linq groupby Months 并将任何缺失的月份添加到分组数据中

发布于 2024-10-18 16:27:50 字数 653 浏览 2 评论 0原文

我创建了一个 linq 语句，它似乎工作正常。我可能写得正确，也可能不正确，但它返回了我的预期结果。

     var grouped = RewardTransctions.GroupBy(t => new
        {
            t.PurchaseDate.Value.Month
        }).Select(g => new TransactionDetail()
        {
            Month =
                g.Where(w=>w.EntryType==1).Select(
                    (n =>
                     n.PurchaseDate.Value.Month))
                .First(),
            TransactionAmount = g.Count()
        });

现在结果返回 5 个按月份分组的值。是否可以将 TransactionAmount = 0 的其他 7 个缺失月份添加到其中？

我疯狂的原因是我试图将这些值绑定到图表上，并让我的 x 轴基于月份。目前仅显示 5 个月的记录。如果我的数据一个月没有返回任何值，我想添加 0 值。

有什么建议吗？

原文

I have created a linq statement which seems to be working ok. I may or maynot have written it correctly however its returning my expected results.

     var grouped = RewardTransctions.GroupBy(t => new
        {
            t.PurchaseDate.Value.Month
        }).Select(g => new TransactionDetail()
        {
            Month =
                g.Where(w=>w.EntryType==1).Select(
                    (n =>
                     n.PurchaseDate.Value.Month))
                .First(),
            TransactionAmount = g.Count()
        });

Now the results are returning 5 values grouped by months. Is it possible to add the 7 other missing months with a TransactionAmount = 0 to them?

The reason for my madness is I am trying to bind these values to a chart and having my x axis based on months. Currently its only showing the 5 months of records. If my data doesnt return any value for a month I some how want to add in the 0 value.

Any suggestions?

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旧故 2024-10-25 16:27:50

如果使用.ToLookup(...)，就非常简单。

var lookup =
    (from w in RewardTransctions
     where w.EntryType == 1
     select w).ToLookup(w => w.PurchaseDate.Value.Month);

var grouped =
    from m in Enumerable.Range(1, 12)
    select new TransactionDetail()
    {
        Month = m,
        TransactionAmount = lookup[m].Count(),
    };

对于几个简单的 LINQ 查询来说怎么样？

It's very simple if you use .ToLookup(...).

var lookup =
    (from w in RewardTransctions
     where w.EntryType == 1
     select w).ToLookup(w => w.PurchaseDate.Value.Month);

var grouped =
    from m in Enumerable.Range(1, 12)
    select new TransactionDetail()
    {
        Month = m,
        TransactionAmount = lookup[m].Count(),
    };

How's that for a couple of simple LINQ queries?

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亽野灬性zι浪 2024-10-25 16:27:50

当您使用 LINQ to Objects 时，此查询应该可以解决问题：

var grouped = 
    from month in Enumerable.Range(1, 12)
    select new TransactionDetail()
    {
        Month = month,
        TransactionAmount = RewardTransactions
            .Where(t => t.PurchaseDate.Value.Month == month).Count()
    };

当 RewardTransactions 是 IQueryable 时，您应该首先调用 AsEnumerable() 关于它。

When you're using LINQ to Objects, this query should do the trick:

var grouped = 
    from month in Enumerable.Range(1, 12)
    select new TransactionDetail()
    {
        Month = month,
        TransactionAmount = RewardTransactions
            .Where(t => t.PurchaseDate.Value.Month == month).Count()
    };

When RewardTransactions however is an IQueryable, you should first call AsEnumerable() on it.

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雨落星ぅ辰 2024-10-25 16:27:50

为什么不这样做：

var grouped =
    RewardTransctions.GroupBy(t => t.PurchaseDate.Value.Month).Select(
        g => new TransactionDetail { Month = g.Key, TransactionAmount = g.Count() }).ToList();
for (var i = 1; i <= 12; ++i)
{
    if (grouped.Count(x => x.Month == i) == 0)
    {
        grouped.Add(new TransactionDetail { Month = i, TransactionAmount = 0 });
    }
}

它不完全是 LINQ，而是直接的。我还稍微简化了您的 LINQ 查询；-)

Why not do it just like this:

var grouped =
    RewardTransctions.GroupBy(t => t.PurchaseDate.Value.Month).Select(
        g => new TransactionDetail { Month = g.Key, TransactionAmount = g.Count() }).ToList();
for (var i = 1; i <= 12; ++i)
{
    if (grouped.Count(x => x.Month == i) == 0)
    {
        grouped.Add(new TransactionDetail { Month = i, TransactionAmount = 0 });
    }
}

It's not entirely LINQ, but straight forward. I also simplified your LINQ query a bit ;-)

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