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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.Linq.Expressions;
using System.Threading;
using System.Reflection.Emit;
using System.Collections;
using System.Collections.Specialized;
namespace GenerationExpressionGroupBy
{
class Pet
{
public string Name { get; set; }
public double Age { get; set; }
}
static class Program
{
static void Main(string[] args)
{
List<Pet> petsList =
new List<Pet>{ new Pet { Name="Bernard", Age=8.3 },
new Pet { Name="Boots", Age=4.9 },
new Pet { Name="Boots", Age=1.5 },
new Pet { Name="Toto", Age=4.3 } };
Type T = typeof(Pet);
Dictionary<string, PropertyInfo> sourceProperties = new Dictionary<string, PropertyInfo>();
sourceProperties.Add("Name", T.GetProperty("Name"));
sourceProperties.Add("Sum(Age)", T.GetProperty("Age"));
IEnumerable<object> PetsListObject = petsList;
IEnumerable<object> Resultat = PetsListObject.AsQueryable().GroupDynamic(sourceProperties) as IEnumerable<object>;
// Je souhaiterai un equivalent
var query = petsList.GroupBy(
pet => pet.Name,
(name, pets) => new
{
Name = name,
Count = pets.Count(),
Min = pets.Min(pet => pet.Age),
Max = pets.Max(pet => pet.Age),
TotalAge = pets.Sum(pet => pet.Age)
});
}
static string testFunction(string table, out string opera)
{
opera = "";
if (table.ToLower().Contains("sum(") || table.ToLower().Contains("min(") || table.ToLower().Contains("lower(") || table.ToLower().Contains("upper(") || table.ToLower().Contains("max(") || table.ToLower().Contains("count(") || table.ToLower().Contains("avg("))
{
int longueur = "sum".Length;
opera = table.Substring(0, longueur);
if (opera.ToLower().Equals("cou"))
{
opera += "nt";
longueur += 2;
}
if (opera.ToLower().Equals("upp") || opera.ToLower().Equals("low"))
{
opera += "er";
longueur += 2;
}
longueur++;
table = table.Substring(longueur, table.Length - (longueur));
table = table.Trim(')');
}
return table;
}
static IQueryable GroupDynamic(this IQueryable source, Dictionary<string, PropertyInfo> selectDictionnary)
{
MethodInfo methode = typeof(PropertyInfo).GetMethod("GetValue", new System.Type[] { typeof(object), typeof(object[]) });
object[] vide = new object[0];
Type dynamicType = LinqRuntimeTypeBuilder.GetDynamicType(selectDictionnary.Values);
ParameterExpression sourceItem = Expression.Parameter(source.ElementType, "clef");
ParameterExpression sourceFunctionItem = Expression.Parameter(typeof(IEnumerable<object>), "cible");
// Genere l'expression dynamique du 2eme argument du group by
IEnumerable<MemberBinding> bindings = dynamicType.GetFields().Select(p => getBinding(p, selectDictionnary, sourceItem, sourceFunctionItem)).OfType<MemberBinding>();
// Compilation de l'expression dynamique
var selector2 = Expression.Lambda(Expression.MemberInit(
Expression.New(dynamicType.GetConstructor(Type.EmptyTypes)), bindings), sourceItem, sourceFunctionItem);
var predicat = selector2.Compile();
// Intregration de l'expression au group by
var query = (source as IEnumerable<object>).GroupBy<Func<object, object>>(
getExpression(typeof(Pet).GetProperty("Age"), sourceItem),
predicat);
/// EXEMPLE DE REQUETE CONTENU DANS LE PREDICAT
//(name, pets) => new
//{
// Name = name,
// Count = pets.Count(),
// Min = pets.Min(pet => pet.Age),
// Max = pets.Max(pet => pet.Age),
// TotalAge = pets.Sum(pet => pet.Age)
//}
return source.Provider.CreateQuery(query);
}
static MemberAssignment getBinding(FieldInfo p, Dictionary<string, PropertyInfo> sourceProperties, ParameterExpression sourceItem, ParameterExpression sourceFunctionItem)
{
string opera;
string val;
foreach (KeyValuePair<string, PropertyInfo> entre in sourceProperties)
{
if ((val = testFunction(entre.Key, out opera)).Equals(p.Name) && !opera.Equals("") && p.Name.Contains(val))
{
return Expression.Bind(p, getExpressionComplexe(opera, sourceProperties[entre.Key], sourceItem, sourceFunctionItem));
}
else if (val.Equals(p.Name) && opera.Equals(""))
return Expression.Bind(p, getExpression(sourceProperties[p.Name], sourceItem));
}
throw new Exception("erreur de references");
}
// Min = pets.Min(pet => pet.Age),
// Max = pets.Max(pet => pet.Age),
private static Expression getExpressionComplexe(string opera, PropertyInfo P, ParameterExpression sourceItem, ParameterExpression sourceFunctionItem)
{
MethodInfo methode = typeof(PropertyInfo).GetMethod("GetValue", new System.Type[] { typeof(object), typeof(object[]) });
object[] vide = new object[0];
Expression E = Expression.Convert(Expression.Call(
Expression.Constant(P),
methode,
sourceItem,
Expression.Constant(vide)), typeof(double));
var lambda = Expression.Lambda<Func<object, double>>(E, sourceItem);
var methodeFunctionGenericsList = typeof(Enumerable).GetMethods().Where(d => d.Name.ToLower().Contains(opera.ToLower()) && d.IsGenericMethod);
var methodeFunctionGeneric = methodeFunctionGenericsList.Where(d => d.GetParameters().Any(param => param.Position == 1 && param.ToString().Contains(P.PropertyType.ToString().Split('.')[1]))).FirstOrDefault();
var methodeFunctionDouble = methodeFunctionGeneric.MakeGenericMethod(new[] { typeof(object) });
Type T = E.Type;
Expression function = Expression.Call(null, methodeFunctionDouble, sourceFunctionItem, lambda);
return function;
}
static Expression getExpression(PropertyInfo P, ParameterExpression sourceItem)
{
MethodInfo methode = typeof(PropertyInfo).GetMethod("GetValue", new System.Type[] { typeof(object), typeof(object[]) });
object[] vide = new object[0];
return Expression.Convert(Expression.Call(
Expression.Constant(P),
methode,
sourceItem,
Expression.Constant(vide)), getType(P));
}
static Type getType(PropertyInfo P)
{
return P.PropertyType;
}
}
static class LinqRuntimeTypeBuilder
{
//private static readonly ILog log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
private static AssemblyName assemblyName = new AssemblyName() { Name = "DynamicLinqTypes" };
private static ModuleBuilder moduleBuilder = null;
private static Dictionary<string, Type> builtTypes = new Dictionary<string, Type>();
static LinqRuntimeTypeBuilder()
{
moduleBuilder = Thread.GetDomain().DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run).DefineDynamicModule(assemblyName.Name);
}
private static string GetTypeKey(Dictionary<string, Type> fields)
{
string key = string.Empty;
foreach (var field in fields)
key += field.Key + ";" + field.Value.Name + ";";
return key;
}
public static Type GetDynamicType(Dictionary<string, Type> fields)
{
if (null == fields)
throw new ArgumentNullException("fields");
if (0 == fields.Count)
throw new ArgumentOutOfRangeException("fields", "fields must have at least 1 field definition");
try
{
Monitor.Enter(builtTypes);
string className = GetTypeKey(fields);
if (builtTypes.ContainsKey(className))
return builtTypes[className];
TypeBuilder typeBuilder = moduleBuilder.DefineType(className, TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.Serializable);
foreach (var field in fields)
typeBuilder.DefineField(field.Key, field.Value, FieldAttributes.Public);
builtTypes[className] = typeBuilder.CreateType();
return builtTypes[className];
}
catch (Exception ex)
{
//log.Error(ex);
throw new Exception("erreur");
}
finally
{
Monitor.Exit(builtTypes);
}
return null;
}
private static string GetTypeKey(IEnumerable<PropertyInfo> fields)
{
return GetTypeKey(fields.ToDictionary(f => f.Name, f => f.PropertyType));
}
public static Type GetDynamicType(IEnumerable<PropertyInfo> fields)
{
return GetDynamicType(fields.ToDictionary(f => f.Name, f => f.PropertyType));
}
}
} |
Generer un group by dynamique grâce à des expression lambda et de la reflexion
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