OutSystems Developer Cloud (ODC) Custom Code Analyzer

ℹ️ This component is unofficial and unsupported by OutSystems.

⚡ Screenshot showing the development of an ODC External Library in Visual Studio. The ODC Custom Code Analyzer flags several rule violations in the Problems panel. A related Quick Fix menu is open for one rule violation, offering to "Fix this type mapping" so the field correctly matches its OSDataType.PhoneNumber. You can get identical functionality in Visual Studio Code and Rider. ⚡

Overview

When you want to extend your ODC apps with custom C# code, you do so with the External Libraries SDK. This SDK allows you to write C# code that you can call from your ODC apps.

Although IntelliSense in your IDE guides the available SDK decorators and their syntax, it does not guide the rules you must follow (for example, on naming and design decisions). This guidance is provided when uploading your project's built assembly to the ODC Portal, where you get feedback on rule violations. Using this component brings that feedback forward and gives you real-time feedback on compliance with the rules as you write the code. You also get real-time guidance on best practices and automatic fixes.

Technical Primer

When you upload your project's built assembly to the ODC Portal, it does not have access to the underlying code—the ODC Portal checks compliance with the rules by reflecting on the assembly's metadata.

This component, built from scratch, implements the rules using the rich code analysis APIs of Roslyn, the .NET compiler.

graph TB
    subgraph User["👩‍💻 User"]
        code["Writes code"]:::userArea
    end

    subgraph Roslyn["🛠 Roslyn"]
        ast["Generates AST<br/>and semantic model"]:::roslyn
    end

    subgraph CustomCode_Analyzer["🔍 CustomCode-Analyzer"]
        analysis["Code analysis<br/>and fix provider"]:::analyzerArea
    end

    subgraph IDE["🖥 IDE"]
        display["Displays diagnosis and fixes"]:::ideArea
    end

    code --> ast
    ast --> analysis
    analysis --> display
    display --> code

    Roslyn -."using Roslyn APIs".-> CustomCode_Analyzer

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Code analysis phases

The analyzer operates in two distinct phases, registered through the Roslyn AnalysisContext:

1. Symbol analysis phase
   Triggered by RegisterSymbolAction, this phase performs immediate syntax and semantic analysis on individual declarations as you type. For example, when you declare a method, the analyzer instantly checks if its name starts with an underscore and reports a violation if it does (NameBeginsWithUnderscoreRule). These diagnostics appear immediately in your IDE's Problems window.

2. Compilation end phase
   Registered via RegisterCompilationEndAction, this phase runs after all symbols have been processed and the semantic model is complete. For example, it ensures exactly one [OSInterface] exists across your project by maintaining a ConcurrentDictionary of interface declarations and validating their uniqueness (NoSingleInterfaceRule or ManyInterfacesRule). These diagnostics may appear with a slight delay as they require complete semantic analysis.

Code fixes for certain rules

Wherever we can infer a single, unambiguous fix, we provide an automated code fix through the Roslyn CodeFixProvider. Currently, code fixes are available for these rules:

Rule description	OS-ELG-MODL code	Action performed
Non-public OSInterface	05004	Make interface public
Non-public OSStructure	05010	Make struct public
Non-public OSStructureField	05011	Make property/field public
Non-public OSIgnore	05012	Make [OSIgnore] property/field public
Missing structure decoration	05024	Add [OSStructure] attribute to struct
Name begins with underscores	05022	Remove leading _ in method names
Unsupported type mapping	05017	Change field/property type to match DataType

The code fix suggestions appear as "lightbulb" actions (or "quick actions") in your IDE. If you accept the fix, the analyzer modifies your source code to make it compliant with the respective rule.

How to use

Visual Studio 2022 (Enterprise, Pro and, Community editions)

You can use the auto-updating extension from the Visual Studio Marketplace. Simply install the extension from the Visual Studio Marketplace.

💡 Want your extension to stay up to date? Enable auto-updates in Visual Studio: Go to Tools > Options > Environment > Extensions and check Automatically update extensions.

If your project references the External Libraries SDK (OutSystems.ExternalLibraries.SDK), the extension should automatically start providing feedback on your code.

To ensure real-time feedback for compilation end phase rules (and not just at the point of build), you need to configure your Visual Studio's background analysis:

1. Select Tools > Options.
2. From the left menu select C# > Advanced.
3. Set both Run background code analysis for and Show compiler errors and warnings to Entire solution.
4. Make sure the Run code analysis in separate process box is unchecked.

Others

Add the NuGet package as a dev dependency to your ODC external libraries project:

dotnet add package CustomCode.Analyzer

If your project references the External Libraries SDK (OutSystems.ExternalLibraries.SDK), the package should automatically start providing feedback on your code.

The NuGet package cannot be automatically updated—be sure to update regularly to get the latest features.

Visual Studio Code

To ensure real-time feedback for compilation end phase rules (and not just at the point of build), you need to configure your Visual Studio's background analysis:

1. Open the command palette (Ctrl+Shift+P).
2. Search for "roslyn". Set the Dotnet › Background Analysis: Analyzer Diagnostics Scope to fullSolution.

🐛 For the code fix to work, you need to be switch to using the pre-release version of the C# extension. See this issue.

TODO

See here.

Feedback and contributions

Please report bugs and feature requests here. Feel free to leave general feedback on the OutSystems Community Forum post.

PRs are welcome. Code quality improvements, new features (especially those unassigned and listed here), and documentation improvements are all welcome 🤗 All changes to Analyzer code should pass all existing tests (dotnet test), and all new features should be covered by new tests. Please format any new code with csharpier.