QGIS Development Environment

Development assistant for QGIS-related projects following the mqs (My QGIS Stuff) repository standards. This skill helps with creating QGIS Processing Toolbox scripts, QGIS plugins, and maintaining proper project structure.

What This Skill Does

Instructions

Critical Rules

**ALWAYS enforce these requirements:**

1. **Testing First**

- Write tests alongside implementation

- Run tests before marking work complete

- All test files go in `testing/` directory

- Never implement features without corresponding tests

2. **Version Management**

- Add `__version__ = "x.y.z"` to all code files

- Follow semantic versioning (MAJOR.MINOR.PATCH)

- Update `CHANGELOG.md` with every version bump

- Include version number and date in changelog entries

Repository Structure

Understand the two main code categories:

**Processing Toolbox Scripts** (`Scripts/` directory):

**QGIS Plugins** (`Plugins/` directory):

Creating New Processing Scripts

When user requests a new QGIS Processing script:

1. Create directory structure:

```bash

mkdir -p docs/[SubprojectName]/testing

```

2. Create script at `Scripts/[scriptname].py` with:

- Version header: `__version__ = "0.1.0"`

- Class inheriting from `QgsProcessingAlgorithm`

- Group set to "MQS Tools"

- Comprehensive help text

- Proper parameter definitions

3. Create documentation files:

- `docs/[SubprojectName]/README.md` - User guide

- `docs/[SubprojectName]/REQUIREMENTS.md` - Technical specs

- `docs/[SubprojectName]/CHANGELOG.md` - Start with v0.1.0 entry

4. Create test file in `docs/[SubprojectName]/testing/`

5. Update main `README.md` with new subproject

Creating New QGIS Plugins

When user requests a new plugin:

1. Suggest using QGIS Plugin Builder first if starting from scratch

2. Set up structure:

```bash

mkdir -p Plugins/[plugin_name]

mkdir -p docs/[plugin_name]/testing

```

3. Ensure plugin has:

- `__init__.py` with `classFactory()` function

- `metadata.txt` with proper metadata (qgisMinimumVersion=3.40)

- Main plugin class file

- `resources.qrc` for resources

- `Makefile` or `pb_tool.cfg` for building

- `test/` directory for tests

4. Create documentation:

- `docs/[plugin_name]/README.md` - Installation and usage

- `docs/[plugin_name]/REQUIREMENTS.md` - Technical specs

- `docs/[plugin_name]/CHANGELOG.md` - Version history

5. Compile resources:

```bash

cd Plugins/[plugin_name]

pyrcc5 -o resources.py resources.qrc

```

6. Update main `README.md`

Modifying Existing Code

When user requests changes to existing code:

1. Read the current version from the file

2. Determine version bump type:

- PATCH: Bug fixes, minor changes

- MINOR: New features, backward compatible

- MAJOR: Breaking changes

3. Update `__version__` in code

4. Update or create entry in `CHANGELOG.md`:

```markdown

## [x.y.z] - YYYY-MM-DD

### Added/Changed/Fixed

- Description of changes

```

5. Write or update tests for the changes

6. Run tests to verify

Testing Workflow

Before marking any work complete:

1. Verify test file exists in appropriate `testing/` directory

2. Run tests:

```bash

python -m unittest discover -s testing

```

3. Ensure all tests pass

4. If tests fail, fix issues before proceeding

Documentation Standards

Every subproject must have:

Common Requirements

Examples

Example 1: Creating a New Processing Script

```

User: Create a new QGIS script that merges all shapefiles in a directory

Steps:

1. Create docs/ShapefileMerger/testing/

2. Write Scripts/shapefile_merger.py with:

- __version__ = "0.1.0"

- Class inheriting QgsProcessingAlgorithm

- group() returns "MQS Tools"

- Input: folder parameter

- Output: merged layer

3. Create docs/ShapefileMerger/README.md

4. Create docs/ShapefileMerger/REQUIREMENTS.md

5. Create docs/ShapefileMerger/CHANGELOG.md with v0.1.0

6. Write test_shapefile_merger.py in testing/

7. Run tests

8. Update main README.md

```

Example 2: Updating Existing Script

```

User: Add option to filter by geometry type in vectors2gpkg

Steps:

1. Read Scripts/vectors2gpkg.py (current version: 0.8.3)

2. Implement geometry filter parameter

3. Update __version__ to "0.9.0" (new feature = MINOR bump)

4. Update docs/vectors2gpkg/CHANGELOG.md:

## [0.9.0] - 2024-XX-XX

### Added

- Geometry type filter option

5. Update or add test case in testing/

6. Run tests

7. Verify all tests pass

```

Example 3: Creating a New Plugin

```

User: Create a plugin for batch layer styling

Steps:

1. Suggest: "Let's use QGIS Plugin Builder first"

2. After builder output:

- Move to Plugins/batch_styler/

- Create docs/batch_styler/testing/

3. Update metadata.txt:

- version=0.1.0

- qgisMinimumVersion=3.40

- experimental=True

4. Create documentation files in docs/batch_styler/

5. Compile resources:

cd Plugins/batch_styler && make

6. Create tests in Plugins/batch_styler/test/

7. Update main README.md

```

Constraints