public static IQueryable SelectByInterface <T>(this IQueryable <T> source, Type interfaceType, bool includeTypeName = true)
{
var properties = interfaceType.GetPublicProperties().Where(each => each.PropertyType.IsSimple()).ToList();
var objectFields = properties.Select(each => each.Name).ToList();
if (includeTypeName)
{
objectFields.Add("_Type");
}
var sourceType = source.GetType().GetGenericArguments().First();
var param = Expression.Parameter(sourceType);
var expressions = new List <MemberBinding>();
lock (RuntimeTypes) {
if (!RuntimeTypes.ContainsKey(interfaceType))
{
var runtimeType = new RuntimeObjectBuilder().CreateNewObject(interfaceType, interfaceType, objectFields.ToArray()).GetType();
RuntimeTypes.Add(interfaceType, runtimeType);
}
var instance = Activator.CreateInstance(RuntimeTypes[interfaceType]);
var type = instance.GetType();
if (includeTypeName)
{
var typeProperty = type.GetProperty("_Type");
expressions.Add(Expression.Bind(typeProperty, Expression.Constant(typeof(T).Name)));
}
foreach (var property in instance.GetType().GetProperties())
{
if (property.Name.StartsWith("_"))
{
continue;
}
expressions.Add(Expression.Bind(property, Expression.PropertyOrField(param, property.Name)));
}
var init = Expression.MemberInit(Expression.New(instance.GetType()), expressions.ToArray());
var func = typeof(Func <,>).MakeGenericType(typeof(T), type);
var lambdaMethods = typeof(Expression).GetMethods().Where(each => each.Name == "Lambda");
var expression = lambdaMethods.First().MakeGenericMethod(func).Invoke(null, new object[] { init, new[] { param } }) as Expression;
//var expression = Expression.Lambda<Func<T, I>>(init, param);
var methods = typeof(Queryable).GetMethods().Where(each => each.Name == "Select").ToList();
var method = methods.FirstOrDefault().MakeGenericMethod(typeof(T), type);
return(method.Invoke(null, new object[] { source, expression }) as IQueryable);
}
}
public static IQueryable <BaseRuntimeObject> DynamicSelect <T, G>(this IQueryable <IGrouping <G, T> > source, string groupName, params string[] propertyNames)
{
var objectFields = new List <string>(propertyNames);
objectFields.Add(groupName);
var sourceType = source.GetType().GetGenericArguments().First();
var param = Expression.Parameter(sourceType);
var expressions = new List <MemberBinding>();
var instance = new RuntimeObjectBuilder().CreateNewObject(typeof(T), null, objectFields.ToArray());
var type = instance.GetType();
var groupProperty = type.GetProperty(groupName);
foreach (var propertyName in propertyNames)
{
var property = type.GetProperty(propertyName);
var sumMethod = typeof(Enumerable).GetMethods()
.FirstOrDefault(x => x.Name == "Sum" && x.ContainsGenericParameters && x.ReturnType == property.PropertyType);
if (sumMethod != null)
{
var eachEntity = Expression.Parameter(typeof(T), "each");
var propertyAccess = Expression.Property(eachEntity, propertyName);
var lambda = Expression.Lambda(propertyAccess, eachEntity);
var sumExpression = Expression.Call(sumMethod.MakeGenericMethod(typeof(T)), param, lambda);
expressions.Add(Expression.Bind(property, sumExpression));
}
else
{
expressions.Add(Expression.Bind(property, Expression.PropertyOrField(param, propertyName)));
}
}
expressions.Add(Expression.Bind(groupProperty, Expression.PropertyOrField(param, "Key")));
var init = Expression.MemberInit(Expression.New(instance.GetType()), expressions.ToArray());
var expression = Expression.Lambda <Func <IGrouping <G, T>, BaseRuntimeObject> >(init, param);
return(source.Select(expression));
}
