[英]Using distinct in LINQ where >1 column involved
I have a list of records, 3 of the properties of which are 我有一个记录列表,其中3个属性是
VendorId
VendorName
VendorDesc
There could be multiple instances of the same vendor. 同一供应商可能有多个实例。
What I wish to do is retrieve a "distinct" list of "VendorNames" with the VenderDesc property as well. 我想做的是同时使用VenderDesc属性检索“ VendorNames”的“不同”列表。
Returning one property is fine ie 归还一项财产是可以的
var myVendorNameList = myRecords.Select(r=>r.VendorName).Distinct();
However I wish to add the VendorDesc to this list after which I interate through to output(Razor View) the content using foreach ie 但是我希望将VendorDesc添加到此列表中,然后使用foreach进行交互以输出(Razor View)内容
foreach (var item in myVendors)
{
Name: @item.VendorName
Desc: @item.VendorDesc
}
Thanks in advance. 提前致谢。
The simplest way is to GroupBy
the field you want and decide which of the duplicate records you want: 最简单的方法是
GroupBy
你想要的领域,决定要重复的哪些记录:
myRecords.GroupBy(r=>r.VendorName)
.Select(g => g.First());
您可以使用GroupBy
。这也将返回VendorId
属性,但我认为这不是问题。
myRecords.GroupBy(x => x.VendorName).Select(g => g.First());
I think, using the morelinq's DistinctBy (as LB mentioned) or creating your own one would be more readable 我认为,使用morelinq的 DistinctBy(如LB所述)或创建自己的一个将更具可读性
public static IEnumerable<T> DistinctBy<T, TKey>(this IEnumerable<T> source,
Func<T, TKey> keySelector)
{
HashSet<TKey> keys = new HashSet<TKey>();
return source.Where(x => keys.Add(keySelector(x)));
}
You can now use it as 您现在可以将其用作
myVendorNameList = myRecords.DistinctBy(r=>r.VendorName);
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