Question

我有一个类项目，如

public class Item
{
   public int Id {get;set;}
   public string Name {get;set;}
   public string PartialDescription {get;set;}
   public string FullDescription {get;set;} 
   public doulbe Price {get;set;}
}

我想有一个动态自定义查询方法SearchOverAnyFields（），可以接受任意数量的Item对象的属性，如：

// key is an input string variable

// one query 
var results = myItems.SearchOverAnyFields(x => x.Name.Contains(key) || x.PartialDescription.Contains(key) || x.Price.ToString().Contains(key));

// or another query 
var results2 = myItems.SearchOverAnyFields(x => x.Name.Contains(key) || x.PartialDescription.Contains(key) || x.Price.ToString().Contains(key) 
|| x.FullDescription.Contains(key));

// or another query
var results3 = myItems.SearchOverAnyFields(x => x.PartialDescription.Contains(key) ||  x.FullDescription.Contains(key));

请帮忙。

Answer 1

这样的事可能会为你做好工作......

    public static IEnumerable<Item> SearchOverAnyFields(this IEnumerable<Item> items, string key, params Func<Item,string>[] fields)
    {
        return 
            from item in items 
            from field in fields.
            Where(field => field(item) != null && field(item).Contains(key)) 
            select item;
    }


    public static void ExampleUsage(object[] args)
    {
        var items = new List<Item> { new Item { Name = "badger" }, new Item { PartialDescription = "badger" }, new Item { } };

        // searches items for any item that has "badger" in it's name or PartialDescription
        var result = items.SearchOverAnyFields("badger", i => i.Name, i => i.PartialDescription);

        foreach (var res in result)
            Debug.WriteLine(res);
    }

调用ExampleUsage（）会将两个语句打印到调试控制台，以验证它们是否为您构建ToString方法所需的正确项目。

Answer 2

我不确定您在寻找什么 - 使用Where运算符可以轻松实现您想要的功能。

var results = myItems.Where(x => x.Name.Contains(key) || 
    x.PartialDescription.Contains(key) || x.Price.ToString().Contains(key));

// or another query 
var results2 = myItems.Where(x => x.Name.Contains(key) || 
    x.PartialDescription.Contains(key) || x.Price.ToString().Contains(key) 
    || x.FullDescription.Contains(key));

// or another query
var results3 = myItems.Where(x => x.PartialDescription.Contains(key) ||  
    x.FullDescription.Contains(key));

这是否符合您的要求？

动态LINQ：使用.NET Contains方法生成动态搜索方法

2 个答案: