如何在 Linq 中使用不同的计数？

Question

The extention method below does not have Distinct and Count

public static IEnumerable<Something> ToFilterModel(this IEnumerable<Product> products)
{
    var v = products
        .SelectMany(x => x.ProductVariants)
        .GroupBy(x => x.OptionId)
        .Select(x => new
        {
            Id = x.Key.ToString(),
            Items = x.Select(x => new Item { Id = x.ValueId, Text = x.Value.OptionValue })
        });
    return v;
}

Given the input below it should return 2 Items rows and not 3, since i am interested for ValueIds and also Count by ValueIds

how should i modify it?

More spesifically it should return items with rows 1 and 2 and also

Count equal to 1 for the first row and Count equal to 2 for the second row.

Answer 1

You could group by ValueId the grouped options, like:

Items = x
    .GroupBy(y => y.ValueId)
    .Select(z => new Item { Id = z.Key, Text = z.First().Value.OptionValue, Count = z.Count() })

The result will be:

{
   "Id":1,
   "Items":[
      {
         "Id":1,
         "Text":"text1",
         "Count":1
      },
      {
         "Id":2,
         "Text":"text2",
         "Count":2
      }
   ]
}

NOTE: the Text is the count of grouped value ids.

The whole code:

var v = products
        .SelectMany(x => x.ProductVariants)
        .GroupBy(x => x.OptionId)
        .Select(x => new
        {
            Id = x.Key.ToString(),
            Items = x
                .GroupBy(y => y.ValueId)
                .Select(z => new Item { Id = z.Key, Text = z.First().Value.OptionValue, Count = z.Count() })
        });