Linq PredicateBuilder - 多个OR

Question

我正在尝试使用PredicateBuilder,如此处所述 - http://www.albahari.com/nutshell/predicatebuilder.aspx

以下代码

var predicate = PredicateBuilder.False<StreetDTO>();

        predicate = predicate.Or(p => p.Locality.Contains(criteria.Locality));
        predicate = predicate.Or(p => p.Name.Contains(criteria.Name));
        predicate = predicate.Or(p => p.Town.Contains(criteria.Town));

        List<StreetDTO> streetData = StreetData.Instance();

        var streetList = from street in streetData.Where(predicate)
                         select street;

根据这个例子,据我所知,这应该有效

var newKids  = Product.ContainsInDescription ("BlackBerry", "iPhone");

var classics = Product.ContainsInDescription ("Nokia", "Ericsson")
                      .And (Product.IsSelling());
var query =
  from p in Data.Products.Where (newKids.Or (classics))
  select p;

但我得到的只是

错误1无法从用法中推断出方法'System.Linq.Enumerable.Where(System.Collections.Generic.IEnumerable,System.Func)'的类型参数.尝试显式指定类型参数.

我正试图在LINQ'在职'获得一些理解,所以如果这是一个简单的问题,请道歉.

Answer 1

啊; 你的清单是使用IEnumerable<T>扩展方法(而不是IQueryable<T>) - 尝试:

var streetList = from street in streetData.AsQueryable().Where(predicate)
                 select street;

Answer 2

尝试编译谓词:

var streetList = from street in streetData.Where(predicate.Compile())
                 select street;