RDLC Without BC: When the Feedback Loop Is Longer Than the Workday

csharp #dotnet #businesscentral #rdlc #wpf

Nexus Claude: Every time a developer says "let me check how the report looks" — somewhere in an office, Business Central starts deploying.

Context

Developing RDLC reports for Business Central looks straightforward: edit the .rdlc file in Visual Studio, deploy the extension to BC, run the report, see the result.

The problem is in the word "deploy".

Every change — even nudging a field by two pixels — requires a full cycle: build, deploy, launch BC, navigate to the report, enter parameters. Five minutes at best. Multiply by twenty iterations a day and the workday becomes waiting.

The goal is simple:

Open RDLC and XML data → see the result. No BC. No deploy. Now.

Act One: Dead End in Visual Studio

The first thought — Visual Studio Report Designer has a Preview mode. So you can connect XML as a DataSource and view the report right there.

Create a Report Server Project. Open Designer. Try to add a DataSource — Designer won't allow it. Try connecting XML directly through Connection Properties — and get:

The XmlDP query is invalid.

Unexpected end of file has occurred.

The following elements are not closed: Column, Columns, DataItem, DataItems, ReportDataSet.

Open the .rdlc file manually. Inside — a hard lock:

<DataSources>

  <DataSource Name="DataSource">

    <ConnectionProperties>

      <DataProvider>SQL</DataProvider>

      <ConnectString />

    </ConnectionProperties>

  </DataSource>

</DataSources>

DataProvider=SQL. Can't change it through the UI. Designer won't allow it.

Nexus Claude: Microsoft isn't hiding the solution. Microsoft considers this scenario non-existent.

Official dead end. Moving on.

Act Two: Build It Yourself

If the tool doesn't exist — write it.

The architecture is simple: a WPF application takes two files — .rdlc and .xml with BC data — renders a PDF via ReportViewerCore.NETCore and displays the result through WebView2.

<PackageReference Include="ReportViewerCore.NETCore" Version="*" />

<PackageReference Include="Microsoft.Web.WebView2" Version="*" />

The rendering pipeline is transparent: XML is parsed into a DataTable, DataTable is passed to LocalReport, LocalReport renders PDF into a MemoryStream, WebView2 displays the bytes.

The only non-trivial part — column type inference. BC delivers everything as strings, but LocalReport needs proper types — otherwise numeric fields don't calculate, dates don't sort.

The InferColumnType logic walks through all non-empty values in a column:

int → decimal → DateTime → string

Dates deserve special attention. BC uses the dd/MM/yyyy format. Standard DateTime.TryParse with InvariantCulture won't recognize it. Explicit formats are required:

private static readonly string[] DateFormats =

{

    "dd/MM/yyyy", "dd/MM/yyyy HH:mm:ss",

    "yyyy-MM-dd", "yyyy-MM-ddTHH:mm:ss"

};



DateTime.TryParseExact(value, DateFormats,

    CultureInfo.InvariantCulture,

    DateTimeStyles.None, out _)

Without this, 19/02/2026 silently falls through to string — the report works, but date sorting breaks. Silently.

Nexus Claude: A system that stays quiet when something goes wrong isn't more reliable than one that crashes. It's just harder to diagnose.

Act Three: The Installer Is Its Own Story

A tool for yourself is one thing. A tool for the team requires an installer.

The choice is obvious — Inno Setup. Free, proven, no dependencies.

Problem one: the preprocessor

The first version of the script used #define for variables:

#define AppName "RDLC Report Tester"

#define AppVersion "1.01"

Inno Setup Compiler compiles without errors, but the [Setup] section is empty — values weren't substituted. Cause: file encoding. #define directives aren't read when saved as UTF-8 with BOM in certain configurations.

Fix — remove the preprocessor entirely. Hardcode values directly.

Result: ❌ ~20 minutes

Problem two: DownloadTemporaryFile

The installer needs to check for WebView2 Runtime and download it if missing. First version:

if not DownloadTemporaryFile(Url, FileName, '', @DownloadProgress) then

  // error

Compiler: type mismatch. DownloadTemporaryFile returns Int64 (byte count), not Boolean. On error — it throws an exception. Need try/except, not a return value check.

Result: ❌ ~15 minutes

Problem three: PublishSingleFile

The app was built as PublishSingleFile — one .exe, no dependencies alongside. Logical for distribution.

After installing via the installer, launch from Program Files — silence. Event Viewer says:

System.DllNotFoundException: Dll was not found.

at MS.Internal.WindowsBase.NativeMethodsSetLastError.SetWindowLongPtrWndProc

at MS.Win32.HwndSubclass.SubclassWndProc

PublishSingleFile extracts native DLLs into a temp folder next to the exe at runtime. In Program Files — no write permissions. WPF crashes before the window initializes. Silently.

Fix — disable PublishSingleFile in .csproj. The installer packages the entire publish\ folder into one Setup.exe. The end result is the same — one file to download — but native DLLs sit alongside the exe where they belong.

Result: ❌ ~30 minutes

Problem four: WebView2 and permissions

After the DLL fix the app launches, but crashes again — now with a different error code. WebView2 creates a user data folder next to the exe during initialization. In Program Files — no write permissions again.

// Before: WebView2 creates folder next to exe

await webView.EnsureCoreWebView2Async();



// After: explicit path in AppData

var env = await CoreWebView2Environment.CreateAsync(

    null,

    Path.Combine(

        Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),

        "RdlcReportTester", "WebView2"));

await webView.EnsureCoreWebView2Async(env);

Result: ✅

Nexus Claude: Two crashes in a row from the same root cause — no write permissions. Both silent. A good reminder: "installing in Program Files" isn't just a path — it's a contract with Windows about access rights.

Result

BC XML DataSource → RdlcRendererWpf → PDF Preview

Open the app, drag and drop .rdlc and .xml, see the report. No deployments, no BC sessions.

A careful reader will spot StackCollider Latvia SIA in the vendor list. An easter egg. Test data deserves character too.

<PackageReference Include="ReportViewerCore.NETCore" Version="*" />

<PackageReference Include="Microsoft.Web.WebView2" Version="*" />

Full source → github.com/stackcollider/rdlc-report-tester

Nexus Claude: A tool that speeds up development is code too. Sometimes it's more important to write it than the next report.