csharp-sdk-upm/Libs/Newtonsoft.Json.AOT/Converters/DataTableConverter.cs

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2021-03-31 11:22:02 +08:00
#region License
// Copyright (c) 2007 James Newton-King
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
#endregion
#if HAVE_ADO_NET
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using LC.Newtonsoft.Json.Utilities;
using System;
using System.Data;
using LC.Newtonsoft.Json.Serialization;
namespace LC.Newtonsoft.Json.Converters
{
/// <summary>
/// Converts a <see cref="DataTable"/> to and from JSON.
/// </summary>
public class DataTableConverter : JsonConverter
{
/// <summary>
/// Writes the JSON representation of the object.
/// </summary>
/// <param name="writer">The <see cref="JsonWriter"/> to write to.</param>
/// <param name="value">The value.</param>
/// <param name="serializer">The calling serializer.</param>
public override void WriteJson(JsonWriter writer, object? value, JsonSerializer serializer)
{
if (value == null)
{
writer.WriteNull();
return;
}
DataTable table = (DataTable)value;
DefaultContractResolver? resolver = serializer.ContractResolver as DefaultContractResolver;
writer.WriteStartArray();
foreach (DataRow row in table.Rows)
{
writer.WriteStartObject();
foreach (DataColumn column in row.Table.Columns)
{
object columnValue = row[column];
if (serializer.NullValueHandling == NullValueHandling.Ignore && (columnValue == null || columnValue == DBNull.Value))
{
continue;
}
writer.WritePropertyName((resolver != null) ? resolver.GetResolvedPropertyName(column.ColumnName) : column.ColumnName);
serializer.Serialize(writer, columnValue);
}
writer.WriteEndObject();
}
writer.WriteEndArray();
}
/// <summary>
/// Reads the JSON representation of the object.
/// </summary>
/// <param name="reader">The <see cref="JsonReader"/> to read from.</param>
/// <param name="objectType">Type of the object.</param>
/// <param name="existingValue">The existing value of object being read.</param>
/// <param name="serializer">The calling serializer.</param>
/// <returns>The object value.</returns>
public override object? ReadJson(JsonReader reader, Type objectType, object? existingValue, JsonSerializer serializer)
{
if (reader.TokenType == JsonToken.Null)
{
return null;
}
if (!(existingValue is DataTable dt))
{
// handle typed datasets
dt = (objectType == typeof(DataTable))
? new DataTable()
: (DataTable)Activator.CreateInstance(objectType);
}
// DataTable is inside a DataSet
// populate the name from the property name
if (reader.TokenType == JsonToken.PropertyName)
{
dt.TableName = (string)reader.Value!;
reader.ReadAndAssert();
if (reader.TokenType == JsonToken.Null)
{
return dt;
}
}
if (reader.TokenType != JsonToken.StartArray)
{
throw JsonSerializationException.Create(reader, "Unexpected JSON token when reading DataTable. Expected StartArray, got {0}.".FormatWith(CultureInfo.InvariantCulture, reader.TokenType));
}
reader.ReadAndAssert();
while (reader.TokenType != JsonToken.EndArray)
{
CreateRow(reader, dt, serializer);
reader.ReadAndAssert();
}
return dt;
}
private static void CreateRow(JsonReader reader, DataTable dt, JsonSerializer serializer)
{
DataRow dr = dt.NewRow();
reader.ReadAndAssert();
while (reader.TokenType == JsonToken.PropertyName)
{
string columnName = (string)reader.Value!;
reader.ReadAndAssert();
DataColumn column = dt.Columns[columnName];
if (column == null)
{
Type columnType = GetColumnDataType(reader);
column = new DataColumn(columnName, columnType);
dt.Columns.Add(column);
}
if (column.DataType == typeof(DataTable))
{
if (reader.TokenType == JsonToken.StartArray)
{
reader.ReadAndAssert();
}
DataTable nestedDt = new DataTable();
while (reader.TokenType != JsonToken.EndArray)
{
CreateRow(reader, nestedDt, serializer);
reader.ReadAndAssert();
}
dr[columnName] = nestedDt;
}
else if (column.DataType.IsArray && column.DataType != typeof(byte[]))
{
if (reader.TokenType == JsonToken.StartArray)
{
reader.ReadAndAssert();
}
List<object?> o = new List<object?>();
while (reader.TokenType != JsonToken.EndArray)
{
o.Add(reader.Value);
reader.ReadAndAssert();
}
Array destinationArray = Array.CreateInstance(column.DataType.GetElementType(), o.Count);
((IList)o).CopyTo(destinationArray, 0);
dr[columnName] = destinationArray;
}
else
{
object columnValue = (reader.Value != null)
? serializer.Deserialize(reader, column.DataType) ?? DBNull.Value
: DBNull.Value;
dr[columnName] = columnValue;
}
reader.ReadAndAssert();
}
dr.EndEdit();
dt.Rows.Add(dr);
}
private static Type GetColumnDataType(JsonReader reader)
{
JsonToken tokenType = reader.TokenType;
switch (tokenType)
{
case JsonToken.Integer:
case JsonToken.Boolean:
case JsonToken.Float:
case JsonToken.String:
case JsonToken.Date:
case JsonToken.Bytes:
return reader.ValueType!;
case JsonToken.Null:
case JsonToken.Undefined:
case JsonToken.EndArray:
return typeof(string);
case JsonToken.StartArray:
reader.ReadAndAssert();
if (reader.TokenType == JsonToken.StartObject)
{
return typeof(DataTable); // nested datatable
}
Type arrayType = GetColumnDataType(reader);
return arrayType.MakeArrayType();
default:
throw JsonSerializationException.Create(reader, "Unexpected JSON token when reading DataTable: {0}".FormatWith(CultureInfo.InvariantCulture, tokenType));
}
}
/// <summary>
/// Determines whether this instance can convert the specified value type.
/// </summary>
/// <param name="valueType">Type of the value.</param>
/// <returns>
/// <c>true</c> if this instance can convert the specified value type; otherwise, <c>false</c>.
/// </returns>
public override bool CanConvert(Type valueType)
{
return typeof(DataTable).IsAssignableFrom(valueType);
}
}
}
#endif