QgsFields class

Container of fields for a vector layer.

Reference

In addition to storing a list of QgsField instances, it also:

allows quick lookups of field names to index in the list
keeps track of where the field definition comes from (vector data provider, joined layer or newly added from an editing operation)
Note
QgsFields objects are implicitly shared.

Public types

enum FieldOrigin { OriginUnknown, OriginProvider, OriginJoin, OriginEdit, OriginExpression }

Constructors, destructors, conversion operators

QgsFields(): Constructor for an empty field container.
QgsFields(const QgsFields& other): Copy constructor.
operator QVariant() const: Allows direct construction of QVariants from fields.

Public functions

auto allAttributesList() const -> QgsAttributeList: Utility function to get list of attribute indexes.
auto append(const QgsField& field, FieldOrigin origin = OriginProvider, int originIndex = -1) -> bool: Append a field. The field must have unique name, otherwise it is rejected (returns false)
auto appendExpressionField(const QgsField& field, int originIndex) -> bool: Append an expression field. The field must have unique name, otherwise it is rejected (returns false)
auto at(int i) const -> QgsField: Gets field at particular index (must be in range 0..N-1)
auto begin() const -> const_iterator noexcept: Returns a const STL-style iterator pointing to the first item in the list.
auto begin() -> iterator: Returns an STL-style iterator pointing to the first item in the list.
void clear(): Remove all fields.
auto constBegin() const -> const_iterator noexcept: Returns a const STL-style iterator pointing to the first item in the list.
auto constEnd() const -> const_iterator noexcept: Returns a const STL-style iterator pointing to the imaginary item after the last item in the list.
auto count() const -> int: Returns number of items.
auto end() const -> const_iterator noexcept: Returns a const STL-style iterator pointing to the imaginary item after the last item in the list.
auto end() -> iterator: Returns an STL-style iterator pointing to the imaginary item after the last item in the list.
auto exists(int i) const -> bool: Returns if a field index is valid.
void extend(const QgsFields& other): Extend with fields from another QgsFields container.
auto field(int fieldIdx) const -> QgsField: Gets field at particular index (must be in range 0..N-1)
auto field(const QString& name) const -> QgsField: Gets field with matching name.
auto fieldOrigin(int fieldIdx) const -> FieldOrigin: Gets field's origin (value from an enumeration)
auto fieldOriginIndex(int fieldIdx) const -> int: Gets field's origin index (its meaning is specific to each type of origin)
auto iconForField(int fieldIdx) const -> QIcon: Returns an icon corresponding to a field index, based on the field's type and source.
auto indexFromName(const QString& fieldName) const -> int: Gets the field index from the field name.
auto indexOf(const QString& fieldName) const -> int: Gets the field index from the field name.
auto isEmpty() const -> bool: Check whether the container is empty.
auto lookupField(const QString& fieldName) const -> int: Look up field's index from the field name.
auto names() const -> QStringList: Returns a list with field names.
auto operator!=(const QgsFields& other) const -> bool
auto operator=(const QgsFields& other) -> QgsFields&: Assignment operator.
auto operator==(const QgsFields& other) const -> bool
auto operator[](int i) const -> QgsField: Gets field at particular index (must be in range 0..N-1)
auto operator[](int i) -> QgsField&: Gets field at particular index (must be in range 0..N-1)
void remove(int fieldIdx): Remove a field with the given index.
auto size() const -> int: Returns number of items.
auto toList() const -> QList<QgsField>: Utility function to return a list of QgsField instances.

Enum documentation

enum QgsFields::FieldOrigin

Enumerators
OriginUnknown	It has not been specified where the field comes from.
OriginProvider	Field comes from the underlying data provider of the vector layer (originIndex = index in provider's fields)
OriginJoin	Field comes from a joined layer (originIndex / 1000 = index of the join, originIndex % 1000 = index within the join)
OriginEdit	Field has been temporarily added in editing mode (originIndex = index in the list of added attributes)
OriginExpression	Field is calculated from an expression.

Function documentation

QgsAttributeList QgsFields::allAttributesList() const

Utility function to get list of attribute indexes.

const_iterator QgsFields::begin() const noexcept

Returns a const STL-style iterator pointing to the first item in the list.

iterator QgsFields::begin()

Returns an STL-style iterator pointing to the first item in the list.

const_iterator QgsFields::constBegin() const noexcept

Returns a const STL-style iterator pointing to the first item in the list.

const_iterator QgsFields::constEnd() const noexcept

Returns a const STL-style iterator pointing to the imaginary item after the last item in the list.

const_iterator QgsFields::end() const noexcept

Returns a const STL-style iterator pointing to the imaginary item after the last item in the list.

iterator QgsFields::end()

Returns an STL-style iterator pointing to the imaginary item after the last item in the list.

bool QgsFields::exists(int i) const

Returns if a field index is valid.

Parameters
i	Index of the field which needs to be checked
Returns	True if the field exists

QIcon QgsFields::iconForField(int fieldIdx) const

Returns an icon corresponding to a field index, based on the field's type and source.

int QgsFields::indexFromName(const QString& fieldName) const

Gets the field index from the field name.

Parameters
fieldName	The name of the field.
Returns	The field index if found or -1 in case it cannot be found.

This method is case sensitive and only matches the data source name of the field. Alias for indexOf

int QgsFields::indexOf(const QString& fieldName) const