以前要不是使用扩展方法

要么使用如(t==2&&判断条件)||（s==1&&判断条件）

其实可以简单的实现扩展一个whereIf即可（abp实现），如下所示

···

///

/// Filters a by given predicate if given condition is true.

///

/// Queryable to apply filtering

/// A boolean value

/// Predicate to filter the query

/// Filtered or not filtered query based on

public static IQueryable WhereIf(this IQueryable query, bool condition, Expression<Func<T, bool>> predicate)

{

return condition

? query.Where(predicate)

: query;

}

/// 
    /// Filters a 
      by given predicate if given condition is true.    /// 
    /// Queryable to apply filtering    /// A boolean value    /// Predicate to filter the query    /// 
    
     Filtered or not filtered query based on 
     
        public static IQueryable
    
      WhereIf
     
      (this IQueryable
      
        query, bool condition, Expression
       
        
         > predicate)    {        return condition            ? query.Where(predicate)            : query;    }
        
       
      
     
    

···

使用

例如：

var query = _taskRepository.GetAll().Include(t => t.AssignedPerson)

.WhereIf(input.State.HasValue, t => t.State == input.State.Value)

.WhereIf(!input.Filter.IsNullOrEmpty(), t => t.Title.Contains(input.Filter))

.WhereIf(input.AssignedPersonId.HasValue, t => t.AssignedPersonId == input.AssignedPersonId.Value);