Notes

I get it now, bro! You want to:

1. Extract unique Supplier_Id values and call API once with Supplier_Id eq xxx or yyy.


2. Extract unique (Supplier_Id, Inv_Mast_Uid) pairs and call API once with Supplier_Id eq xxx and Inv_Mast_Uid eq yyy.


3. Merge all data from 4 API calls into a single final model.




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🔥 Optimized Solution

Step 1: Fetch Initial Invoice Data

// Fetch header and line details
HttpResponseMessage headerResponse = await FetchP21InvoiceDetailsAsync(baseHeaderUrl, result.AccessToken!);
HttpResponseMessage lineResponse = await FetchP21InvoiceDetailsAsync(baseLineUrl, result.AccessToken!);

// Ensure both API calls succeeded
if (!headerResponse.IsSuccessStatusCode || !lineResponse.IsSuccessStatusCode)
return; // Handle error case

// Read JSON response
string headerJson = await headerResponse.Content.ReadAsStringAsync();
string lineJson = await lineResponse.Content.ReadAsStringAsync();

// Parse JSON to Lists
List<EpicorP21HdrModel> headerData = JsonConvert.DeserializeObject<List<EpicorP21HdrModel>>(headerJson)!;
List<EpicorP21LineModel> lineData = JsonConvert.DeserializeObject<List<EpicorP21LineModel>>(lineJson)!;

// Combine Header and Line Data
var combinedInvoiceData = from headers in headerData
join lines in lineData on headers.invoice_no equals lines.invoice_no
select new EpicorP21CombinedModel
{
Bill2Name = headers.bill2_name,
Bill2Address1 = headers.bill2_address1,
Bill2Address2 = headers.bill2_address2,
LineNo = lines.line_no,
ManufacturerId = lines.supplier_id,
DistProdId = lines.item_id,
DistProdDesc = lines.item_desc,
ExtendedAqCost = lines.cogs_amount,
InvMastUid = lines.inv_mast_uid // Store inv_mast_uid for second API
};

List<EpicorP21CombinedModel> invoiceDataList = combinedInvoiceData.ToList();


---

Step 2: Fetch Supplier Details API (1st API Call)

// Extract Unique Supplier IDs
var uniqueSupplierIds = invoiceDataList
.Select(x => x.ManufacturerId)
.Where(id => !string.IsNullOrEmpty(id))
.Distinct()
.ToList();

// Construct Supplier Filter
string supplierFilter = uniqueSupplierIds.Count > 0
? string.Join(" or ", uniqueSupplierIds.Select(id => $"Supplier_Id eq '{id}'"))
: "";

List<SupplierModel> supplierData = new List<SupplierModel>();

if (!string.IsNullOrEmpty(supplierFilter))
{
string supplierDetailsUrl = $"{baseSupplierUrl}?$filter={Uri.EscapeDataString(supplierFilter)}";
HttpResponseMessage supplierResponse = await FetchP21InvoiceDetailsAsync(supplierDetailsUrl, result.AccessToken!);

if (supplierResponse.IsSuccessStatusCode)
{
string supplierJson = await supplierResponse.Content.ReadAsStringAsync();
supplierData = JsonConvert.DeserializeObject<List<SupplierModel>>(supplierJson)!;
}
}


---

Step 3: Fetch Supplier & Inv_Mast_Uid Details API (2nd API Call)

// Extract Unique (Supplier ID, Inv Mast UID) Pairs
var uniqueSupplierUidPairs = invoiceDataList
.Where(x => !string.IsNullOrEmpty(x.ManufacturerId) && !string.IsNullOrEmpty(x.InvMastUid))
.Select(x => new { x.ManufacturerId, x.InvMastUid })
.Distinct()
.ToList();

// Construct Supplier & UID Filter
string supplierUidFilter = uniqueSupplierUidPairs.Count > 0
? string.Join(" or ", uniqueSupplierUidPairs.Select(x => $"(Supplier_Id eq '{x.ManufacturerId}' and Inv_Mast_Uid eq '{x.InvMastUid}')"))
: "";

List<SupplierUidModel> supplierUidData = new List<SupplierUidModel>();

if (!string.IsNullOrEmpty(supplierUidFilter))
{
string supplierUidDetailsUrl = $"{baseSupplierUidUrl}?$filter={Uri.EscapeDataString(supplierUidFilter)}";
HttpResponseMessage supplierUidResponse = await FetchP21InvoiceDetailsAsync(supplierUidDetailsUrl, result.AccessToken!);

if (supplierUidResponse.IsSuccessStatusCode)
{
string supplierUidJson = await supplierUidResponse.Content.ReadAsStringAsync();
supplierUidData = JsonConvert.DeserializeObject<List<SupplierUidModel>>(supplierUidJson)!;
}
}


---

Step 4: Merge All Data into Final Model

var finalCombinedData = from invoice in invoiceDataList
join supplier in supplierData on invoice.ManufacturerId equals supplier.SupplierId into supplierJoin
from supplierInfo in supplierJoin.DefaultIfEmpty()
join supplierUid in supplierUidData on new { invoice.ManufacturerId, invoice.InvMastUid }
equals new { supplierUid.SupplierId, supplierUid.InvMastUid } into supplierUidJoin
from supplierUidInfo in supplierUidJoin.DefaultIfEmpty()
select new EpicorP21FinalModel
{
Bill2Name = invoice.Bill2Name,
Bill2Address1 = invoice.Bill2Address1,
Bill2Address2 = invoice.Bill2Address2,
LineNo = invoice.LineNo,
ManufacturerId = invoice.ManufacturerId,
DistProdId = invoice.DistProdId,
DistProdDesc = invoice.DistProdDesc,
ExtendedAqCost = invoice.ExtendedAqCost,
SupplierName = supplierInfo?.SupplierName ?? "Unknown", // From First API
AdditionalField = supplierUidInfo?.SomeField ?? "N/A" // From Second API
};

List<EpicorP21FinalModel> finalDataList = finalCombinedData.ToList();


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🔥 Why This Approach?

✅ Only 2 Extra API Calls (instead of calling API in a loop for each ID).
✅ Efficient Filtering (Supplier_Id eq xxx or yyy, Supplier_Id eq xxx and Inv_Mast_Uid eq yyy).
✅ Final Merge Using LINQ for a single complete model.

Now, finalDataList contains all required merged data in one go! 🚀 Let me know if you need any changes, bro! 💪🔥