C# 需要一个递归函数来解决典型的电子商务多变量问题

假设我有以下数据（为了可读性，使用伪代码）：

我可以通过LINQ获得数据，如下所示：

var myVariations = myProduct.Variations.ToList();

如何将这些变化映射到这样的结构中（对于易趣交易API）：

var ebayVariations = [
    {
        Name = "Red-S-34",
        Value = [
                                       // yes, these are arrays with only one item
            { Name = "Color", Values = [{Value = "Red"}] },
            { Name = "Size", Values = [{Value = "S"}] },
            { Name = "Length", Values = [{Value = "34" }] }
        ]
    },
    /* etc for all possible combinations */
];

---

显然，

Values

数组只包含一个值这一事实有点奇怪；但对于eBay的交易API，如果我在一个变量中列出多个值（与这种递归的东西相比，这很容易做到），它会抱怨或者，如果您熟悉易趣交易API，我如何才能让它以“最佳”的方式工作，与易趣预期的变体上市方式保持一致（如果您愿意，可以通过AddFixedPricedItem调用）。

我对易趣交易API一无所知，但是（最后一步是放弃递归，转而使用聚合）。

我对术语做了一些无关紧要的更改，但写了一些澄清的评论

    public IEnumerable<Combination> GetCombinations(Variation[] variations, int variationIndex, IEnumerable<VariationPosition> aggregatedPositions)
    {
        // We should choose one position from every variation, 
        // so we couldn't produce combination till we reach end of array. 
        if (variationIndex < variations.Length)
        {
            // Pick current variation.  
            var currentVariation = variations[variationIndex];

            // Every variation has list of possible positions (Color could be Green, Redm, Blue, etc.).
            // So we should walk through all the positions 
            foreach (var val in currentVariation.Positions)
            {
                // Current position. Variation's name will be used during creating result Combination.
                var position = new VariationPosition()
                {
                    Name = currentVariation.Name,
                    Value = val
                };
                // Add position to already aggregated on upper levels of recursion positions.
                var newPositions = aggregatedPositions.Concat(Enumerable.Repeat(position, 1));

                // So we picked some variation position 
                // Let's go deeper.
                var combinations = this.GetCombinations(variations, variationIndex + 1, newPositions );

                // This piece of code allows us return combinations in iterator fashion.
                foreach (var combination in combinations)
                {
                    yield return combination;
                }
            }
        }
        else
        {
            // We reached end of variations array 
            // I mean we have one position of every variation. 

            // We concatenate name of positions in order to create string like "Red-S-34"
            var name = aggregatedPositions.Aggregate("", (res, v) => res += v.Name);

            // This code is a little bit naive, I'm too lazy to create proper infrastructure,
            // But its mission is to create content for property Value of your ebayVariations item. 
            var value = aggregatedPositions
                .Select(v => new { Name = v.Name, Values = new[] { new { Value = v.Value } } })
                .ToArray();

            // And we return completed combination.
            yield return new Combination()
            {
                Name = name,
                Value = value,
            };
        }
    }

---

我不知道如何将我的变体模型与CartesianProduct方法相适应。你解决了吗？我已经为你开始了一个实现，然后被召集到一个会议上。很抱歉，但我希望它能起作用。好吧，我解决了它。我得到了字符串结果，如：“Color=White，Size=s，Length=36”和“Color=White，Size=S，Length=38”等…我不知道如何维护对象结构。因此，在将对象传递给CartesianProduct函数之前，我将名称和值连接到字符串中；基本上：

variations.Select（v=>v.Values.Select（a=>v.Name+“=”+a.Value））

（我的实际实现为这些值提供了一些额外的元数据，这就是为什么它们是对象，而不是数组的原因）。我仍在努力，很可能会接受这个答案。谢谢和+1！+1。我已经实现了Linq/CartesianProduct方法的一个黑客版本。我现在在这个问题上花费了太多时间，但我稍后会回到你的答案，看看它是否更合适。@alex sashok想知道你是否可以帮助解决这个问题N

    public IEnumerable<Combination> GetCombinations(Variation[] variations, int variationIndex, IEnumerable<VariationPosition> aggregatedPositions)
    {
        // We should choose one position from every variation, 
        // so we couldn't produce combination till we reach end of array. 
        if (variationIndex < variations.Length)
        {
            // Pick current variation.  
            var currentVariation = variations[variationIndex];

            // Every variation has list of possible positions (Color could be Green, Redm, Blue, etc.).
            // So we should walk through all the positions 
            foreach (var val in currentVariation.Positions)
            {
                // Current position. Variation's name will be used during creating result Combination.
                var position = new VariationPosition()
                {
                    Name = currentVariation.Name,
                    Value = val
                };
                // Add position to already aggregated on upper levels of recursion positions.
                var newPositions = aggregatedPositions.Concat(Enumerable.Repeat(position, 1));

                // So we picked some variation position 
                // Let's go deeper.
                var combinations = this.GetCombinations(variations, variationIndex + 1, newPositions );

                // This piece of code allows us return combinations in iterator fashion.
                foreach (var combination in combinations)
                {
                    yield return combination;
                }
            }
        }
        else
        {
            // We reached end of variations array 
            // I mean we have one position of every variation. 

            // We concatenate name of positions in order to create string like "Red-S-34"
            var name = aggregatedPositions.Aggregate("", (res, v) => res += v.Name);

            // This code is a little bit naive, I'm too lazy to create proper infrastructure,
            // But its mission is to create content for property Value of your ebayVariations item. 
            var value = aggregatedPositions
                .Select(v => new { Name = v.Name, Values = new[] { new { Value = v.Value } } })
                .ToArray();

            // And we return completed combination.
            yield return new Combination()
            {
                Name = name,
                Value = value,
            };
        }
    }

var allCombinations = this.GetCombinations(inputVariations, 0, new VariationPosition[0]).ToArray();