QgsFieldModel class

The QgsFieldModel class is a model to display the list of fields of a layer in widgets.

Reference

If allowed, expressions might be added to the end of the model. It can be associated with a QgsMapLayerModel to dynamically display a layer and its fields.

Public types

enum FieldRoles { FieldNameRole = Qt::UserRole + 1, FieldIndexRole = Qt::UserRole + 2, ExpressionRole = Qt::UserRole + 3, IsExpressionRole = Qt::UserRole + 4, ExpressionValidityRole = Qt::UserRole + 5, FieldTypeRole = Qt::UserRole + 6, FieldOriginRole = Qt::UserRole + 7, IsEmptyRole = Qt::UserRole + 8 }: Roles utilized by the model.

Public static functions

static auto fieldToolTip(const QgsField& field) -> QString: Returns a HTML formatted tooltip string for a field, containing details like the field name, alias and type.

Constructors, destructors, conversion operators

QgsFieldModel(QObject* parent = nullptr) explicit: Constructor for QgsFieldModel - creates a model to display the fields of a given layer.

Public functions

auto allowEmptyFieldName() const -> bool: Returns true if the model allows the empty field ("not set") choice.
auto allowExpression() -> bool: Returns true if the model allows custom expressions to be created and displayed.
auto indexFromName(const QString& fieldName) -> QModelIndex: Returns the index corresponding to a given fieldName.
auto isField(const QString& expression) const -> bool: Returns true if a string represents a field reference, or false if it is an expression consisting of more than direct field reference.
auto layer() -> QgsVectorLayer*: Returns the layer associated with the model.
void removeExpression(): Removes any custom expression from the model.
void setAllowEmptyFieldName(bool allowEmpty): Sets whether an optional empty field ("not set") option is present in the model.
void setAllowExpression(bool allowExpression): Sets whether custom expressions are accepted and displayed in the model.
void setExpression(const QString& expression): Sets a single expression to be added after the fields at the end of the model.

Public slots

void setLayer(QgsVectorLayer* layer): Set the layer from which fields are displayed.

Protected slots

void updateModel() virtual: Called when the model must be updated.

Enum documentation

enum QgsFieldModel::FieldRoles

Roles utilized by the model.

Enumerators
FieldNameRole	Return field name if index corresponds to a field.
FieldIndexRole	Return field index if index corresponds to a field.
ExpressionRole	Return field name or expression.
IsExpressionRole	Return if index corresponds to an expression.
ExpressionValidityRole	Return if expression is valid or not.
FieldTypeRole	Return the field type (if a field, return QVariant if expression)
FieldOriginRole	Return the field origin (if a field, returns QVariant if expression)
IsEmptyRole	Return if the index corresponds to the empty value.

Function documentation

static QString QgsFieldModel::fieldToolTip(const QgsField& field)

Returns a HTML formatted tooltip string for a field, containing details like the field name, alias and type.

bool QgsFieldModel::allowEmptyFieldName() const

Returns true if the model allows the empty field ("not set") choice.

bool QgsFieldModel::allowExpression()

Returns true if the model allows custom expressions to be created and displayed.

QgsVectorLayer* QgsFieldModel::layer()

Returns the layer associated with the model.

void QgsFieldModel::removeExpression()

Removes any custom expression from the model.

void QgsFieldModel::setAllowEmptyFieldName(bool allowEmpty)

Sets whether an optional empty field ("not set") option is present in the model.

void QgsFieldModel::setAllowExpression(bool allowExpression)

Sets whether custom expressions are accepted and displayed in the model.

void QgsFieldModel::setExpression(const QString& expression)

Sets a single expression to be added after the fields at the end of the model.

void QgsFieldModel::setLayer(QgsVectorLayer* layer) public slot

Set the layer from which fields are displayed.