ProductVariant CompareAtPrice can't be set to empty

[lantram]

Perhaps I'm missing something, but it doesn't seem possible to set CompareAtPrice to null or empty. :?

decimal? price = _largest(variant.Price, variant.CompareAtPrice);
await variantService.UpdateAsync(variant.Id.Value,
    new ProductVariant()
    {
        Price = price,
        CompareAtPrice = null
    });

[nozzlegear]

This is related #284. The CompareAtPrice property is not included if the value is null, which means it can't be unset. That's a bug obviously, but the fix isn't any better since by including the null value you can then accidentally remove it when updating a variant too. I'm actively working on finding a better solution for updating objects, since either setting has undesired behavior that can bite the dev if they don't know what to watch for.

For now you should be able to work around the behavior by creating your own class for the data you're sending, and then extend the ProductVariantService with a custom method that accepts that class. Something like this:

public class ProductVariantCompareAtPrice
{
    [JsonProperty("price")]
    public decimal Price { get; set; }

	[JsonProperty("compare_at_price", DefaultValueHandling = DefaultValueHandling.Include)]
	public decimal? CompareAtPrice { get; set; }
}

public class CustomProductVariantService : ProductVariantService
{
    public CustomProductVariantService(string domain, string token) : base(domain, token) { }

    public async Task<ProductVariant> UpdateCompareAtPriceAsync(long variantId, ProductVariantCompareAtPrice data)
    {
		var req = PrepareRequest($"variants/{variantId}.json");
		var content = new JsonContent(new
		{
			variant = data
		});

		return await ExecuteRequestAsync<ProductVariant>(req, HttpMethod.Put, content, "variant");
    }
}

(Edit: updated with correct DefaultValueHandling attribute.)

[lantram]

I wrote a horrible kludge that seems to work good enough for now.

public class ProductVariantServiceEx : ProductVariantService
{
    public ProductVariantServiceEx(string myShopifyUrl, string shopAccessToken) : base(myShopifyUrl, shopAccessToken) { }

    public virtual async Task<ProductVariant> UpdateAsync(long productVariantId, ProductVariant variant)
    {
        // BUGFIX: KLUDGE: If variant.CompareAtPrice is set to 0, then force it to empty
        string json = await (new JsonContent(new { variant })).ReadAsStringAsync();
        if (json.Contains("\"compare_at_price\":0.0}")
        || json.Contains("\"compare_at_price\":0.0,"))
        {
            json = json.Replace("\"compare_at_price\":0.0", "\"compare_at_price\":\"\"");

            return await ExecuteRequestAsync<ProductVariant>(
                PrepareRequest($"variants/{productVariantId}.json"),
                HttpMethod.Put,
                new StringContent(json, Encoding.UTF8, "application/json"),
                "variant");
        }
        else
        {
            return await base.UpdateAsync(productVariantId, variant);
        }
    }
}

[nozzlegear]

That should do, glad you found a workaround!

[lantram]

Yep. It seems to work pretty well. Whenever I know I want to update CompareAtPrice, I simply use ProductVariantServiceEx instead of ProductVariantService. Problem solved.

In general, I could use ProductVariantServiceEx all the time - since 0.0 as a CompareAtPrice isn't really valid (or at least anything useful) - but whatever, it works when I know I need it. : )