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我想创建以下WHERE子句动态表情:动态创建一个表达式调用方法EntityFunctions.DiffDays
context.Cars.
Where(c => EntityFunctions.DiffDays(c.Created, c.Created) == null).
ToList()
这是我使用,以创建表达代码:
var parameter = Expression.Parameter(typeof(Car), "c");
var property = Expression.Property(parameter, "Created");
var function = Expression.Call(typeof(EntityFunctions), "DiffDays",
null, property, property);
var comparison = Expression.Equal(function, Expression.Constant(null));
var result = Expression.Lamda<Func<Car, bool>>(comparison, parameter);
结果显示(它似乎缺少“EntityFunctions.DiffDays”):
{c => (DiffDays(c.Created, c.Created) == null)}
当我尝试执行:
context.Cars.Where(result.Compile()).ToList()
我得到的错误信息:
此功能只能从 LINQ调用,以实体
你知道我缺少什么?是因为它只显示“DateDiff”而不是“EntityFunctions.DateDiff”
谢谢。亚当