Developing SolidWorks C# Code

Documentation-First Workflow

CRITICAL: Base knowledge of SolidWorks API is inconsistent. Always consult documentation Types, Enums, Docs, Examples, Learnings. You ABSOLUTELY MUST run your code before claiming success. Don't bother with

dotnet build

, use

dotnet run

immediately after code changes. JUST COMPILING IS NOT ENOUGH.

Workflow checklist

Copy and track progress through complex SolidWorks tasks:

SolidWorks Development Progress:
- [ ] Step 1: Review API documentation for required methods
- [ ] Step 2: Write code with named parameters
- [ ] Step 3: Add error handling and null checks
- [ ] Step 4: Verify functionality via `dotnet run`
- [ ] Step 5: Add cleanup and resource disposal

Required steps before writing code

1. Use grep to explore the docs: The grep-optimized documentation structure makes it easy to find specific methods quickly or extract member documentation programmatically

2. Read documentation: Available in the skill folder:

   • API Reference in

     ./types/

     and

     ./enums/

     (method signatures, parameters, enum values)
   • Programming Guide in

     ./docs/

     (best practices, patterns)
   • Code Examples in

     ./examples/

     (proven implementations)
   • Troubleshooting Guide in

     ./learnings/

     (documented solutions to common problems)

3. If documentation is unavailable: Run

   /download-solidworks-docs

   command to download the API documentation, then continue. If the command fails, ABORT and notify user

4. Verify approach: Confirm alignment with current SDK conventions

Grep Use Cases

Find specific methods quickly

# Find CreateArc method documentation
grep -r "CreateArc" .claude/skills/developing-solidworks/types/IModelDoc2/

# Get just that method's file
cat .claude/skills/developing-solidworks/types/IModelDoc2/CreateArc2.md

Extract member documentation programmatically

# Get all methods in IModelDoc2
ls .claude/skills/developing-solidworks/types/IModelDoc2/*.md | grep -v "_overview"

# Extract all method signatures
grep "^**Signature**:" .claude/skills/developing-solidworks/types/IModelDoc2/*.md

Search by metadata

# Find all members in "Application Interfaces" category
grep -r "category: Application Interfaces" .claude/skills/developing-solidworks/types/

# Find all methods (not properties)
grep -r "kind: method" .claude/skills/developing-solidworks/types/

Find and use enums (each enum is a directory with _overview.md and individual value files):

# Find enum directory
ls .claude/skills/developing-solidworks/enums/ | grep -i "endconditions"

# Read enum overview
cat .claude/skills/developing-solidworks/enums/swEndConditions_e/_overview.md

# Find specific enum value
grep -r "swEndCondBlind" .claude/skills/developing-solidworks/enums/
cat .claude/skills/developing-solidworks/enums/swEndConditions_e/swEndCondBlind.md

# Find enum usage in examples
grep -r "swEndConditions_e" .claude/skills/developing-solidworks/examples/

Navigate by category

# View all types in a category
cat .claude/skills/developing-solidworks/index/by_category.md | grep -A 20 "Application Interfaces"

# View statistics
cat .claude/skills/developing-solidworks/index/statistics.md

Troubleshooting Guide

IMPORTANT: When encountering errors or unexpected behavior, consult

./learnings/

first. This directory contains documented solutions to real issues encountered during development, including:

• Problem symptoms and error messages
• Root cause analysis
• Working solutions with code examples
• Best practices to avoid the issue

When encountering new issues not covered in learnings, document the problem, investigation, and solution in a new file with appropriate frontmatter.

SolidWorks-Specific Patterns

SDK library references

The SolidWorks SDK works with .NET Framework only. Find latest SDK libraries via find_api_redist.py. It will return the main folder with all SolidWorks.Interop.* assemblies.

Code quality requirements

Named parameters (required for methods with many parameters):

// Good - Clear what each value represents
  IFeature extrudeFeature = swFeatureMgr.FeatureExtrusion3(
      Sd: true,                                          // Single direction
      Flip: false,                                       // Don't flip side to cut
      Dir: false,                                        // Don't flip extrusion direction
      //...
  );

// Avoid - Unclear what values mean
IFeature extrudeFeature = swFeatureMgr.FeatureExtrusion3(true, false, false, (int)swEndConditions_e.swEndCondBlind, (int)swEndConditions_e.swEndCondBlind, 0.1, 0, false, false, false, false, 0, 0, false,
   false, false, false, false, false, true, (int)swStartConditions_e.swStartSketchPlane, 0, false);

Error handling (SolidWorks API frequently returns null):

IModelDoc2 doc = swApp.ActiveDoc as IModelDoc2;
if (doc == null)
{
    throw new InvalidOperationException("No active document");
}

Return value checks (many methods return bool for success):

bool success = doc.Extension.SelectByID2(
    Name: "Face1",
    Type: "FACE",
    X: 0, Y: 0, Z: 0,
    Append: false,
    Mark: 0,
    Callout: null,
    SelectOption: 0
);

if (!success)
{
    throw new Exception("Selection failed");
}

Type casting (consult documentation for exact return types, cast appropriately):

// Enum casting - cast to int for API input, cast from int for readable output
Dir1: (int)swEndConditions_e.swEndCondBlind                          // API parameter
var status = (swSketchCheckFeatureStatus_e)sketch.CheckFeatureUse(); // Return value

// Interface casting - check docs for return type, chain casts as needed
ISketch sketch = (ISketch)((IFeature)doc.SelectionManager.GetSelectedObject6(1, -1)).GetSpecificFeature2();

// Always verify return types in documentation before casting

Run code before claiming success (you MUST run your new code using

dotnet run

or similar. Just building it is NOT enough)

Common patterns

Part creation: Use

GetUserPreferenceStringValue

to avoid hardcoding template paths.

swModel = (ModelDoc2)swApp.NewDocument(
      TemplateName: swApp.GetUserPreferenceStringValue((int)swUserPreferenceStringValue_e.swDefaultTemplatePart),
      PaperSize: 0,
      Width: 0,
      Height: 0);

Document state: Check before operations

if (doc.GetType() != (int)swDocumentTypes_e.swDocPART)
{
    throw new InvalidOperationException("Operation requires part document");
}

Code Verification Checklist

Before delivering code:

Code Quality:
- [ ] Consulted API documentation (types/, enums/, docs/, examples/, learnings/)
- [ ] Used latest SDK library references
- [ ] Applied documented API patterns
- [ ] Used named parameters
- [ ] Added null checks and error handling
- [ ] Included SolidWorks-specific comments
- [ ] Handled units correctly
- [ ] Code is complete and runnable
- [ ] Code was validated at least once via `dotnet run` or `dotnet test`

When to Ask for Clarification

• Requested functionality may not be possible with SolidWorks API
• Multiple significantly different approaches exist
• Task requires specific SolidWorks version or configuration details
• Documentation is ambiguous or contradictory

Quick Examples

Creating a part with extrusion

1. Consult API documentation for

   CreateExtrudeFeatureSolid2

   (search in

   ./types/

   )
2. Write code:

using SolidWorks.Interop.sldworks;
using SolidWorks.Interop.swconst;

// Get application and create new part
ISldWorks swApp = new SldWorks.SldWorks();
IModelDoc2 doc = swApp.NewDocument(
      TemplateName: swApp.GetUserPreferenceStringValue((int)swUserPreferenceStringValue_e.swDefaultTemplatePart),
      PaperSize: 0,
      Width: 0,
      Height: 0);

if (doc == null) throw new Exception("Failed to create document");

// Create sketch on front plane
doc.Extension.SelectByID2(
    Name: "Front Plane",
    Type: "PLANE",
    X: 0, Y: 0, Z: 0,
    Append: false,
    Mark: 0,
    Callout: null,
    SelectOption: 0
);
doc.SketchManager.InsertSketch(true);
doc.SketchManager.CreateCenterRectangle(0, 0, 0, 0.05, 0.05, 0);
doc.SketchManager.InsertSketch(true);

// Create extrude
doc.Extension.SelectByID2(
    Name: "Sketch1",
    Type: "SKETCH",
    X: 0, Y: 0, Z: 0,
    Append: false,
    Mark: 0,
    Callout: null,
    SelectOption: 0
);
IFeature feature = doc.FeatureManager.FeatureExtrusion2(
    Sd: true,                                          // Single direction
    Flip: false,                                       // Don't flip side to cut
    Dir: false,                                        // Don't flip extrusion direction
    Dir2: (int)swEndConditions_e.swEndCondBlind,      // End condition for direction 2
    Dir1: (int)swEndConditions_e.swEndCondBlind,      // End condition for direction 1
    D1: 0.1,                                           // Depth in meters
    D2: 0,                                             // Depth for direction 2
    Dchk1: false,                                      // Draft outward direction 1
    Dchk2: false,                                      // Draft outward direction 2
    Ddir1: false,                                      // Draft direction 1
    Ddir2: false,                                      // Draft direction 2
    Dang1: 0,                                          // Draft angle direction 1
    Dang2: 0,                                          // Draft angle direction 2
    Offstatus: false                                   // Offset from surface
);

if (feature == null) throw new Exception("Extrusion failed");