private static IQueryable <T> ApplyWhere <T>(this IQueryable <T> source, string propertyName, object propertyValue)
where T : class
{
// 1. Retrieve member access expression
var mba = PropertyAccessorCache <T> .Get(propertyName);
if (mba == null)
{
var ex = new NullReferenceException();
Log.Error(ex, $"Error when trying to get the property, it doesn't exist");
throw ex;
}
// 2. Try converting value to correct type
object value;
try
{
value = Convert.ChangeType(propertyValue, mba.ReturnType);
}
catch (SystemException ex) when(
ex is InvalidCastException ||
ex is FormatException ||
ex is OverflowException ||
ex is ArgumentNullException)
{
Log.Error(ex, $"Error when trying to convert type of property value with type of property");
throw;
}
// 3. Construct expression tree
var eqe = Expression.Equal(
mba.Body,
Expression.Constant(value, mba.ReturnType));
var expression = Expression.Lambda(eqe, mba.Parameters[0]);
// 4. Construct new query
MethodCallExpression resultExpression = Expression.Call(
null,
GetMethodInfo(Queryable.Where, source, (Expression <Func <T, bool> >)null),
new Expression[] { source.Expression, Expression.Quote(expression) });
return(source.Provider.CreateQuery <T>(resultExpression));
}
public static IQueryable <T> Where <T>(this IQueryable <T> source, string propertyName, object propertyValue, out bool success) where T : class
{
success = false;
var mba = PropertyAccessorCache <T> .Get(propertyName);
if (mba == null)
{
return(source);
}
object value;
try
{
value = Convert.ChangeType(propertyValue, mba.ReturnType);
}
catch (SystemException ex) when(ex is InvalidCastException ||
ex is FormatException ||
ex is OverflowException ||
ex is ArgumentNullException)
{
return(source);
}
var eqe = Expression.Equal(mba.Body, Expression.Constant(value, mba.ReturnType));
var queryExpr = Expression.Lambda(eqe, mba.Parameters[0]);
success = true;
var resultExpression = Expression.Call(null,
GetMethodInfo <IQueryable <T>,
Expression <Func <T, bool> >,
IQueryable <T> >(Queryable.Where),
new[] { source.Expression, Expression.Quote(queryExpr) });
return(source.Provider.CreateQuery <T>(resultExpression));
}
/// <summary>
/// Get paging
/// </summary>
/// <returns></returns>
/// created by: ntkien 02.06.2020
public virtual async Task <PagingResult <T> > GetByPaging()
{
List <T> results = null;
int totalCounts = 0;
using (NorthWindContext <T> context = new NorthWindContext <T>())
{
IQueryable <T> query = context.ListBase;
IQueryable <T> resultQuery = context.ListBase;
if (_PagingObject == null)
{
return(null);
}
if (_PagingObject.WhereInfos != null && _PagingObject.WhereInfos.Count > 0)
{
foreach (WhereObject whereObject in _PagingObject.WhereInfos)
{
//ntkien: nếu là toán tử bettween thì sẽ apply where 2 lần
if (whereObject.Operation == ExpressionOperationEnum.Bettween)
{
query = query.ApplyWhere(whereObject.ColumnName, whereObject.Value, whereObject.ColumnType, ExpressionOperationEnum.GreatThanEqual);
query = query.ApplyWhere(whereObject.ColumnName, whereObject.Value2, whereObject.ColumnType, ExpressionOperationEnum.LessThanEqual);
}
else
{
query = query.ApplyWhere(whereObject.ColumnName, whereObject.Value, whereObject.ColumnType, whereObject.Operation);
}
}
}
if (_PagingObject.OrderInfos != null && _PagingObject.OrderInfos.Count > 0)
{
bool isFirst = true;
foreach (OrderByObject orderByObject in _PagingObject.OrderInfos)
{
string sort = orderByObject.SortOperation;
if (!string.IsNullOrWhiteSpace(sort) && sort.Equals("desc", StringComparison.OrdinalIgnoreCase))
{
if (isFirst)
{
query = query.ApplyOrderByDesc(orderByObject.ColumnName);
}
else
{
query = query.ApplyThenByDesc(orderByObject.ColumnName);
isFirst = false;
}
}
else
{
if (isFirst)
{
query = query.ApplyOrderBy(orderByObject.ColumnName);
}
else
{
query = query.ApplyThenBy(orderByObject.ColumnName);
isFirst = false;
}
}
}
}
//ntkien 04.06.2020 lấy tổng số bản ghi
totalCounts = await query.CountAsync();
if (_PagingObject.Skip >= 0)
{
query = query.Skip(_PagingObject.Skip).Take(_PagingObject.Take);
}
//ntkien 04.06.2020 nếu khóa chính ko truyền vào thì lấy theo định dạng EntityName + Id
T t = new T();
var primayKey = Utility.GetPrimaryKeyName(t);
if (string.IsNullOrWhiteSpace(primayKey))
{
primayKey = _PagingObject.PrimaryKey;
if (string.IsNullOrWhiteSpace(primayKey))
{
primayKey = string.Format("{0}Id", t.GetType().Name);
}
}
var x = Expression.Parameter(typeof(T), "x");
var body = Expression.PropertyOrField(x, primayKey);
var lambda = Expression.Lambda <Func <T, Guid> >(body, x);
//ntkien 04.06.2020 lấy ra danh sách id rồi mới lấy ra đầy đủ bản ghi (mục đích dùng để tối ưu)
var ids = await query.Select(lambda).ToListAsync();
if (ids != null && ids.Count > 0)
{
Expression expressions = null;
var mba = PropertyAccessorCache <T> .Get(primayKey);
Expression eqe;
foreach (object id in ids)
{
eqe = Expression.Equal(mba.Body, Expression.Constant(id, mba.ReturnType));
if (expressions == null)
{
expressions = eqe;
}
else
{
expressions = Expression.OrElse(expressions, eqe);
}
}
var expression = Expression.Lambda(expressions, mba.Parameters[0]);
// 4. Construct new query
MethodCallExpression resultExpression = Expression.Call(
null,
Utility.GetMethodInfo(Queryable.Where, resultQuery, (Expression <Func <T, bool> >)null),
new Expression[] { resultQuery.Expression, Expression.Quote(expression) });
resultQuery = resultQuery.Provider.CreateQuery <T>(resultExpression);
if (_PagingObject.OrderInfos != null && _PagingObject.OrderInfos.Count > 0)
{
bool isFirst = true;
foreach (OrderByObject orderByObject in _PagingObject.OrderInfos)
{
string sort = orderByObject.SortOperation;
if (!string.IsNullOrWhiteSpace(sort) && sort.Equals("desc", StringComparison.OrdinalIgnoreCase))
{
if (isFirst)
{
resultQuery = resultQuery.ApplyOrderByDesc(orderByObject.ColumnName);
}
else
{
resultQuery = resultQuery.ApplyThenByDesc(orderByObject.ColumnName);
isFirst = false;
}
}
else
{
if (isFirst)
{
resultQuery = resultQuery.ApplyOrderBy(orderByObject.ColumnName);
}
else
{
resultQuery = resultQuery.ApplyThenBy(orderByObject.ColumnName);
isFirst = false;
}
}
}
}
results = await resultQuery.ToListAsync();
}
}
return(new PagingResult <T>()
{
Data = results, TotalCount = totalCounts
});
}