QGIS API Documentation  3.25.0-Master (6b426f5f8a)
qgsfieldexpressionwidget.cpp
Go to the documentation of this file.
1 
2 /***************************************************************************
3  qgsfieldexpressionwidget.cpp
4  --------------------------------------
5  Date : 01.04.2014
6  Copyright : (C) 2014 Denis Rouzaud
7  Email : [email protected]
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  // give focus to the combo
59  // hence if the widget is used as a delegate
60  // it will allow pressing on the expression dialog button
61  setFocusProxy( mCombo );
62 
63  connect( mCombo->lineEdit(), &QLineEdit::textEdited, this, &QgsFieldExpressionWidget::expressionEdited );
64  connect( mCombo->lineEdit(), &QLineEdit::editingFinished, this, &QgsFieldExpressionWidget::expressionEditingFinished );
65  connect( mCombo, static_cast < void ( QComboBox::* )( int ) > ( &QComboBox::activated ), this, &QgsFieldExpressionWidget::currentFieldChanged );
66  connect( mButton, &QAbstractButton::clicked, this, &QgsFieldExpressionWidget::editExpression );
67  connect( mFieldProxyModel, &QAbstractItemModel::modelAboutToBeReset, this, &QgsFieldExpressionWidget::beforeResetModel );
68  connect( mFieldProxyModel, &QAbstractItemModel::modelReset, this, &QgsFieldExpressionWidget::afterResetModel );
69 
70  mExpressionContext = QgsExpressionContext();
71  mExpressionContext << QgsExpressionContextUtils::globalScope()
73 
74  mCombo->installEventFilter( this );
75 }
76 
78 {
79  mExpressionDialogTitle = title;
80 }
81 
82 void QgsFieldExpressionWidget::setFilters( QgsFieldProxyModel::Filters filters )
83 {
84  mFieldProxyModel->setFilters( filters );
85 }
86 
88 {
89  mCombo->lineEdit()->setClearButtonEnabled( allowEmpty );
90  mFieldProxyModel->sourceFieldModel()->setAllowEmptyFieldName( allowEmpty );
91 }
92 
94 {
95  return mFieldProxyModel->sourceFieldModel()->allowEmptyFieldName();
96 }
97 
99 {
100  QHBoxLayout *layout = dynamic_cast<QHBoxLayout *>( this->layout() );
101  if ( !layout )
102  return;
103 
104  if ( isLeft )
105  {
106  QLayoutItem *item = layout->takeAt( 1 );
107  layout->insertWidget( 0, item->widget() );
108  }
109  else
110  layout->addWidget( mCombo );
111 }
112 
114 {
115  mDistanceArea = std::shared_ptr<const QgsDistanceArea>( new QgsDistanceArea( da ) );
116 }
117 
119 {
120  return mCombo->currentText();
121 }
122 
124 {
126 }
127 
129 {
130  return asExpression();
131 }
132 
133 bool QgsFieldExpressionWidget::isValidExpression( QString *expressionError ) const
134 {
135  QString temp;
136  return QgsExpression::checkExpression( currentText(), &mExpressionContext, expressionError ? *expressionError : temp );
137 }
138 
140 {
141  return !mFieldProxyModel->sourceFieldModel()->isField( currentText() );
142 }
143 
144 QString QgsFieldExpressionWidget::currentField( bool *isExpression, bool *isValid ) const
145 {
146  QString text = currentText();
147  const bool valueIsExpression = this->isExpression();
148  if ( isValid )
149  {
150  // valid if not an expression (ie, set to a field), or set to an expression and expression is valid
151  *isValid = !valueIsExpression || isValidExpression();
152  }
153  if ( isExpression )
154  {
155  *isExpression = valueIsExpression;
156  }
157  return text;
158 }
159 
161 {
162  return mFieldProxyModel->sourceFieldModel()->layer();
163 }
164 
166 {
167  mExpressionContextGenerator = generator;
168 }
169 
171 {
172  QgsVectorLayer *vl = qobject_cast< QgsVectorLayer * >( layer );
173 
174  if ( mFieldProxyModel->sourceFieldModel()->layer() )
175  disconnect( mFieldProxyModel->sourceFieldModel()->layer(), &QgsVectorLayer::updatedFields, this, &QgsFieldExpressionWidget::reloadLayer );
176 
177  if ( vl )
178  mExpressionContext = vl->createExpressionContext();
179  else
180  mExpressionContext = QgsProject::instance()->createExpressionContext();
181 
182  mFieldProxyModel->sourceFieldModel()->setLayer( vl );
183 
184  if ( mFieldProxyModel->sourceFieldModel()->layer() )
185  connect( mFieldProxyModel->sourceFieldModel()->layer(), &QgsVectorLayer::updatedFields, this, &QgsFieldExpressionWidget::reloadLayer, Qt::UniqueConnection );
186 }
187 
188 void QgsFieldExpressionWidget::setField( const QString &fieldName )
189 {
190  if ( fieldName.isEmpty() )
191  {
192  setRow( -1 );
193  emit fieldChanged( QString() );
194  emit fieldChanged( QString(), true );
195  return;
196  }
197 
198  QModelIndex idx = mFieldProxyModel->sourceFieldModel()->indexFromName( fieldName );
199  if ( !idx.isValid() )
200  {
201  // try to remove quotes and white spaces
202  QString simpleFieldName = fieldName.trimmed();
203  if ( simpleFieldName.startsWith( '"' ) && simpleFieldName.endsWith( '"' ) )
204  {
205  simpleFieldName.remove( 0, 1 ).chop( 1 );
206  idx = mFieldProxyModel->sourceFieldModel()->indexFromName( simpleFieldName );
207  }
208 
209  if ( !idx.isValid() )
210  {
211  // new expression
212  mFieldProxyModel->sourceFieldModel()->setExpression( fieldName );
213  idx = mFieldProxyModel->sourceFieldModel()->indexFromName( fieldName );
214  }
215  }
216  const QModelIndex proxyIndex = mFieldProxyModel->mapFromSource( idx );
217  mCombo->setCurrentIndex( proxyIndex.row() );
219 }
220 
222 {
223  mFieldProxyModel->sourceFieldModel()->setFields( fields );
224 }
225 
226 void QgsFieldExpressionWidget::setExpression( const QString &expression )
227 {
228  setField( expression );
229 }
230 
232 {
233  const QString currentExpression = asExpression();
234  QgsVectorLayer *vl = layer();
235 
236  const QgsExpressionContext context = mExpressionContextGenerator ? mExpressionContextGenerator->createExpressionContext() : mExpressionContext;
237 
238  QgsExpressionBuilderDialog dlg( vl, currentExpression, this, QStringLiteral( "generic" ), context );
239  if ( mDistanceArea )
240  {
241  dlg.setGeomCalculator( *mDistanceArea );
242  }
243  dlg.setWindowTitle( mExpressionDialogTitle );
244  dlg.setAllowEvalErrors( mAllowEvalErrors );
245 
246  if ( !vl )
247  dlg.expressionBuilder()->expressionTree()->loadFieldNames( mFieldProxyModel->sourceFieldModel()->fields() );
248 
249  if ( dlg.exec() )
250  {
251  const QString newExpression = dlg.expressionText();
252  setField( newExpression );
253  }
254 }
255 
256 void QgsFieldExpressionWidget::expressionEdited( const QString &expression )
257 {
260 }
261 
263 {
264  const QString expression = mCombo->lineEdit()->text();
265  mFieldProxyModel->sourceFieldModel()->setExpression( expression );
266  const QModelIndex idx = mFieldProxyModel->sourceFieldModel()->indexFromName( expression );
267  const QModelIndex proxyIndex = mFieldProxyModel->mapFromSource( idx );
268  mCombo->setCurrentIndex( proxyIndex.row() );
270 }
271 
273 {
274  if ( event->type() == QEvent::EnabledChange )
275  {
277  }
278 }
279 
280 void QgsFieldExpressionWidget::reloadLayer()
281 {
282  setLayer( mFieldProxyModel->sourceFieldModel()->layer() );
283 }
284 
285 void QgsFieldExpressionWidget::beforeResetModel()
286 {
287  // Backup expression
288  mBackupExpression = mCombo->currentText();
289 }
290 
291 void QgsFieldExpressionWidget::afterResetModel()
292 {
293  // Restore expression
294  mCombo->lineEdit()->setText( mBackupExpression );
295 }
296 
297 bool QgsFieldExpressionWidget::eventFilter( QObject *watched, QEvent *event )
298 {
299  if ( watched == mCombo && event->type() == QEvent::KeyPress )
300  {
301  QKeyEvent *keyEvent = static_cast<QKeyEvent *>( event );
302  if ( keyEvent->key() == Qt::Key_Enter || keyEvent->key() == Qt::Key_Return )
303  {
305  return true;
306  }
307  }
308  return QObject::eventFilter( watched, event );
309 }
310 
312 {
313  return mAllowEvalErrors;
314 }
315 
317 {
318  if ( allowEvalErrors == mAllowEvalErrors )
319  return;
320 
321  mAllowEvalErrors = allowEvalErrors;
322  emit allowEvalErrorsChanged();
323 }
324 
326 {
328 
329  bool isExpression, isValid;
330  const QString fieldName = currentField( &isExpression, &isValid );
331 
332  // display tooltip if widget is shorter than expression
333  const QFontMetrics metrics( mCombo->lineEdit()->font() );
334  if ( metrics.boundingRect( fieldName ).width() > mCombo->lineEdit()->width() )
335  {
336  mCombo->setToolTip( fieldName );
337  }
338  else
339  {
340  mCombo->setToolTip( QString() );
341  }
342 
343  emit fieldChanged( fieldName );
344  emit fieldChanged( fieldName, isValid );
345 }
346 
347 void QgsFieldExpressionWidget::updateLineEditStyle( const QString &expression )
348 {
349  QString stylesheet;
350  if ( !isEnabled() )
351  {
352  stylesheet = QStringLiteral( "QLineEdit { color: %1; }" ).arg( QColor( Qt::gray ).name() );
353  }
354  else
355  {
356  bool isExpression, isValid;
357  if ( !expression.isEmpty() )
358  {
359  isExpression = true;
360  isValid = isExpressionValid( expression );
361  }
362  else
363  {
364  currentField( &isExpression, &isValid );
365  }
366  QFont font = mCombo->lineEdit()->font();
367  font.setItalic( isExpression );
368  mCombo->lineEdit()->setFont( font );
369 
370  if ( isExpression && !isValid )
371  {
372  stylesheet = QStringLiteral( "QLineEdit { color: %1; }" ).arg( QColor( Qt::red ).name() );
373  }
374  }
375  mCombo->lineEdit()->setStyleSheet( stylesheet );
376 }
377 
378 bool QgsFieldExpressionWidget::isExpressionValid( const QString &expressionStr )
379 {
380  QgsExpression expression( expressionStr );
381  expression.prepare( &mExpressionContext );
382  return !expression.hasParserError();
383 }
384 
386 {
387  mExpressionContext.appendScope( scope );
388 }
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
Definition: qgsfieldmodel.h:43
QgsVectorLayer * layer
Definition: qgsfieldmodel.h:44
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:73
static QgsProject * instance()
Returns the QgsProject singleton instance.
Definition: qgsproject.cpp:472
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.