Class: QgsDataProvider¶
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class
qgis.core.
QgsDataProvider
(uri: str = '', options: QgsDataProvider.ProviderOptions = QgsDataProvider.ProviderOptions())¶ Bases:
PyQt5.QtCore.QObject
Create a new dataprovider with the specified in the
uri
.Additional creation options are specified within the
options
value.Abstract base class for spatial data provider implementations.
Enums
Methods
Add error message
Returns the coordinate system for the data source.
Gets the data source specification.
Current time stamp of data source
Returns description
Enter update mode.
Gets current status error.
Returns the extent of the layer
Returns raster file filter string
Returns vector file filter string
Invalidate connections corresponding to specified name
Returns true if this is a valid layer.
Returns layer metadata collected from the provider’s source.
Leave update mode.
Returns a provider name
Gets the current value of a certain provider property.
Reloads the data from the source.
Set the data source specification.
Sets error message
Reorder the list of layer names to be rendered by this provider (in order from bottom to top)
Set whether the provider will listen to datasource notifications If set, the provider will issue notify signals.
Allows setting arbitrary properties on the provider.
Set the visibility of the given sublayer name
Set the subset string used to create a subset of features in the layer.
Set the data source specification.
Returns the number of layers for the current data source
Sub-layer styles for each sub-layer handled by this provider, in order from bottom to top
Sub-layers handled by this provider, in order from bottom to top
Returns the subset definition string (typically sql) currently in use by the layer and used by the provider to limit the feature set.
Returns true if the provider supports setting of subset strings.
Time stamp of data source in the moment when data/metadata were loaded by provider
Update the extents of the layer.
Gets the data source specification.
Writes layer
metadata
to the underlying provider source.Signals
Emitted whenever a change is made to the data provider which may have caused changes in the provider’s data OUTSIDE of QGIS.
Emitted whenever a deferred extent calculation is completed by the provider.
Emitted when the datasource issues a notification.
Attributes
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CustomData
= 3000¶
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class
DataCapability
¶ Bases:
int
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baseClass
¶ alias of
QgsDataProvider
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Database
= 4¶
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Dir
= 2¶
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EvaluateDefaultValues
= 0¶
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File
= 1¶
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Net
= 8¶
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NoDataCapabilities
= 0¶
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class
ProviderOptions
¶ Bases:
sip.wrapper
QgsDataProvider.ProviderOptions(QgsDataProvider.ProviderOptions)
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unused
¶
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class
ProviderProperty
¶ Bases:
int
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SUBLAYER_SEPARATOR
= '!!::!!'¶
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appendError
(self, message: QgsErrorMessage)¶ Add error message
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childEvent
()¶
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connectNotify
()¶
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crs
(self) → QgsCoordinateReferenceSystem¶ Returns the coordinate system for the data source. If the provider isn’t capable of returning its projection then an invalid QgsCoordinateReferenceSystem will be returned.
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customEvent
()¶
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dataChanged
¶ Emitted whenever a change is made to the data provider which may have caused changes in the provider’s data OUTSIDE of QGIS.
When emitted from a
QgsVectorDataProvider
, any cached information such as feature ids should be invalidated.Warning
This signal is NOT emitted when changes are made to a provider from INSIDE QGIS – e.g. when adding features to a vector layer, deleting features or modifying existing features. Instead, the specific QgsVectorLayer signals should be used to detect these operations. [signal]
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dataSourceUri
(self, expandAuthConfig: bool = False) → str¶ Gets the data source specification. This may be a path or database connection string
- Parameters
expandAuthConfig – Whether to expand any assigned authentication configuration
- Returns
data source specification
Note
The default authentication configuration expansion is FALSE. This keeps credentials out of layer data source URIs and project files. Expansion should be specifically done only when needed within a provider
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dataTimestamp
(self) → QDateTime¶ Current time stamp of data source
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description
(self) → str¶ Returns description
Returns a terse string describing what the provider is.
note
Instead of being pure virtual, might be better to generalize this behavior and presume that none of the sub-classes are going to do anything strange with regards to their name or description?
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disconnectNotify
()¶
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enterUpdateMode
(self) → bool¶ Enter update mode.
This is aimed at providers that can open differently the connection to the datasource, according it to be in update mode or in read-only mode. A call to this method shall be balanced with a call to leaveUpdateMode(), if this method returns true.
Most providers will have an empty implementation for that method.
For backward compatibility, providers that implement enterUpdateMode() should still make sure to allow editing operations to work even if enterUpdateMode() is not explicitly called.
Several successive calls to enterUpdateMode() can be done. So there is a concept of stack of calls that must be handled by the provider. Only the first call to enterUpdateMode() will really turn update mode on.
- Returns
true in case of success (or no-op implementation), false in case of failure.
New in version 2.16.
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error
(self) → QgsError¶ Gets current status error. This error describes some principal problem for which provider cannot work and thus is not valid. It is not last error after accessing data by block(), identify() etc.
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extent
(self) → QgsRectangle¶ Returns the extent of the layer
- Returns
QgsRectangle containing the extent of the layer
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fileRasterFilters
(self) → str¶ Returns raster file filter string
Returns a string suitable for a QFileDialog of raster file formats supported by the data provider. Naturally this will be an empty string for those data providers that do not deal with plain files, such as databases and servers.
Note
It’d be nice to eventually be raster/vector neutral.
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fileVectorFilters
(self) → str¶ Returns vector file filter string
Returns a string suitable for a QFileDialog of vector file formats supported by the data provider. Naturally this will be an empty string for those data providers that do not deal with plain files, such as databases and servers.
Note
It’d be nice to eventually be raster/vector neutral.
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fullExtentCalculated
¶ Emitted whenever a deferred extent calculation is completed by the provider.
Layers should connect to this signal and update their cached extents whenever it is emitted. [signal]
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invalidateConnections
(self, connection: str)¶ Invalidate connections corresponding to specified name
New in version 2.16.
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isSignalConnected
()¶
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isValid
(self) → bool¶ Returns true if this is a valid layer. It is up to individual providers to determine what constitutes a valid layer.
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layerMetadata
(self) → QgsLayerMetadata¶ Returns layer metadata collected from the provider’s source.
Individual data providers must implement this method if they support collecting metadata.
See also
New in version 3.0.
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leaveUpdateMode
(self) → bool¶ Leave update mode.
This is aimed at providers that can open differently the connection to the datasource, according it to be in update mode or in read-only mode. This method shall be balanced with a successful call to enterUpdateMode().
Most providers will have an empty implementation for that method.
Several successive calls to enterUpdateMode() can be done. So there is a concept of stack of calls that must be handled by the provider. Only the last call to leaveUpdateMode() will really turn update mode off.
- Returns
true in case of success (or no-op implementation), false in case of failure.
New in version 2.16.
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name
(self) → str¶ Returns a provider name
Essentially just returns the provider key. Should be used to build file dialogs so that providers can be shown with their supported types. Thus if more than one provider supports a given format, the user is able to select a specific provider to open that file.
note
Instead of being pure virtual, might be better to generalize this behavior and presume that none of the sub-classes are going to do anything strange with regards to their name or description?
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notify
¶ Emitted when the datasource issues a notification.
See also
New in version 3.0: [signal]
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providerProperty
(self, property: QgsDataProvider.ProviderProperty, defaultValue: Any = None) → Any¶ Gets the current value of a certain provider property. It depends on the provider which properties are supported.
New in version 2.16.
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receivers
()¶
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reloadData
(self)¶ Reloads the data from the source. Needs to be implemented by providers with data caches to synchronize with changes in the data source
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sender
()¶
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senderSignalIndex
()¶
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setDataSourceUri
(self, uri: str)¶ Set the data source specification. This may be a path or database connection string
- Parameters
uri – source specification
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setError
(self, error: QgsError)¶ Sets error message
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setLayerOrder
(self, layers: Iterable[str])¶ Reorder the list of layer names to be rendered by this provider (in order from bottom to top)
Note
layers must have been previously added.
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setListening
(self, isListening: bool)¶ Set whether the provider will listen to datasource notifications If set, the provider will issue notify signals.
The default implementation does nothing.
See also
New in version 3.0.
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setProviderProperty
(self, property: QgsDataProvider.ProviderProperty, value: Any)¶ Allows setting arbitrary properties on the provider. It depends on the provider which properties are supported.
New in version 2.16.
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setSubLayerVisibility
(self, name: str, vis: bool)¶ Set the visibility of the given sublayer name
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setSubsetString
(self, subset: str, updateFeatureCount: bool = True) → bool¶ Set the subset string used to create a subset of features in the layer. This may be a sql where clause or any other string that can be used by the data provider to create a subset. Must be implemented in the dataprovider.
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setUri
(self, uri: QgsDataSourceUri)¶ Set the data source specification.
New in version 3.0.
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subLayerCount
(self) → int¶ Returns the number of layers for the current data source
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subLayerStyles
(self) → List[str]¶ Sub-layer styles for each sub-layer handled by this provider, in order from bottom to top
Sub-layer styles are used to abstract the way the provider’s source can symbolise layers in some way at the server, before it serves them to the provider.
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subLayers
(self) → List[str]¶ Sub-layers handled by this provider, in order from bottom to top
Sub-layers are used when the provider’s source can combine layers it knows about in some way before it hands them off to the provider.
See also
SUBLAYER_SEPARATOR
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subsetString
(self) → str¶ Returns the subset definition string (typically sql) currently in use by the layer and used by the provider to limit the feature set. Must be overridden in the dataprovider, otherwise returns a null QString.
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supportsSubsetString
(self) → bool¶ Returns true if the provider supports setting of subset strings.
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timerEvent
()¶
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timestamp
(self) → QDateTime¶ Time stamp of data source in the moment when data/metadata were loaded by provider
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updateExtents
(self)¶ Update the extents of the layer. Not implemented by default.
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uri
(self) → QgsDataSourceUri¶ Gets the data source specification.
New in version 3.0.
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writeLayerMetadata
(self, metadata: QgsLayerMetadata) → bool¶ Writes layer
metadata
to the underlying provider source. Support depends on individual provider capabilities.Returns true if metadata was successfully written to the data provider.
See also
New in version 3.0.
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