public static Expression CovertToExpression(Type type, QueryExpression qExpression)
{
if (string.IsNullOrEmpty(qExpression.PropertyName))
{
return(null);
}
ParameterExpression param = Expression.Parameter(type, "c");
Expression condition = null;
// Merege Expression
List <QueryExpression> list = new List <QueryExpression>();
list.Add(qExpression);
QueryExpression rE = qExpression.RelatedExpression;
while (rE != null)
{
list.Add(rE);
rE = rE.RelatedExpression;
}
for (int i = list.Count - 1; i >= 0; i--)
{
QueryExpression currentExpression = list[i];
if (string.IsNullOrEmpty(currentExpression.PropertyName))
{
continue;
}
Expression left = GetLeft(param, currentExpression.PropertyName);
Type propertyType = left.Type;
Expression right = null;
if (list[i].RightPropertyValue != null)
{
right = Expression.Constant(list[i].RightPropertyValue);
}
else
{
object cValue = TryConvertValue(propertyType, currentExpression.PropertyValue);
right = Expression.Constant(cValue, propertyType);
}
Expression filter = QueryExpressionHelper.MergeExpression(currentExpression.Operation, left, right);
if (condition == null)
{
condition = filter;
}
else if (currentExpression.RelatedType == QueryExpression.RelationType.And)
{
condition = Expression.And(condition, filter);
}
else
{
condition = Expression.Or(condition, filter);
}
}
if (condition == QueryExpressionHelper.EmptyExpression)
{
return(null);
}
return(Expression.Lambda(condition, param));
}
