private static Expression GetCompareExpression(FilterInstruction pInstruction, Expression property)
{
if (!pInstruction.MatchExact)
{
if (pInstruction.Value != null && pInstruction.PropertyInfo.PropertyType == typeof(string))
{
var value = Expression.Constant(((string)pInstruction.Value).Trim().ToLowerInvariant());
var exprToLower = Expression.Call(property, StringToLower);
return(Expression.Condition(
Expression.Equal(property, Expression.Constant(null)),
Expression.Constant(false),
Expression.Call(exprToLower, StringContains, value)
));
}
if (pInstruction.Value != null && (pInstruction.PropertyInfo.PropertyType == typeof(DateTime) || pInstruction.PropertyInfo.PropertyType == typeof(DateTime?)))
{
DateTime value = (DateTime)pInstruction.Value;
var day = Expression.Convert(Expression.Constant(value.Date), pInstruction.PropertyInfo.PropertyType);
var nextDay = Expression.Convert(Expression.Constant(value.Date.Add(TimeSpan.FromDays(1))), pInstruction.PropertyInfo.PropertyType);
return(Expression.AndAlso(Expression.GreaterThanOrEqual(property, day), Expression.LessThan(property, nextDay)));
}
}
return(Expression.Equal(property, Expression.Constant(pInstruction.Value)));
}
private static IQueryable <TSource> PerformOperation(IQueryable <TSource> source, FilterInstruction pInstruction, MethodInfo pMethodInfo)
{
var param = Expression.Parameter(typeof(TSource), "p");
Expression propertyExpr = pInstruction.PropertyInfo.GetMemberExpression(param);
Expression exprEqual = GetCompareExpression(pInstruction, propertyExpr);
var lambda = Expression.Lambda(exprEqual, param);
var method = pMethodInfo.MakeGenericMethod(new[] { typeof(TSource) });
var ret = method.Invoke(null, new object[] { source, lambda });
return((IQueryable <TSource>)ret);
}
