsonContainerContract collectionContract,JsonProperty containerProperty) (JsonWriter writer,Object value,JsonObjectContract contract,JsonProperty member,JsonContainerContract collectionContract,JsonProperty containerProperty)at Newtonsoft.Json.Serialization.JsonSerializerI 在Newtonsoft.Json.Serialization.JsonSerializerProxy的Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter,Object value,Type objectType)中的nternalWriter.SerializeValue(JsonWriter writer,Object value,JsonContract valueContract,JsonProperty成员,JsonContainerContract containerContract,JsonProperty containerProperty)在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeConver表中的Newtonsoft.Json.Converters.DataTableConverter.WriteJson(JsonWriter writer,Object value,JsonSerializer serializer)的.SerializeInternal(JsonWriter jsonWriter,Object value,Type rootType)(JsonWriter writer,JsonConverter converter,对象值,JsonContract契约,JsonContainerContract collectionContract,JsonProperty containerProperty)

在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter作家,对象的值,JsonContract valueContract,JsonProperty构件,JsonContainerContract containerContract,JsonProperty containerProperty)在Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter,对象的值,类型的objectType)在Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter,Object value,Type objectType)Newtonsoft.Json.JsonConvert.SerializeObjectInternal(Object value,Type type,JsonSerializer jsonSerializer)at Newtonsoft.Json.JsonConvert.SerializeObject(Object value,JsonSerializerSettings settings)在F:\ JsonTester.cs中的JsonTester.SerializeToJson():第104行

EDIT2:

我按@dbc的描述启用跟踪,并获取以下日志:

2017-08-24T19:45:31.941信息开始使用转换器Newtonsoft.Json.Converters.DataTableConverter序列化System.Data.DataTable.路径''.

2017-08-24T19:45:31.972 Info已开始序列化Microsoft.SqlServer.Types.SqlGeography.路径'[0] .f1'.

2017-08-24T19:45:32.003信息开始串行化System.Data.SqlTypes.SqlInt32.Path '[0] .f1.STSrid'.

2017-08-24T19:45:32.003 Info完成序列化System.Data.SqlTypes.SqlInt32.路径'[0] .f1.STSrid'.

2017-08-24T19:45:32.003 Info已开始序列化System.Data.SqlTypes.SqlDouble.路径'[0] .f1.Lat'.

2017-08-24T19:45:32.003 Info完成序列化System.Data.SqlTypes.SqlDouble.路径'[0] .f1.Lat'.

2017-08-24T19:45:32.003 Info已开始序列化System.Data.SqlTypes.SqlDouble.路径'[0] .f1.Long'.

2017-08-24T19:45:32.003 Info完成序列化System.Data.SqlTypes.SqlDouble.路径'[0] .f1.Long'.

2017-08-24T19:45:32.003 Info已开始序列化System.Data.SqlTypes.SqlDouble.路径'[0] .f1.Z'.

2017-08-24T19:45:32.003错误序列化System.Data.SqlTypes.SqlDouble.Error从'System.Data.SqlTypes.SqlDouble'上的'Value'获取值时出错.

2017-08-24T19:45:32.003错误序列化System.Data.DataTable时出错.从'System.Data.SqlTypes.SqlDouble'上的'Value'获取值时出错.

Answer 1

dbc*_*dbc 14

它看起来好像原始类型,例如SqlDouble从System.Data.SqlTypes不能序列外的现成的Json.NET,因为他们没有实现自己的TypeConverter.来自文档:

原始类型

.Net :( TypeConverter可转换为String)
JSON:String

这将需要实现自定义JsonConverter以序列化这些类型.Json.NET有几个内置的转换器,例如KeyValuePairConverter内置的.Net类型,所以这并不罕见.

这一事实SqlBoolean,SqlBinary,SqlDouble等不共享一个公共基类或接口比其他INullable需要一些重复的前瞻性代码:

public static class SqlPrimitiveConverters
{
    public static JsonSerializerSettings AddSqlConverters(this JsonSerializerSettings settings)
    {
        foreach (var converter in converters)
            settings.Converters.Add(converter);
        return settings;
    }

    static readonly JsonConverter[] converters = new JsonConverter[]
    {
        new SqlBinaryConverter(),
        new SqlBooleanConverter(),
        new SqlByteConverter(),
        new SqlDateTimeConverter(),
        new SqlDecimalConverter(),
        new SqlDoubleConverter(),
        new SqlGuidConverter(),
        new SqlInt16Converter(),
        new SqlInt32Converter(),
        new SqlInt64Converter(),
        new SqlMoneyConverter(),
        new SqlSingleConverter(),
        new SqlStringConverter(),
        // TODO: converters for primitives from System.Data.SqlTypes that are classes not structs:
        // SqlBytes, SqlChars, SqlXml
        // Maybe SqlFileStream
    };
}

abstract class SqlPrimitiveConverterBase<T> : JsonConverter where T : struct, INullable, IComparable
{
    protected abstract object GetValue(T sqlValue);

    public override bool CanConvert(Type objectType)
    {
        return typeof(T) == objectType;
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        T sqlValue = (T)value;
        if (sqlValue.IsNull)
            writer.WriteNull();
        else
        {
            serializer.Serialize(writer, GetValue(sqlValue));
        }
    }
}

class SqlBinaryConverter : SqlPrimitiveConverterBase<SqlBinary>
{
    protected override object GetValue(SqlBinary sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlBinary.Null;
        return (SqlBinary)serializer.Deserialize<byte[]>(reader);
    }
}

class SqlBooleanConverter : SqlPrimitiveConverterBase<SqlBoolean>
{
    protected override object GetValue(SqlBoolean sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlBoolean.Null;
        return (SqlBoolean)serializer.Deserialize<bool>(reader);
    }
}

class SqlByteConverter : SqlPrimitiveConverterBase<SqlByte>
{
    protected override object GetValue(SqlByte sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlByte.Null;
        return (SqlByte)serializer.Deserialize<byte>(reader);
    }
}

class SqlDateTimeConverter : SqlPrimitiveConverterBase<SqlDateTime>
{
    protected override object GetValue(SqlDateTime sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlDateTime.Null;
        return (SqlDateTime)serializer.Deserialize<DateTime>(reader);
    }
}

class SqlDecimalConverter : SqlPrimitiveConverterBase<SqlDecimal>
{
    protected override object GetValue(SqlDecimal sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlDecimal.Null;
        return (SqlDecimal)serializer.Deserialize<decimal>(reader);
    }
}

class SqlDoubleConverter : SqlPrimitiveConverterBase<SqlDouble>
{
    protected override object GetValue(SqlDouble sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlDouble.Null;
        return (SqlDouble)serializer.Deserialize<double>(reader);
    }
}

class SqlGuidConverter : SqlPrimitiveConverterBase<SqlGuid>
{
    protected override object GetValue(SqlGuid sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlGuid.Null;
        return (SqlGuid)serializer.Deserialize<Guid>(reader);
    }
}

class SqlInt16Converter : SqlPrimitiveConverterBase<SqlInt16>
{
    protected override object GetValue(SqlInt16 sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlInt16.Null;
        return (SqlInt16)serializer.Deserialize<short>(reader);
    }
}

class SqlInt32Converter : SqlPrimitiveConverterBase<SqlInt32>
{
    protected override object GetValue(SqlInt32 sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlInt32.Null;
        return (SqlInt32)serializer.Deserialize<int>(reader);
    }
}

class SqlInt64Converter : SqlPrimitiveConverterBase<SqlInt64>
{
    protected override object GetValue(SqlInt64 sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlInt64.Null;
        return (SqlInt64)serializer.Deserialize<long>(reader);
    }
}

class SqlMoneyConverter : SqlPrimitiveConverterBase<SqlMoney>
{
    protected override object GetValue(SqlMoney sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlMoney.Null;
        return (SqlMoney)serializer.Deserialize<decimal>(reader);
    }
}

class SqlSingleConverter : SqlPrimitiveConverterBase<SqlSingle>
{
    protected override object GetValue(SqlSingle sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlSingle.Null;
        return (SqlSingle)serializer.Deserialize<float>(reader);
    }
}

class SqlStringConverter : SqlPrimitiveConverterBase<SqlString>
{
    protected override object GetValue(SqlString sqlValue) { return sqlValue.Value; }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return SqlString.Null;
        return (SqlString)serializer.Deserialize<string>(reader);
    }
}

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工作.Net小提琴分叉你自己.

如果需要反序列化由此创建的JSON,则还有两个问题.首先,SqlGeography诸如Lat和的一些属性Long是get-only.您需要创建一个自定义JsonConverter来完全反序列化此类型.

其次,Json.NET无法将具有行值的复杂对象的JSON反序列化为无类型DataTable.因此,如果需要反序列化包含复杂对象(例如序列化SqlGeography)的JSON ,则可以使用以下选项:

创建并反序列化为键入的DataTable.
使用DataTableConverter直接填充预先存在的DataTable与预分配的列,如图所示这里.

反序列DTOs化为如下列表:

public class TableRowDTO
{
    [JsonConverter(typeof(SqlGeographyConverter))]
    public SqlGeography f1 { get; set; }
    public int id { get; set; }
}

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哪里SqlGeographyConverter是根据需要,自定义JsonConverter的SqlGeography.

然后做:

var settings = new JsonSerializerSettings().AddSqlConverters();
var list = JsonConvert.DeserializeObject<List<TableRowDTO>>(jsonString, settings);

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万一有人遇到这个问题，我[已复活]（https://github.com/JamesNK/Newtonsoft.Json/issues/993）可以在GitHub和JNK上重新找到。 (2认同)

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