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构建C#Linq助手

linq-to-objects filter linq c#

Mike Q · 技术社区 · 14 年前

我正在尝试使用Linq构建一个实用方法,它将帮助我进行常见的Linq到对象搜索。

我有一个PropertyTbl对象,它引用了一个地址。 IEnumerable<PropertyTbl> . IEnumerable<Address> 一些搜索条件返回 IEnumerable<地址>

但是,我不知道如何将这两个插件连接在一起,因为虽然我可以在我的计算机上执行.Select() 为了得到可枚举的地址,我需要 IEnumerable<属性tbl> .

这是我的助手代码

    public static IEnumerable<Address> BuildAddressWhereClause(IEnumerable<Address> addresses, string value, AddressSearchOptions options)
    {
        string search = value.ToUpper();

        if ((options & AddressSearchOptions.Address1To4) == AddressSearchOptions.Address1To4)
        {
            addresses = addresses.Where(o => o.Address1.ToUpper().Contains(search)
                                             || o.Address2.ToUpper().Contains(search)
                                             || o.Address3.ToUpper().Contains(search)
                                             || o.Address4.ToUpper().Contains(search));
        }

        if ((options & AddressSearchOptions.City) == AddressSearchOptions.City)
        {
            addresses = addresses.Where(o => o.City.ToUpper().Contains(search));
        }

        if ((options & AddressSearchOptions.PostCode) == AddressSearchOptions.PostCode)
        {
            addresses = addresses.Where(o => o.PostCode.ToUpper().Contains(search));
        }

        return addresses;
    }

IEnumerable<PropertyTbl> properties = ...;

IEnumerable<PropertyTbl> filteredProperties = <use my address helper somehow>;

// this works but I need the properties as the result not just the addresses
IEnumerable<Address> filteredAddresses = AddressUtils.FilterAddresses(properties.Select(o => o.Address), "1 High Street", ...);

我可以通过将助手代码直接放入正在加载/筛选属性的代码中来做我想做的事情,但是我不能重用它。

1 回复 | 直到 14 年前

erikkallen 14 年前

安 IEnumerable<PropertyTbl> 不是一个 IEnumerable<Address> Address PropertyTable (除非你改变主意 BuildAddressWhereClause 采取行动 IEnumerable<属性tbl>

像这样的事情应该可以做到:

public static IEnumerable<T> BuildAddressWhereClause<T>(IEnumerable<T> source, string value, AddressSearchOptions options, Func<T, Address> addressExtractor) { 
    string search = value.ToUpper(); 

    if ((options & AddressSearchOptions.Address1To4) == AddressSearchOptions.Address1To4) { 
        source = source.Where(o => addressExtractor(o).Address1.ToUpper().Contains(search) 
                                   || addressExtractor(o).Address2.ToUpper().Contains(search) 
                                   || addressExtractor(o).Address3.ToUpper().Contains(search) 
                                   || addressExtractor(o).Address4.ToUpper().Contains(search)); 
    } 

    if ((options & AddressSearchOptions.City) == AddressSearchOptions.City) { 
        source = source.Where(o => addressExtractor(o).City.ToUpper().Contains(search)); 
    } 

    if ((options & AddressSearchOptions.PostCode) == AddressSearchOptions.PostCode) { 
        source = source.Where(o => addressExtractor(o).PostCode.ToUpper().Contains(search)); 
    } 

    return source; 
}

然后你像这样调用它

IEnumerable<PropertyTbl> properties = ...;      
IEnumerable<PropertyTbl> filteredProperties = AddressUtils.FilterAddresses(properties, "whatever", AddressSearchOptions.Whatever, p => p.Address);