QGIS API Documentation 3.33.0-Master (bf22a165b3)
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qgsfieldexpressionwidget.cpp
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1
2/***************************************************************************
3 qgsfieldexpressionwidget.cpp
4 --------------------------------------
5 Date : 01.04.2014
6 Copyright : (C) 2014 Denis Rouzaud
8***************************************************************************
9* *
10* This program is free software; you can redistribute it and/or modify *
11* it under the terms of the GNU General Public License as published by *
12* the Free Software Foundation; either version 2 of the License, or *
13* (at your option) any later version. *
14* *
15***************************************************************************/
16
17#include <QHBoxLayout>
18#include <QObject>
19#include <QKeyEvent>
20
21#include "qgsapplication.h"
24#include "qgsfieldproxymodel.h"
25#include "qgsdistancearea.h"
26#include "qgsfieldmodel.h"
27#include "qgsvectorlayer.h"
28#include "qgsproject.h"
31
33 : QWidget( parent )
34 , mExpressionDialogTitle( tr( "Expression Dialog" ) )
35 , mDistanceArea( nullptr )
36
37{
38 QHBoxLayout *layout = new QHBoxLayout( this );
39 layout->setContentsMargins( 0, 0, 0, 0 );
40
41 mCombo = new QComboBox( this );
42 mCombo->setEditable( true );
43 mCombo->setSizePolicy( QSizePolicy::MinimumExpanding, QSizePolicy::Minimum );
44 const int width = mCombo->minimumSizeHint().width();
45 mCombo->setMinimumWidth( width );
46
47 mFieldProxyModel = new QgsFieldProxyModel( mCombo );
48 mFieldProxyModel->sourceFieldModel()->setAllowExpression( true );
49 mCombo->setModel( mFieldProxyModel );
50
51 mButton = new QToolButton( this );
52 mButton->setSizePolicy( QSizePolicy::Minimum, QSizePolicy::Minimum );
53 mButton->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mIconExpression.svg" ) ) );
54
55 layout->addWidget( mCombo );
56 layout->addWidget( mButton );
57
58 connect( mCombo->lineEdit(), &QLineEdit::textEdited, this, &QgsFieldExpressionWidget::expressionEdited );
59 connect( mCombo->lineEdit(), &QLineEdit::editingFinished, this, &QgsFieldExpressionWidget::expressionEditingFinished );
60 connect( mCombo, static_cast < void ( QComboBox::* )( int ) > ( &QComboBox::activated ), this, &QgsFieldExpressionWidget::currentFieldChanged );
61 connect( mButton, &QAbstractButton::clicked, this, &QgsFieldExpressionWidget::editExpression );
62 connect( mFieldProxyModel, &QAbstractItemModel::modelAboutToBeReset, this, &QgsFieldExpressionWidget::beforeResetModel );
63 connect( mFieldProxyModel, &QAbstractItemModel::modelReset, this, &QgsFieldExpressionWidget::afterResetModel );
64
65 mExpressionContext = QgsExpressionContext();
66 mExpressionContext << QgsExpressionContextUtils::globalScope()
68
69 mCombo->installEventFilter( this );
70}
71
73{
74 mExpressionDialogTitle = title;
75}
76
77void QgsFieldExpressionWidget::setFilters( QgsFieldProxyModel::Filters filters )
78{
79 mFieldProxyModel->setFilters( filters );
80}
81
83{
84 mCombo->lineEdit()->setClearButtonEnabled( allowEmpty );
85 mFieldProxyModel->sourceFieldModel()->setAllowEmptyFieldName( allowEmpty );
86}
87
89{
90 return mFieldProxyModel->sourceFieldModel()->allowEmptyFieldName();
91}
92
94{
95 QHBoxLayout *layout = dynamic_cast<QHBoxLayout *>( this->layout() );
96 if ( !layout )
97 return;
98
99 if ( isLeft )
100 {
101 QLayoutItem *item = layout->takeAt( 1 );
102 layout->insertWidget( 0, item->widget() );
103 }
104 else
105 layout->addWidget( mCombo );
106}
107
109{
110 mDistanceArea = std::shared_ptr<const QgsDistanceArea>( new QgsDistanceArea( da ) );
111}
112
114{
115 return mCombo->currentText();
116}
117
122
124{
125 return asExpression();
126}
127
128bool QgsFieldExpressionWidget::isValidExpression( QString *expressionError ) const
129{
130 QString temp;
131 return QgsExpression::checkExpression( currentText(), &mExpressionContext, expressionError ? *expressionError : temp );
132}
133
135{
136 return !mFieldProxyModel->sourceFieldModel()->isField( currentText() );
137}
138
139QString QgsFieldExpressionWidget::currentField( bool *isExpression, bool *isValid ) const
140{
141 QString text = currentText();
142 const bool valueIsExpression = this->isExpression();
143 if ( isValid )
144 {
145 // valid if not an expression (ie, set to a field), or set to an expression and expression is valid
146 *isValid = !valueIsExpression || isValidExpression();
147 }
148 if ( isExpression )
149 {
150 *isExpression = valueIsExpression;
151 }
152 return text;
153}
154
156{
157 return mFieldProxyModel->sourceFieldModel()->layer();
158}
159
161{
162 mExpressionContextGenerator = generator;
163}
164
166{
167 QgsVectorLayer *vl = qobject_cast< QgsVectorLayer * >( layer );
168
169 if ( mFieldProxyModel->sourceFieldModel()->layer() )
170 disconnect( mFieldProxyModel->sourceFieldModel()->layer(), &QgsVectorLayer::updatedFields, this, &QgsFieldExpressionWidget::reloadLayer );
171
172 if ( vl )
173 mExpressionContext = vl->createExpressionContext();
174 else
175 mExpressionContext = QgsProject::instance()->createExpressionContext();
176
177 mFieldProxyModel->sourceFieldModel()->setLayer( vl );
178
179 if ( mFieldProxyModel->sourceFieldModel()->layer() )
180 connect( mFieldProxyModel->sourceFieldModel()->layer(), &QgsVectorLayer::updatedFields, this, &QgsFieldExpressionWidget::reloadLayer, Qt::UniqueConnection );
181}
182
183void QgsFieldExpressionWidget::setField( const QString &fieldName )
184{
185 if ( fieldName.isEmpty() )
186 {
187 setRow( -1 );
188 emit fieldChanged( QString() );
189 emit fieldChanged( QString(), true );
190 return;
191 }
192
193 QModelIndex idx = mFieldProxyModel->sourceFieldModel()->indexFromName( fieldName );
194 if ( !idx.isValid() )
195 {
196 // try to remove quotes and white spaces
197 QString simpleFieldName = fieldName.trimmed();
198 if ( simpleFieldName.startsWith( '"' ) && simpleFieldName.endsWith( '"' ) )
199 {
200 simpleFieldName.remove( 0, 1 ).chop( 1 );
201 idx = mFieldProxyModel->sourceFieldModel()->indexFromName( simpleFieldName );
202 }
203
204 if ( !idx.isValid() )
205 {
206 // new expression
207 mFieldProxyModel->sourceFieldModel()->setExpression( fieldName );
208 idx = mFieldProxyModel->sourceFieldModel()->indexFromName( fieldName );
209 }
210 }
211 const QModelIndex proxyIndex = mFieldProxyModel->mapFromSource( idx );
212 mCombo->setCurrentIndex( proxyIndex.row() );
214}
215
217{
218 mFieldProxyModel->sourceFieldModel()->setFields( fields );
219}
220
221void QgsFieldExpressionWidget::setExpression( const QString &expression )
222{
224}
225
227{
228 const QString currentExpression = asExpression();
229 QgsVectorLayer *vl = layer();
230
231 const QgsExpressionContext context = mExpressionContextGenerator ? mExpressionContextGenerator->createExpressionContext() : mExpressionContext;
232
233 QgsExpressionBuilderDialog dlg( vl, currentExpression, this, QStringLiteral( "generic" ), context );
234 if ( mDistanceArea )
235 {
236 dlg.setGeomCalculator( *mDistanceArea );
237 }
238 dlg.setWindowTitle( mExpressionDialogTitle );
239 dlg.setAllowEvalErrors( mAllowEvalErrors );
240
241 if ( !vl )
242 dlg.expressionBuilder()->expressionTree()->loadFieldNames( mFieldProxyModel->sourceFieldModel()->fields() );
243
244 if ( dlg.exec() )
245 {
246 const QString newExpression = dlg.expressionText();
247 setField( newExpression );
248 }
249}
250
256
258{
259 const QString expression = mCombo->lineEdit()->text();
260 mFieldProxyModel->sourceFieldModel()->setExpression( expression );
261 const QModelIndex idx = mFieldProxyModel->sourceFieldModel()->indexFromName( expression );
262 const QModelIndex proxyIndex = mFieldProxyModel->mapFromSource( idx );
263 mCombo->setCurrentIndex( proxyIndex.row() );
265}
266
268{
269 if ( event->type() == QEvent::EnabledChange )
270 {
272 }
273}
274
275void QgsFieldExpressionWidget::reloadLayer()
276{
277 setLayer( mFieldProxyModel->sourceFieldModel()->layer() );
278}
279
280void QgsFieldExpressionWidget::beforeResetModel()
281{
282 // Backup expression
283 mBackupExpression = mCombo->currentText();
284}
285
286void QgsFieldExpressionWidget::afterResetModel()
287{
288 // Restore expression
289 mCombo->lineEdit()->setText( mBackupExpression );
290}
291
292bool QgsFieldExpressionWidget::eventFilter( QObject *watched, QEvent *event )
293{
294 if ( watched == mCombo && event->type() == QEvent::KeyPress )
295 {
296 QKeyEvent *keyEvent = static_cast<QKeyEvent *>( event );
297 if ( keyEvent->key() == Qt::Key_Enter || keyEvent->key() == Qt::Key_Return )
298 {
300 return true;
301 }
302 }
303 return QObject::eventFilter( watched, event );
304}
305
307{
308 return mAllowEvalErrors;
309}
310
312{
313 if ( allowEvalErrors == mAllowEvalErrors )
314 return;
315
316 mAllowEvalErrors = allowEvalErrors;
318}
319
321{
323
324 bool isExpression, isValid;
325 const QString fieldName = currentField( &isExpression, &isValid );
326
327 // display tooltip if widget is shorter than expression
328 const QFontMetrics metrics( mCombo->lineEdit()->font() );
329 if ( metrics.boundingRect( fieldName ).width() > mCombo->lineEdit()->width() )
330 {
331 mCombo->setToolTip( fieldName );
332 }
333 else
334 {
335 mCombo->setToolTip( QString() );
336 }
337
338 emit fieldChanged( fieldName );
339 emit fieldChanged( fieldName, isValid );
340}
341
342void QgsFieldExpressionWidget::updateLineEditStyle( const QString &expression )
343{
344 QString stylesheet;
345 if ( !isEnabled() )
346 {
347 stylesheet = QStringLiteral( "QLineEdit { color: %1; }" ).arg( QColor( Qt::gray ).name() );
348 }
349 else
350 {
351 bool isExpression, isValid;
352 if ( !expression.isEmpty() )
353 {
354 isExpression = true;
355 isValid = isExpressionValid( expression );
356 }
357 else
358 {
359 currentField( &isExpression, &isValid );
360 }
361 QFont font = mCombo->lineEdit()->font();
362 font.setItalic( isExpression );
363 mCombo->lineEdit()->setFont( font );
364
365 if ( isExpression && !isValid )
366 {
367 stylesheet = QStringLiteral( "QLineEdit { color: %1; }" ).arg( QColor( Qt::red ).name() );
368 }
369 }
370 mCombo->lineEdit()->setStyleSheet( stylesheet );
371}
372
373bool QgsFieldExpressionWidget::isExpressionValid( const QString &expressionStr )
374{
375 QgsExpression expression( expressionStr );
376 expression.prepare( &mExpressionContext );
377 return !expression.hasParserError();
378}
379
381{
382 mExpressionContext.appendScope( scope );
383}
static QIcon getThemeIcon(const QString &name, const QColor &fillColor=QColor(), const QColor &strokeColor=QColor())
Helper to get a theme icon.
A general purpose distance and area calculator, capable of performing ellipsoid based calculations.
A generic dialog for building expression strings.
void setGeomCalculator(const QgsDistanceArea &da)
Sets geometry calculator used in distance/area calculations.
QgsExpressionBuilderWidget * expressionBuilder()
The builder widget that is used by the dialog.
void setAllowEvalErrors(bool allowEvalErrors)
Allow accepting expressions with evaluation errors.
QgsExpressionTreeView * expressionTree() const
Returns the expression tree.
Abstract interface for generating an expression context.
virtual QgsExpressionContext createExpressionContext() const =0
This method needs to be reimplemented in all classes which implement this interface and return an exp...
Single scope for storing variables and functions for use within a QgsExpressionContext.
static QgsExpressionContextScope * projectScope(const QgsProject *project)
Creates a new scope which contains variables and functions relating to a QGIS project.
static QgsExpressionContextScope * globalScope()
Creates a new scope which contains variables and functions relating to the global QGIS context.
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
void appendScope(QgsExpressionContextScope *scope)
Appends a scope to the end of the context.
void loadFieldNames(const QgsFields &fields)
This allows loading fields without specifying a layer.
Class for parsing and evaluation of expressions (formerly called "search strings").
static QString quotedColumnRef(QString name)
Returns a quoted column reference (in double quotes)
static bool checkExpression(const QString &text, const QgsExpressionContext *context, QString &errorMessage)
Tests whether a string is a valid expression.
void setExpressionDialogTitle(const QString &title)
define the title used in the expression dialog
void setAllowEmptyFieldName(bool allowEmpty)
Sets whether an optional empty field ("not set") option is shown in the combo box.
void setField(const QString &fieldName)
sets the current field or expression in the widget
bool isExpression() const
If the content is not just a simple field this method will return true.
QgsFieldExpressionWidget(QWidget *parent=nullptr)
QgsFieldExpressionWidget creates a widget with a combo box to display the fields and expression and a...
void expressionEdited(const QString &expression)
when expression is edited by the user in the line edit, it will be checked for validity
QString asExpression() const
Returns the currently selected field or expression.
void setExpression(const QString &expression)
Sets the current expression text and if applicable also the field.
void setGeomCalculator(const QgsDistanceArea &da)
Sets the geometry calculator used in the expression dialog.
bool isValidExpression(QString *expressionError=nullptr) const
Returns true if the current expression is valid.
bool isExpressionValid(const QString &expressionStr)
void setFields(const QgsFields &fields)
Sets the fields used in the widget to fields, this allows the widget to work without a layer.
void changeEvent(QEvent *event) override
QgsFieldProxyModel::Filters filters
QString expression() const
Returns the currently selected field or expression.
void setRow(int row)
sets the current row in the widget
QgsVectorLayer * layer() const
Returns the layer currently associated with the widget.
void editExpression()
open the expression dialog to edit the current or add a new expression
void appendScope(QgsExpressionContextScope *scope)
Appends a scope to the current expression context.
void expressionEditingFinished()
when expression has been edited (finished) it will be added to the model
void setLayer(QgsMapLayer *layer)
Sets the layer used to display the fields and expression.
void updateLineEditStyle(const QString &expression=QString())
updateLineEditStyle will re-style (color/font) the line edit depending on content and status
void registerExpressionContextGenerator(const QgsExpressionContextGenerator *generator)
Register an expression context generator class that will be used to retrieve an expression context fo...
void setAllowEvalErrors(bool allowEvalErrors)
Allow accepting expressions with evaluation errors.
void fieldChanged(const QString &fieldName)
Emitted when the currently selected field changes.
bool eventFilter(QObject *watched, QEvent *event) override
QString currentText() const
Returns the current text that is set in the expression area.
void setFilters(QgsFieldProxyModel::Filters filters)
setFilters allows filtering according to the type of field
void allowEvalErrorsChanged()
Allow accepting expressions with evaluation errors.
QString currentField(bool *isExpression=nullptr, bool *isValid=nullptr) const
currentField returns the currently selected field or expression if allowed
bool isField(const QString &expression) const
Returns true if a string represents a field reference, or false if it is an expression consisting of ...
void setAllowExpression(bool allowExpression)
Sets whether custom expressions are accepted and displayed in the model.
void setLayer(QgsVectorLayer *layer)
Set the layer from which fields are displayed.
void setExpression(const QString &expression)
Sets a single expression to be added after the fields at the end of the model.
QgsFields fields() const
Returns the fields currently shown in the model.
void setFields(const QgsFields &fields)
Manually sets the fields to use for the model.
bool allowEmptyFieldName
QgsVectorLayer * layer
QModelIndex indexFromName(const QString &fieldName)
Returns the index corresponding to a given fieldName.
void setAllowEmptyFieldName(bool allowEmpty)
Sets whether an optional empty field ("not set") option is present in the model.
The QgsFieldProxyModel class provides an easy to use model to display the list of fields of a layer.
QgsFieldModel * sourceFieldModel()
Returns the QgsFieldModel used in this QSortFilterProxyModel.
QgsFieldProxyModel * setFilters(QgsFieldProxyModel::Filters filters)
Set flags that affect how fields are filtered in the model.
Container of fields for a vector layer.
Definition qgsfields.h:45
Base class for all map layer types.
Definition qgsmaplayer.h:74
static QgsProject * instance()
Returns the QgsProject singleton instance.
QgsExpressionContext createExpressionContext() const override
This method needs to be reimplemented in all classes which implement this interface and return an exp...
Represents a vector layer which manages a vector based data sets.
QgsExpressionContext createExpressionContext() const FINAL
This method needs to be reimplemented in all classes which implement this interface and return an exp...
void updatedFields()
Emitted whenever the fields available from this layer have been changed.