Empower plugins with more functionalities #5189

nirvn · 2024-04-17T03:55:45Z

This PR enables plugins to do the following:

retrieve map layers by name from a QgsProject instance
iterate through features from a vector layer
change a feature attribute value through the vector layer's changeAttributeValue(s) functions
retrieve field information (such as attribute index from a given field name)

The invoke.patch changes are being upstreamed, but since we're on 3.36 for now, we can enjoy vcpkg's patching powers 💪

Upstream PRs:

[qml] Add a couple of Q_INVOKABLE in QgsProject and QgsVectorLayer to ease layer and feature fetching + editing qgis/QGIS#57161
[qml] Make QgsFields a QGadet and make some functions Q_INVOKABLE qgis/QGIS#57166

Iterating through features is done like this:

let layers = qgisProject.mapLayersByName('Apiary')      
let layer = layers[0]      
let it = LayerUtils.createFeatureIteratorFromExpression(layer, "fid IN (47,48,49)")
while (it.hasNext())
{
  let feature = it.next()
  console.log(feature.id)
}

Editing a feature attribute is done like this:

let layers = qgisProject.mapLayersByName('Apiary')      
let layer = layers[0]      
let featureId = 47
let fieldIndex = layer.fields.lookupField('beekeeper')

layer.startEditing()
layer.changeAttributeValue(featureId, fieldIndex, "work!")
layer.commitChanges()

Creating a new feature, editing an attribute, and adding to a layer is done like this:

let feature = FeatureUtils.createFeature(layer)
feature.setAttribute("bin_uuid", string)
feature.setAttribute("check_datetime", new Date().toLocaleString())
        
layer.startEditing()
LayerUtils.addFeature(layer, feature)
layer.commitChanges()

Some more information to explain/justify some of the choices done here.

First, QML Javascript engine does not allow for non-const parameter by reference. This means that any C++ function that has a non-const & parameter can't be made Q_INVOKABLE. In practice, this is most impactful for the feature iterator here because we can't simply expose the QgsFeatureIterator::nextFeature( QgsFeature &feature ). It's a good lesson learned that is good to internalize now as we move forward :)

To deal with this, I've come up with a FeatureIterator which is Javascript friendly, with a bool hasNext() function and a QgsFeature next() function. I settled on this form after researching what kind of iterator template there is out there for Javascript.

This could eventually be upstreamed into QgsFeatureIterator itself. Looking at Qt's QList iterator for example, it does support Java-style iterators with hasNext() / next() / etc. (https://doc.qt.io/qt-6/java-style-iterators.html#java-style-iterators). This is a discussion that's worth having upstream as to whether we want this or not there.

Also, for the record, QML's Javascript engine does not have the capability to expand an object type via Object.prototype.my_function() = function {}, so adding functions to a given QObject or QGadget requires us to do it on the C++ side of things.

Finally, QML's Javascript engine does not allow the creation of objects directly in Javascript (other than via Qt.createComponent / Qt.createQmlObject which is not super graceful). This is why for e.g. Qt has a Qt.point() function to create a point object. That's why for e.g. we can't go let request = QgsFeatureRequest(...) on the Javascript side of things.

github-actions

clang-tidy made some suggestions

github-actions · 2024-04-17T04:54:46Z

src/core/utils/featureutils.cpp

@@ -27,9 +27,9 @@ FeatureUtils::FeatureUtils( QObject *parent )
 {
 }

-QgsFeature FeatureUtils::initFeature( QgsVectorLayer *layer, QgsGeometry geometry )
+QgsFeature FeatureUtils::createFeature( QgsVectorLayer *layer, QgsGeometry geometry )


warning: the parameter 'geometry' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param]

src/core/utils/featureutils.h:33:

- static Q_INVOKABLE QgsFeature createFeature( QgsVectorLayer *layer = nullptr, QgsGeometry geometry = QgsGeometry() ); + static Q_INVOKABLE QgsFeature createFeature( QgsVectorLayer *layer = nullptr, const QgsGeometry& geometry = QgsGeometry() );

Suggested change

QgsFeature FeatureUtils::createFeature( QgsVectorLayer *layer, QgsGeometry geometry )

QgsFeature FeatureUtils::createFeature( QgsVectorLayer *layer, const QgsGeometry& geometry )

github-actions · 2024-04-17T04:54:46Z

src/core/utils/featureutils.cpp

 {
-  QgsFeature f( layer->fields() );
+  QgsFeature f( layer ? layer->fields() : QgsFields() );


warning: implicit conversion 'QgsVectorLayer *' -> bool [readability-implicit-bool-conversion]

Suggested change

QgsFeature f( layer ? layer->fields() : QgsFields() );

QgsFeature f( layer != nullptr ? layer->fields() : QgsFields() );

github-actions · 2024-04-17T04:54:46Z

src/core/utils/featureutils.cpp

 {
-  QgsFeature f( layer->fields() );
+  QgsFeature f( layer ? layer->fields() : QgsFields() );


warning: variable name 'f' is too short, expected at least 3 characters [readability-identifier-length]

QgsFeature f( layer ? layer->fields() : QgsFields() ); ^

github-actions · 2024-04-17T04:54:46Z

src/core/utils/layerutils.h

+  public:
+    FeatureIterator( QgsVectorLayer *layer = nullptr, const QgsFeatureRequest &request = QgsFeatureRequest() )
+    {
+      if ( layer )


warning: implicit conversion 'QgsVectorLayer *' -> bool [readability-implicit-bool-conversion]

Suggested change

if ( layer )

if ( layer != nullptr )

github-actions · 2024-04-17T04:54:46Z

test/test_featureutils.cpp

@@ -26,7 +26,7 @@ TEST_CASE( "FeatureUtils" )

  QgsGeometry geometry = QgsGeometry::fromWkt( QStringLiteral( "Polygon (((8 8, 9 8, 8 9, 8 8)))" ) );

-  QgsFeature f = FeatureUtils::initFeature( vl.get(), geometry );
+  QgsFeature f = FeatureUtils::createFeature( vl.get(), geometry );


warning: variable 'f' of type 'QgsFeature' can be declared 'const' [misc-const-correctness]

Suggested change

QgsFeature f = FeatureUtils::createFeature( vl.get(), geometry );

QgsFeature const f = FeatureUtils::createFeature( vl.get(), geometry );

github-actions · 2024-04-17T04:54:46Z

test/test_featureutils.cpp

@@ -26,7 +26,7 @@

  QgsGeometry geometry = QgsGeometry::fromWkt( QStringLiteral( "Polygon (((8 8, 9 8, 8 9, 8 8)))" ) );

-  QgsFeature f = FeatureUtils::initFeature( vl.get(), geometry );
+  QgsFeature f = FeatureUtils::createFeature( vl.get(), geometry );


warning: variable name 'f' is too short, expected at least 3 characters [readability-identifier-length]

QgsFeature f = FeatureUtils::createFeature( vl.get(), geometry ); ^

qfield-fairy · 2024-04-17T05:58:05Z

🎉 Ta-daaa, freshly created APKs are available for 761669f: arm64-android

Other architectures

github-actions

clang-tidy made some suggestions

github-actions · 2024-04-17T12:57:28Z

src/core/utils/layerutils.cpp

@@ -199,6 +199,15 @@ QString LayerUtils::fieldType( const QgsField &field )
  return QVariant( field.type() ).typeName();
 }

+bool LayerUtils::addFeature( QgsVectorLayer *layer, QgsFeature feature )
+{
+  if ( layer )


warning: implicit conversion 'QgsVectorLayer *' -> bool [readability-implicit-bool-conversion]

Suggested change

if ( layer )

if ( layer != nullptr )

domi4484

Looks good to me

src/core/utils/featureutils.h

nirvn force-pushed the plugins branch from e8e3eb2 to c5c91f7 Compare April 17, 2024 04:18

github-actions bot reviewed Apr 17, 2024

View reviewed changes

nirvn added 12 commits April 18, 2024 16:38

Add gadgets and invocations

1734697

Put some create bits in place

f8eadaf

Add a FeatureIterator class to work around QML limitations

93a61a0

Make the FeatureIterator behave more JS-like

cee54a4

Edit patch to add QgsFields QML improvements

35a5f0f

Register QgsFields metatype

2c5539f

Add a LayerUtils function to add a feature to a given layer

f6162d5

Add the qrc: prefix to icons so plugins can use them

85987ca

Add an object name to the code reader for plugins to reach it

cd3311f

Add invokabel functions to QgsFeature

a009dc0

Add missing arguments to mainWindow.displayToast

3fd92ce

Update patch to take lesson learned into account

dbd5a40

nirvn force-pushed the plugins branch from 5a09b9d to dbd5a40 Compare April 18, 2024 09:38

nirvn mentioned this pull request Apr 18, 2024

Plugins management UI implementation #5195

Merged

domi4484 approved these changes Apr 18, 2024

View reviewed changes

src/core/utils/featureutils.h Outdated Show resolved Hide resolved

Address review

761669f

nirvn enabled auto-merge April 18, 2024 15:18

nirvn merged commit 32942c0 into master Apr 18, 2024
22 of 23 checks passed

nirvn deleted the plugins branch April 18, 2024 15:56

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Empower plugins with more functionalities #5189

Empower plugins with more functionalities #5189

nirvn commented Apr 17, 2024 •

edited

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qfield-fairy commented Apr 17, 2024 •

edited

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domi4484 left a comment

	QgsFeature FeatureUtils::createFeature( QgsVectorLayer *layer, QgsGeometry geometry )
	QgsFeature FeatureUtils::createFeature( QgsVectorLayer *layer, const QgsGeometry& geometry )

	QgsFeature f( layer ? layer->fields() : QgsFields() );
	QgsFeature f( layer != nullptr ? layer->fields() : QgsFields() );

	QgsFeature f = FeatureUtils::createFeature( vl.get(), geometry );
	QgsFeature const f = FeatureUtils::createFeature( vl.get(), geometry );

Empower plugins with more functionalities #5189

Empower plugins with more functionalities #5189

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nirvn commented Apr 17, 2024 • edited

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qfield-fairy commented Apr 17, 2024 • edited

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nirvn commented Apr 17, 2024 •

edited

qfield-fairy commented Apr 17, 2024 •

edited