ApiController.cs

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Web.Http.OData;
using Microsoft.AspNetCore.Mvc;
using Newtonsoft.Json.Linq;
using Sitecore.Commerce.Core;
using Sitecore.Services.Examples.Catalog.Commands;
using Sitecore.Services.Examples.Catalog.Pipelines.Arguments;

namespace Sitecore.Services.Examples.Catalog.Controllers
{
    public class ApiController : CommerceController
    {
        protected internal const string CreateUpdateSellableItemStr = "createUpdateSellableItem";
        protected internal const string ProductsStr = "products";

        public ApiController(IServiceProvider serviceProvider, CommerceEnvironment globalEnvironment)
            : base(serviceProvider, globalEnvironment)
        {
        }

        [HttpPut]
        [Route("CreateUpdateSellableItem()")]
        public async Task<IActionResult> CreateUpdateSellableItem([FromBody] ODataActionParameters value)
        {
            if (!ModelState.IsValid)
            {
                return new BadRequestObjectResult(ModelState);
            }

            if (!value.ContainsKey(CreateUpdateSellableItemStr))
            {
                return new BadRequestObjectResult(value);
            }

            //Handling scenarios where the input is already converted into JArray (postman) or passed through as string
            JArray products;
            if (value[CreateUpdateSellableItemStr] is JArray == false)
            {
                var payload = JObject.Parse(value[CreateUpdateSellableItemStr].ToString());
                products = (JArray) payload[ProductsStr];
            }
            else
            {
                products = value[CreateUpdateSellableItemStr] as JArray;
            }

            var sellableItemArguments = new List<CreateUpdateSellableItemArgument>();
            
            foreach (var product in products)
            {
                var sellableItemArgument = new CreateUpdateSellableItemArgument();
                var productid = product["productid"].ToString();
                sellableItemArgument.ProductId = productid;

                var description = product["description"].ToString();
                sellableItemArgument.Description = description;

                var name = product["name"].ToString();
                sellableItemArgument.Name = name;

                var displayName = product["displayname"].ToString();
                sellableItemArgument.DisplayName = displayName;

                var listprice = product["listprice"].ToString();
                var isDecimal = decimal.TryParse(listprice, out var n);
                if (isDecimal)
                {
                    sellableItemArgument.ListPrice = Convert.ToDecimal(listprice);
                }

                var variants = (JArray) product["variants"];
                foreach (var variant in variants)
                {
                    var variantArg = new CreateUpdateSellableItemVariantArgument(sellableItemArgument.ProductId, variant["variantid"].ToString());

                    var variantListPrice = variant["listprice"].ToString();
                    if (decimal.TryParse(variantListPrice, out var outPrice))
                    {
                        variantArg.ListPrice = Convert.ToDecimal(variantListPrice);
                    }

                    sellableItemArgument.Variants.Add(variantArg);
                }

                sellableItemArguments.Add(sellableItemArgument);
            }

            var result = await Command<CreateUpdateSellableItemCommand>().Process(CurrentContext, sellableItemArguments);

            return new ObjectResult(result);
        }
    }
}