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/** \ingroup core
* \class QgsJSONExporter
* \brief Handles exporting QgsFeature features to GeoJSON features.
*
* Note that geometries will be automatically reprojected to WGS84 to match GeoJSON spec
* if either the source vector layer or source CRS is set.
* \note Added in version 2.16
*/
class QgsJSONExporter
{
%TypeHeaderCode
#include <qgsjsonutils.h>
%End
public:
/** Constructor for QgsJSONExporter.
* @param vectorLayer associated vector layer (required for related attribute export)
* @param precision maximum number of decimal places to use for geometry coordinates
*/
QgsJSONExporter( const QgsVectorLayer* vectorLayer = nullptr, int precision = 17 );
/** Sets the maximum number of decimal places to use in geometry coordinates.
* @param precision number of decimal places
* @see precision()
*/
void setPrecision( int precision );
/** Returns the maximum number of decimal places to use in geometry coordinates.
* @see setPrecision()
*/
int precision() const;
/** Sets whether to include geometry in the JSON exports.
* @param includeGeometry set to false to prevent geometry inclusion
* @see includeGeometry()
*/
void setIncludeGeometry( bool includeGeometry );
/** Returns whether geometry will be included in the JSON exports.
* @see setIncludeGeometry()
*/
bool includeGeometry() const;
/** Sets whether to include attributes in the JSON exports.
* @param includeAttributes set to false to prevent attribute inclusion
* @see includeAttributes()
*/
void setIncludeAttributes( bool includeAttributes );
/** Returns whether attributes will be included in the JSON exports.
* @see setIncludeAttributes()
*/
bool includeAttributes() const;
/** Sets whether to include attributes of features linked via references in the JSON exports.
* @param includeRelated set to true to include attributes for any related child features
* within the exported properties element.
* @note associated vector layer must be set with setVectorLayer()
* @see includeRelated()
*/
void setIncludeRelated( bool includeRelated );
/** Returns whether attributes of related (child) features will be included in the JSON exports.
* @see setIncludeRelated()
*/
bool includeRelated() const;
/** Sets the associated vector layer (required for related attribute export). This will automatically
* update the sourceCrs() to match.
* @param vectorLayer vector layer
* @see vectorLayer()
*/
void setVectorLayer( const QgsVectorLayer* vectorLayer );
/** Returns the associated vector layer, if set.
* @see setVectorLayer()
*/
QgsVectorLayer* vectorLayer() const;
/** Sets the source CRS for feature geometries. The source CRS must be set if geometries are to be
* correctly automatically reprojected to WGS 84, to match GeoJSON specifications.
* @param crs source CRS for input feature geometries
* @note the source CRS will be overwritten when a vector layer is specified via setVectorLayer()
* @see sourceCrs()
*/
void setSourceCrs( const QgsCoordinateReferenceSystem& crs );
/** Returns the source CRS for feature geometries. The source CRS must be set if geometries are to be
* correctly automatically reprojected to WGS 84, to match GeoJSON specifications.
* @see setSourceCrs()
*/
const QgsCoordinateReferenceSystem& sourceCrs() const;
/** Sets the list of attributes to include in the JSON exports.
* @param attributes list of attribute indexes, or an empty list to include all
* attributes
* @see attributes()
* @see setExcludedAttributes()
* @note Attributes excluded via setExcludedAttributes() take precedence over
* attributes specified by this method.
*/
void setAttributes( const QgsAttributeList& attributes );
/** Returns the list of attributes which will be included in the JSON exports, or
* an empty list if all attributes will be included.
* @see setAttributes()
* @see excludedAttributes()
* @note Attributes excluded via excludedAttributes() take precedence over
* attributes returned by this method.
*/
QgsAttributeList attributes() const;
/** Sets a list of attributes to specifically exclude from the JSON exports. Excluded attributes
* take precedence over attributes included via setAttributes().
* @param attributes list of attribute indexes to exclude
* @see excludedAttributes()
* @see setAttributes()
*/
void setExcludedAttributes( const QgsAttributeList& attributes );
/** Returns a list of attributes which will be specifically excluded from the JSON exports. Excluded attributes
* take precedence over attributes included via attributes().
* @see setExcludedAttributes()
* @see attributes()
*/
QgsAttributeList excludedAttributes() const;
/** Returns a GeoJSON string representation of a feature.
* @param feature feature to convert
* @param extraProperties map of extra attributes to include in feature's properties
* @param id optional ID to use as GeoJSON feature's ID instead of input feature's ID. If omitted, feature's
* ID is used.
* @returns GeoJSON string
* @see exportFeatures()
*/
QString exportFeature( const QgsFeature& feature,
const QVariantMap& extraProperties = QVariantMap(),
const QVariant& id = QVariant() ) const;
/** Returns a GeoJSON string representation of a list of features (feature collection).
* @param features features to convert
* @returns GeoJSON string
* @see exportFeature()
*/
QString exportFeatures( const QgsFeatureList& features ) const;
private:
QgsJSONExporter( const QgsJSONExporter& );
};
/** \ingroup core
* \class QgsJSONUtils
* \brief Helper utilities for working with JSON and GeoJSON conversions.
* \note Added in version 2.16
*/
class QgsJSONUtils
{
%TypeHeaderCode
#include <qgsjsonutils.h>
%End
public:
/** Attempts to parse a GeoJSON string to a collection of features.
* @param string GeoJSON string to parse
* @param fields fields collection to use for parsed features
* @param encoding text encoding
* @returns list of parsed features, or an empty list if no features could be parsed
* @see stringToFields()
* @note this function is a wrapper around QgsOgrUtils::stringToFeatureList()
*/
static QgsFeatureList stringToFeatureList( const QString& string, const QgsFields& fields, QTextCodec* encoding );
/** Attempts to retrieve the fields from a GeoJSON string representing a collection of features.
* @param string GeoJSON string to parse
* @param encoding text encoding
* @returns retrieved fields collection, or an empty list if no fields could be determined from the string
* @see stringToFeatureList()
* @note this function is a wrapper around QgsOgrUtils::stringToFields()
*/
static QgsFields stringToFields( const QString& string, QTextCodec* encoding );
/** Encodes a value to a JSON string representation, adding appropriate quotations and escaping
* where required.
* @param value value to encode
* @returns encoded value
*/
static QString encodeValue( const QVariant& value );
/** Exports all attributes from a QgsFeature as a JSON map type.
* @param feature feature to export
*/
static QString exportAttributes( const QgsFeature& feature );
};
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