ExpressionFuncIQueryableTResult expression示例

以下是一个简单的示例，其中expression返回一个IQueryable对象：

public class Person { public int Id { get; set; } public string Name { get; set; } public int Age { get; set; } }

public class PersonRepository { public IQueryable GetPersons() { var persons = new List { new Person { Id = 1, Name = "John", Age = 30 }, new Person { Id = 2, Name = "Jane", Age = 25 }, new Person { Id = 3, Name = "Bob", Age = 40 }, new Person { Id = 4, Name = "Alice", Age = 22 }, new Person { Id = 5, Name = "Tom", Age = 35 }, };

    return persons.AsQueryable();
}

public Expression<Func<IQueryable<Person>>> GetPersonsExpression()
{
    return () => GetPersons();
}

}

// 使用表达式获取IQueryable对象 var repository = new PersonRepository(); var personsExpression = repository.GetPersonsExpression(); var persons = personsExpression.Compile()(); // 获取IQueryable对象

// 使用IQueryable对象进行查询 var query = persons.Where(p => p.Age > 30); foreach (var person in query) { Console.WriteLine(person.Name);