QGIS API Documentation 3.36.0-Maidenhead (09951dc0acf)
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Contains utility methods for working with QgsVectorLayers. More...
#include <qgsvectorlayerutils.h>
Classes | |
class | QgsDuplicateFeatureContext |
Contains mainly the QMap with QgsVectorLayer and QgsFeatureIds do list all the duplicated features. More... | |
class | QgsFeatureData |
Encapsulate geometry and attributes for new features, to be passed to createFeatures. More... | |
Public Types | |
enum | CascadedFeatureFlag { IgnoreAuxiliaryLayers = 1 << 1 } |
Flags that can be used when determining cascaded features. More... | |
typedef QList< QgsVectorLayerUtils::QgsFeatureData > | QgsFeaturesDataList |
Alias for list of QgsFeatureData. | |
Static Public Member Functions | |
static bool | attributeHasConstraints (const QgsVectorLayer *layer, int attributeIndex) |
Returns true if a feature attribute has active constraints. | |
static QgsFeature | createFeature (const QgsVectorLayer *layer, const QgsGeometry &geometry=QgsGeometry(), const QgsAttributeMap &attributes=QgsAttributeMap(), QgsExpressionContext *context=nullptr) |
Creates a new feature ready for insertion into a layer. | |
static QgsFeatureList | createFeatures (const QgsVectorLayer *layer, const QgsFeaturesDataList &featuresData, QgsExpressionContext *context=nullptr) |
Creates a set of new features ready for insertion into a layer. | |
static QVariant | createUniqueValue (const QgsVectorLayer *layer, int fieldIndex, const QVariant &seed=QVariant()) |
Returns a new attribute value for the specified field index which is guaranteed to be unique. | |
static QVariant | createUniqueValueFromCache (const QgsVectorLayer *layer, int fieldIndex, const QSet< QVariant > &existingValues, const QVariant &seed=QVariant()) |
Returns a new attribute value for the specified field index which is guaranteed to be unique within regard to existingValues. | |
static QgsFeature | duplicateFeature (QgsVectorLayer *layer, const QgsFeature &feature, QgsProject *project, QgsDuplicateFeatureContext &duplicateFeatureContext, const int maxDepth=0, int depth=0, QList< QgsVectorLayer * > referencedLayersBranch=QList< QgsVectorLayer * >()) |
Duplicates a feature and it's children (one level deep). | |
static bool | fieldEditabilityDependsOnFeature (const QgsVectorLayer *layer, int fieldIndex) |
Returns true if the editability of the field at index fieldIndex from layer may vary feature by feature. | |
static bool | fieldIsEditable (const QgsVectorLayer *layer, int fieldIndex, const QgsFeature &feature) |
Tests whether a field is editable for a particular feature. | |
static bool | fieldIsReadOnly (const QgsVectorLayer *layer, int fieldIndex) |
static QList< double > | getDoubleValues (const QgsVectorLayer *layer, const QString &fieldOrExpression, bool &ok, bool selectedOnly=false, int *nullCount=nullptr, QgsFeedback *feedback=nullptr) |
Fetches all double values from a specified field name or expression. | |
static QString | getFeatureDisplayString (const QgsVectorLayer *layer, const QgsFeature &feature) |
static std::unique_ptr< QgsVectorLayerFeatureSource > | getFeatureSource (QPointer< QgsVectorLayer > layer, QgsFeedback *feedback=nullptr) |
Gets the feature source from a QgsVectorLayer pointer. | |
static QList< QVariant > | getValues (const QgsVectorLayer *layer, const QString &fieldOrExpression, bool &ok, bool selectedOnly=false, QgsFeedback *feedback=nullptr) |
Fetches all values from a specified field name or expression. | |
static QgsFeatureIterator | getValuesIterator (const QgsVectorLayer *layer, const QString &fieldOrExpression, bool &ok, bool selectedOnly) |
Create a feature iterator for a specified field name or expression. | |
static QString | guessFriendlyIdentifierField (const QgsFields &fields, bool *foundFriendly=nullptr) |
Given a set of fields, attempts to pick the "most useful" field for user-friendly identification of features. | |
static bool | impactsCascadeFeatures (const QgsVectorLayer *layer, const QgsFeatureIds &fids, const QgsProject *project, QgsDuplicateFeatureContext &context, QgsVectorLayerUtils::CascadedFeatureFlags flags=QgsVectorLayerUtils::CascadedFeatureFlags()) |
static QHash< QString, QgsMaskedLayers > | labelMasks (const QgsVectorLayer *) |
Returns masks defined in labeling options of a layer. | |
static QgsFeatureList | makeFeatureCompatible (const QgsFeature &feature, const QgsVectorLayer *layer, QgsFeatureSink::SinkFlags sinkFlags=QgsFeatureSink::SinkFlags()) |
Converts input feature to be compatible with the given layer. | |
static QgsFeatureList | makeFeaturesCompatible (const QgsFeatureList &features, const QgsVectorLayer *layer, QgsFeatureSink::SinkFlags sinkFlags=QgsFeatureSink::SinkFlags()) |
Converts input features to be compatible with the given layer. | |
static void | matchAttributesToFields (QgsFeature &feature, const QgsFields &fields) |
Matches the attributes in feature to the specified fields. | |
static QgsMaskedLayers | symbolLayerMasks (const QgsVectorLayer *) |
Returns all masks that may be defined on symbol layers for a given vector layer. | |
static bool | validateAttribute (const QgsVectorLayer *layer, const QgsFeature &feature, int attributeIndex, QStringList &errors, QgsFieldConstraints::ConstraintStrength strength=QgsFieldConstraints::ConstraintStrengthNotSet, QgsFieldConstraints::ConstraintOrigin origin=QgsFieldConstraints::ConstraintOriginNotSet) |
Tests a feature attribute value to check whether it passes all constraints which are present on the corresponding field. | |
static bool | valueExists (const QgsVectorLayer *layer, int fieldIndex, const QVariant &value, const QgsFeatureIds &ignoreIds=QgsFeatureIds()) |
Returns true if the specified value already exists within a field. | |
Contains utility methods for working with QgsVectorLayers.
Definition at line 51 of file qgsvectorlayerutils.h.
Alias for list of QgsFeatureData.
Definition at line 118 of file qgsvectorlayerutils.h.
Flags that can be used when determining cascaded features.
Enumerator | |
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IgnoreAuxiliaryLayers | Ignore auxiliary layers. |
Definition at line 377 of file qgsvectorlayerutils.h.
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Returns true
if a feature attribute has active constraints.
layer | the vector layer from which field constraints will be checked for |
attributeIndex | the attribute index |
Definition at line 370 of file qgsvectorlayerutils.cpp.
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Creates a new feature ready for insertion into a layer.
Default values and constraints (e.g., unique constraints) will automatically be handled. An optional attribute map can be passed for the new feature to copy as many attribute values as possible from the map, assuming that they respect the layer's constraints. Note that the created feature is not automatically inserted into the layer.
Definition at line 485 of file qgsvectorlayerutils.cpp.
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Creates a set of new features ready for insertion into a layer.
Default values and constraints (e.g., unique constraints) will automatically be handled. Note that the created features are not automatically inserted into the layer.
Definition at line 492 of file qgsvectorlayerutils.cpp.
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Returns a new attribute value for the specified field index which is guaranteed to be unique.
The optional seed value can be used as a basis for generated values.
Definition at line 209 of file qgsvectorlayerutils.cpp.
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Returns a new attribute value for the specified field index which is guaranteed to be unique within regard to existingValues.
The optional seed value can be used as a basis for generated values.
Definition at line 289 of file qgsvectorlayerutils.cpp.
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Duplicates a feature and it's children (one level deep).
It calls CreateFeature, so default values and constraints (e.g., unique constraints) will automatically be handled. The duplicated feature will be automatically inserted into the layer. duplicateFeatureContext stores all the layers and the featureids of the duplicated features (incl. children) maxDepth the maximum depth to duplicate children in relations, 0 is unlimited depth (in any case, limited to 100) depth the current depth, not exposed in Python referencedLayersBranch the current branch of layers across the relations, not exposed in Python, taken by copy not reference, used to avoid infinite loop
Definition at line 634 of file qgsvectorlayerutils.cpp.
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Returns true
if the editability of the field at index fieldIndex from layer may vary feature by feature.
I.e. if the field is taken from a joined layer, the value may or may not be editable for any individual feature depending on the join's "upsert on edit" capabilities.
Definition at line 903 of file qgsvectorlayerutils.cpp.
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Tests whether a field is editable for a particular feature.
true
if the field at index fieldIndex from layer is editable, false
if the field is read only.Definition at line 924 of file qgsvectorlayerutils.cpp.
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true
if the field at index fieldIndex from layer is editable, false
if the field is read only.If this function returns true
then the editability of the field may still vary feature by feature. See fieldIsEditable() to determine this on a feature by feature basis.
Definition at line 876 of file qgsvectorlayerutils.cpp.
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Fetches all double values from a specified field name or expression.
Null values or invalid expression results are skipped.
layer | vector layer to retrieve values from |
fieldOrExpression | field name or an expression string evaluating to a double value |
ok | will be set to false if field or expression is invalid, otherwise true |
selectedOnly | set to true to get values from selected features only |
nullCount | optional pointer to integer to store number of null values encountered in |
feedback | optional feedback object to allow cancellation |
Definition at line 122 of file qgsvectorlayerutils.cpp.
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displayExpression
property of layer. Definition at line 1058 of file qgsvectorlayerutils.cpp.
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Gets the feature source from a QgsVectorLayer pointer.
This method is thread-safe but will block the main thread for execution. Executing it from the main thread is safe too. This should be used in scenarios, where a QWeakPointer<QgsVectorLayer>
is kept in a thread and features should be fetched from this layer. Using the layer directly is not safe to do. The result will be \c nullptr
if the layer has been deleted. If feedback is specified, the call will return if the feedback is canceled. Returns a new feature source for the layer. The source may be nullptr
if the layer no longer exists or if the feedback is canceled.
Definition at line 686 of file qgsvectorlayerutils.cpp.
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Fetches all values from a specified field name or expression.
layer | vector layer to retrieve values from |
fieldOrExpression | field name or an expression string |
ok | will be set to false if field or expression is invalid, otherwise true |
selectedOnly | set to true to get values from selected features only |
feedback | optional feedback object to allow cancellation |
Definition at line 82 of file qgsvectorlayerutils.cpp.
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Create a feature iterator for a specified field name or expression.
layer | vector layer to retrieve values from |
fieldOrExpression | field name or an expression string |
ok | will be set to false if field or expression is invalid, otherwise true |
selectedOnly | set to true to get values from selected features only |
Definition at line 40 of file qgsvectorlayerutils.cpp.
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Given a set of fields, attempts to pick the "most useful" field for user-friendly identification of features.
For instance, if a field called "name" is present, this will be returned.
Assumes that the user has organized the data with the more "interesting" field names first. As such, "name" would be selected before "oldname", "othername", etc.
If no friendly identifier is found, the function will fallback to the first available.
An optional boolean parameter can be used to determine whether the returned field name is a friendly identifier or not.
fields | list of fields to pick a friendly identifier from |
foundFriendly | set to true if the returned field name is a friendly identifier (since QGIS 3.22) |
Definition at line 1160 of file qgsvectorlayerutils.cpp.
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true
if at least one feature of the fids on layer is connected as parent in at least one composition relation of the project or contains joins, where cascade delete is set. Details about cascading effects will be written to context. Definition at line 1070 of file qgsvectorlayerutils.cpp.
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Returns masks defined in labeling options of a layer.
The returned type associates a labeling rule identifier to a set of layers that are masked given by their layer id, and a set of masked symbol layers if associated to each masked layers.
Definition at line 949 of file qgsvectorlayerutils.cpp.
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Converts input feature to be compatible with the given layer.
This function returns a new list of transformed features compatible with the input layer, note that the number of features returned might be greater than one when converting a multi part geometry to single part
The following operations will be performed to convert the input features:
Optionally, sinkFlags can be specified to further refine the compatibility logic.
Definition at line 745 of file qgsvectorlayerutils.cpp.
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Converts input features to be compatible with the given layer.
This function returns a new list of transformed features compatible with the input layer, note that the number of features returned might be greater than the number of input features.
The following operations will be performed to convert the input features:
Optionally, sinkFlags can be specified to further refine the compatibility logic.
Definition at line 807 of file qgsvectorlayerutils.cpp.
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Matches the attributes in feature to the specified fields.
This causes the attributes contained within the given feature to be rearranged (or in some cases dropped) in order to match the fields and order indicated by fields.
The exact behavior depends on whether or not feature has a valid fields container set (see QgsFeature::fields()). If a fields container is set, then the names of the feature's fields are matched to fields. In this case attributes from feature will be rearranged or dropped in order to match the field names from fields.
If the feature does not have a valid fields container set, then the feature's attributes are simply truncated to match the number of fields present in fields (or if less attributes are present in feature than in fields, the feature's attributes are padded with NULL values to match the required length). Finally, the feature's fields are set to fields.
Definition at line 706 of file qgsvectorlayerutils.cpp.
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Returns all masks that may be defined on symbol layers for a given vector layer.
The hash key is a layer id. The hash value is the set of symbol layers masked in the key's layer.
Definition at line 999 of file qgsvectorlayerutils.cpp.
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Tests a feature attribute value to check whether it passes all constraints which are present on the corresponding field.
Returns true
if the attribute value is valid for the field. Any constraint failures will be reported in the errors argument. If the strength or origin parameter is set then only constraints with a matching strength/origin will be checked.
Definition at line 384 of file qgsvectorlayerutils.cpp.
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Returns true
if the specified value already exists within a field.
This method can be used to test for uniqueness of values inside a layer's attributes. An optional list of ignored feature IDs can be provided, if so, any features with IDs within this list are ignored when testing for existence of the value.
Definition at line 154 of file qgsvectorlayerutils.cpp.