Requête LINQ to entities pour DataTable

C'est le MSDN solution recommandée: https://msdn.microsoft.com/en-us/library/bb669096(v=vs. 110).aspx

J'ai mis en œuvre avec succès
(*avec des ajouts mineurs à gérer nullable DateTime.)
comme Suit:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using System.Reflection;
///<summary>
///Converts Entity Type to DataTable
///</summary>
public class ObjectShredder<T>
{
private System.Reflection.FieldInfo[] _fi;
private System.Reflection.PropertyInfo[] _pi;
private System.Collections.Generic.Dictionary<string, int> _ordinalMap;
private System.Type _type;
//ObjectShredder constructor.
public ObjectShredder()
{
_type = typeof(T);
_fi = _type.GetFields();
_pi = _type.GetProperties();
_ordinalMap = new Dictionary<string, int>();
}
///<summary>
///Loads a DataTable from a sequence of objects.
///</summary>
///<param name="source">The sequence of objects to load into the DataTable.</param>
///<param name="table">The input table. The schema of the table must match that 
///the type T.  If the table is null, a new table is created with a schema 
///created from the public properties and fields of the type T.</param>
///<param name="options">Specifies how values from the source sequence will be applied to 
///existing rows in the table.</param>
///<returns>A DataTable created from the source sequence.</returns>
public DataTable Shred(IEnumerable<T> source, DataTable table, LoadOption? options)
{
//Load the table from the scalar sequence if T is a primitive type.
if (typeof(T).IsPrimitive)
{
return ShredPrimitive(source, table, options);
}
//Create a new table if the input table is null.
if (table == null)
{
table = new DataTable(typeof(T).Name);
}
//Initialize the ordinal map and extend the table schema based on type T.
table = ExtendTable(table, typeof(T));
//Enumerate the source sequence and load the object values into rows.
table.BeginLoadData();
using (IEnumerator<T> e = source.GetEnumerator())
{
while (e.MoveNext())
{
if (options != null)
{
table.LoadDataRow(ShredObject(table, e.Current), (LoadOption)options);
}
else
{
table.LoadDataRow(ShredObject(table, e.Current), true);
}
}
}
table.EndLoadData();
//Return the table.
return table;
}
public DataTable ShredPrimitive(IEnumerable<T> source, DataTable table, LoadOption? options)
{
//Create a new table if the input table is null.
if (table == null)
{
table = new DataTable(typeof(T).Name);
}
if (!table.Columns.Contains("Value"))
{
table.Columns.Add("Value", typeof(T));
}
//Enumerate the source sequence and load the scalar values into rows.
table.BeginLoadData();
using (IEnumerator<T> e = source.GetEnumerator())
{
Object[] values = new object[table.Columns.Count];
while (e.MoveNext())
{
values[table.Columns["Value"].Ordinal] = e.Current;
if (options != null)
{
table.LoadDataRow(values, (LoadOption)options);
}
else
{
table.LoadDataRow(values, true);
}
}
}
table.EndLoadData();
//Return the table.
return table;
}
public object[] ShredObject(DataTable table, T instance)
{
FieldInfo[] fi = _fi;
PropertyInfo[] pi = _pi;
if (instance.GetType() != typeof(T))
{
//If the instance is derived from T, extend the table schema
//and get the properties and fields.
ExtendTable(table, instance.GetType());
fi = instance.GetType().GetFields();
pi = instance.GetType().GetProperties();
}
//Add the property and field values of the instance to an array.
Object[] values = new object[table.Columns.Count];
foreach (FieldInfo f in fi)
{
values[_ordinalMap[f.Name]] = f.GetValue(instance);
}
foreach (PropertyInfo p in pi)
{
values[_ordinalMap[p.Name]] = p.GetValue(instance, null);
}
//Return the property and field values of the instance.
return values;
}
public DataTable ExtendTable(DataTable table, Type type)
{
//Extend the table schema if the input table was null or if the value 
//in the sequence is derived from type T.            
foreach (FieldInfo f in type.GetFields())
{
if (!_ordinalMap.ContainsKey(f.Name))
{
//Add the field as a column in the table if it doesn't exist
//already.
DataColumn dc = table.Columns.Contains(f.Name) ? table.Columns[f.Name]
: table.Columns.Add(f.Name, f.FieldType);
//Add the field to the ordinal map.
_ordinalMap.Add(f.Name, dc.Ordinal);
}
}
foreach (PropertyInfo p in type.GetProperties())
{
if (!_ordinalMap.ContainsKey(p.Name))
{
//Add the property as a column in the table if it doesn't exist already.
DataColumn dc = table.Columns[p.Name];
//Added Try Catch to account for Nullable Types  
try
{
dc = table.Columns.Contains(p.Name) ? table.Columns[p.Name]
: table.Columns.Add(p.Name, p.PropertyType);
}
catch (NotSupportedException nsEx)
{
string pType = p.PropertyType.ToString();
dc = pType.Contains("System.DateTime") ? table.Columns.Add(p.Name, typeof(System.DateTime)) : table.Columns.Add(p.Name);
//dc = table.Columns.Add(p.Name); //Modified to above statment in order to accomodate Nullable date Time 
}
//Add the property to the ordinal map.
_ordinalMap.Add(p.Name, dc.Ordinal);
}
}
//Return the table.
return table;
}
}

}

Le (gros) inconvénient de cette solution est qu'il est ** coûteux** et vous devez le personnaliser dans la gestion des erreurs.

OriginalL'auteur DaniDev