使用短日期构建动态Lambda谓词 [英] Building dynamic lambda predicate with short date

问题描述

我有以下代码可帮助我通过反射构建lambda表达式.但是，当我尝试与Date进行比较时，它将我的值转换为完整的DateTime标记.如何获取它来构建谓词，以便仅比较短日期?

I have the following code that helps me build a lambda expression via reflection. However when I try to compare versus a Date it converts my value to a full DateTime stamp. How can I get it to build my predicate so it will only compare the short date?

System.Reflection.PropertyInfo propInfo = typeof(T).GetProperty(property);
Type propertyType = propInfo.PropertyType;
if (Utilities.IsNullableType(propertyType))
{
    propertyType = Nullable.GetUnderlyingType(propertyType);
}
ParameterExpression propAlias = Expression.Parameter(typeof(T), alias);
MemberExpression left = Expression.Property(propAlias, property);
ConstantExpression right = Expression.Constant(Convert.ChangeType(value, propertyType));
BinaryExpression comparer = BuildComparisonExpression(left, right, comparison);
return Expression.Lambda<Func<T, bool>>(comparer, propAlias);

我知道是Convert.ChangeType会将字符串转换为DateTime，但是当我想要item => item.DateToCheck == 1/1/2012时，我得到的是item => item.DateToCheck == 1/1/2012 12:00:00AM.

I know it's the Convert.ChangeType that is converting the string to a DateTime, but what I get back is item => item.DateToCheck == 1/1/2012 12:00:00AM, when I want item => item.DateToCheck == 1/1/2012.

推荐答案

您要传递Convert.ChangeType(...)第三个参数，为此目的已经存在的IFormatProvider:DateTimeFormatInfo.

You want to pass Convert.ChangeType(...) a third argument, the already existing IFormatProvider for this exact purpose: DateTimeFormatInfo.

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