假设列表中没有重复 ID,您需要的是外部连接。这是一个实现......我不保证最佳性能:
public static class LinqEx
{
public static IEnumerable<TResult>
LeftOuterJoin<TOuter, TInner, TKey, TResult>(
this IEnumerable<TOuter> outer,
IEnumerable<TInner> inner,
Func<TOuter, TKey> outerKeySelector,
Func<TInner, TKey> innerKeySelector,
Func<TOuter, TInner, TResult> resultSelector)
{
return outer
.GroupJoin(
inner,
outerKeySelector,
innerKeySelector,
(a, b) => new
{
a,
b
})
.SelectMany(
x => x.b.DefaultIfEmpty(),
(x, b) => resultSelector(x.a, b));
}
public static IEnumerable<TResult>
FullOuterJoin<TSet1, TSet2, TKey, TResult>(
this IEnumerable<TSet1> set1,
IEnumerable<TSet2> set2,
Func<TSet1, TKey> set1Selector,
Func<TSet2, TKey> set2Selector,
Func<TSet1, TSet2, TResult> resultSelector)
{
var leftJoin = set1.
LeftOuterJoin(
set2,
set1Selector,
set2Selector,
(s1, s2) => new {s1, s2});
var rightJoin = set2
.LeftOuterJoin(
set1,
set2Selector,
set1Selector,
(s2, s1) => new {s1, s2});
return leftJoin.Union(rightJoin)
.Select(x => resultSelector(x.s1, x.s2));
}
}
所以:
list1.FullOuterJoin(
list2,
list1Item => list1Item.Id,
list2Item => list2Item.Id,
(list1Item, list2Item) => {
if(listItem1!=null && listItem2!=null)
{
return merge(listItem1, listItem2);
}
return listItem1 ?? listItem2;
})