使用linq查询对象数组

I would like to know how can I query an array of objects. For example I have an array object like CarList. So CarList[0] would return me the object Car. Car has properties Model and Make. Now, I want to use linq to query the array CarList to get the Make of a Car whose Model is say "bmw". I tried the following

我想知道如何查询对象数组。例如，我有一个像CarList这样的数组对象。所以CarList [0]会把对象Car给我。汽车有属性Model和Make。现在，我想使用linq查询数组CarList以获取模型名为“bmw”的Make of a Car。我尝试了以下内容

var carMake = from item in CarList where item .Model == "bmw" select s.Make;

I get the error

我收到了错误

Could not find an implementation of the query pattern for source type CarList[]

无法找到源类型CarList []的查询模式的实现

I cannot change CarList from array to something like List<> since CarList is retured to me as array from a webservice.

我无法将CarList从数组更改为List <>之类的东西，因为CarList从Web服务中作为数组返回到我。

Kindly let me know how this can be solved. Would be great if you can explain using C# code.

请告诉我这是如何解决的。如果您可以使用C＃代码解释，那将会很棒。

Thanks in advance.

提前致谢。

2 个解决方案

#1

Add:

加：

using System.Linq;

to the top of your file.

到你的文件的顶部。

And then:

接着：

Car[] carList = ...
var carMake = 
    from item in carList
    where item.Model == "bmw" 
    select item.Make;

or if you prefer the fluent syntax:

或者如果您更喜欢流利的语法：

var carMake = carList
    .Where(item => item.Model == "bmw")
    .Select(item => item.Make);

Things to pay attention to:

需要注意的事项：

The usage of item.Make in the select clause instead if s.Make as in your code.
如果s.Make在代码中，则使用item.Make在select子句中。
You have a whitespace between item and .Model in your where clause
在where子句中，item和.Model之间有一个空格

#2

The best way to do it:

最好的方法：

ContexteDAO.ContexteDonnees instantiate a new context.

ContexteDAO.ContexteDonnees实例化一个新的上下文。

public static Destination[] Rechercher(string aCodeDestination, string aDénomination, string aVille, string aPays, Single aLatitude, Single aLongitude, string aContinent,
                                            string aZoneGeo, string aRelief,string aObservation)
    {
        IEnumerable<Destination> DestinationRecherche;

        DestinationRecherche = ContexteDAO.ContexteDonnees.Destinations;

        if(!string.IsNullOrEmpty(aCodeDestination))
        {
            DestinationRecherche = DestinationRecherche.Where(a=>a.CodeDestination.Contains(aCodeDestination));
        }
        if (!string.IsNullOrEmpty(aDénomination))
        {
            DestinationRecherche = DestinationRecherche.Where(a => a.Dénomination.Contains(aDénomination));
        }
        if (!string.IsNullOrEmpty(aVille))
        {
            DestinationRecherche  = DestinationRecherche.Where(a => a.Ville.Contains(aVille));
        }
        if (!string.IsNullOrEmpty(aPays))
        {
            DestinationRecherche  = DestinationRecherche.Where(a => a.Pays.Contains(aPays));
        }
        if (aLatitude != 0)
        {
            DestinationRecherche = DestinationRecherche.Where(a => a.Latitude.Equals(aLatitude));
        }
        if (aLongitude != 0)
        {
            DestinationRecherche = DestinationRecherche.Where(a => a.Longitude.Equals(aLongitude));
        }
        if (!string.IsNullOrEmpty(aContinent))
        {
            DestinationRecherche = DestinationRecherche.Where(a => a.Continent.Contains(aContinent));
        }
        if(!string.IsNullOrEmpty(aZoneGeo))
        {                DestinationRecherche = DestinationRecherche.Where(a => a.ZoneGeographique.Contains(aZoneGeo));
        }        
        if(!string.IsNullOrEmpty(aRelief))
        {
            DestinationRecherche = DestinationRecherche.Where(a =>a.Relief.Contains(aRelief));
        }
        if (!string.IsNullOrEmpty(aObservation))
        {
            DestinationRecherche = DestinationRecherche.Where(a => a.ObservationsDestination.Contains(aObservation));
        }
        return DestinationRecherche.ToArray();
    }

#1