[英]LINQ PredicateBuilder multiple OR starting with PredicateBuilder.True<>
[英]Linq PredicateBuilder - Multiple ORs
我正在嘗試使用PredicateBuilder,如下所述 - http://www.albahari.com/nutshell/predicatebuilder.aspx
以下代碼
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;
根據這個例子,據我所知,這應該有效
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
錯誤1無法從用法中推斷出方法'System.Linq.Enumerable.Where(System.Collections.Generic.IEnumerable,System.Func)'的類型參數。 嘗試顯式指定類型參數。
我正試圖在LINQ'在職'獲得一些理解,所以如果這是一個簡單的問題,請道歉。
啊; 你的列表使用IEnumerable<T>
擴展方法(而不是IQueryable<T>
) - 嘗試:
var streetList = from street in streetData.AsQueryable().Where(predicate)
select street;
嘗試編譯謂詞:
var streetList = from street in streetData.Where(predicate.Compile())
select street;
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