QGIS API Documentation  3.27.0-Master (0e23467727)
qgsqueryresultmodel.h
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1 /***************************************************************************
2  qgsqueryresultmodel.h - QgsQueryResultModel
3 
4  ---------------------
5  begin : 24.12.2020
6  copyright : (C) 2020 by Alessandro Pasotti
7  email : [email protected]
8  ***************************************************************************
9  * *
10  * This program is free software; you can redistribute it and/or modify *
11  * it under the terms of the GNU General Public License as published by *
12  * the Free Software Foundation; either version 2 of the License, or *
13  * (at your option) any later version. *
14  * *
15  ***************************************************************************/
16 #ifndef QgsQueryResultModel_H
17 #define QgsQueryResultModel_H
18 
19 #include <QAbstractTableModel>
20 #include <QThread>
21 
22 #include "qgis_core.h"
23 #include "qgis_sip.h"
24 
26 
28 
29 #ifndef SIP_RUN
30 
35 class QgsQueryResultFetcher: public QObject
36 {
37  Q_OBJECT
38 
39  public:
40 
42  QgsQueryResultFetcher( const QgsAbstractDatabaseProviderConnection::QueryResult *queryResult )
43  : mQueryResult( queryResult )
44  {}
45 
47  void fetchRows( long long maxRows = -1 );
48 
50  void stopFetching();
51 
52  signals:
53 
55  void rowsReady( const QList<QList<QVariant>> &newRows );
56 
58  void fetchingComplete();
59 
60  private:
61 
62  const QgsAbstractDatabaseProviderConnection::QueryResult *mQueryResult = nullptr;
63  QAtomicInt mStopFetching = 0;
64  // Number of rows rows to fetch before emitting rowsReady
65  static const int ROWS_BATCH_COUNT;
66 
67 };
68 
69 #endif
70 
72 
73 
80 class CORE_EXPORT QgsQueryResultModel : public QAbstractTableModel
81 {
82  Q_OBJECT
83  public:
84 
88  QgsQueryResultModel( const QgsAbstractDatabaseProviderConnection::QueryResult &queryResult, QObject *parent = nullptr );
89 
91 
92  // QAbstractItemModel interface
93  public:
94 
95  int rowCount( const QModelIndex &parent ) const override;
96  int columnCount( const QModelIndex &parent ) const override;
97  QVariant data( const QModelIndex &index, int role ) const override;
98  QVariant headerData( int section, Qt::Orientation orientation, int role ) const override;
99 
100  void fetchMore( const QModelIndex &parent ) override;
101  bool canFetchMore( const QModelIndex &parent ) const override;
102 
104  QStringList columns() const;
105 
111 
112  public slots:
113 
117  void rowsReady( const QList<QList<QVariant> > &rows );
118 
122  void cancel();
123 
124 
125  signals:
126 
133 
138  void fetchMoreRows( qlonglong maxRows );
139 
144 
145  private:
146 
148  QStringList mColumns;
149  QThread mWorkerThread;
150  std::unique_ptr<QgsQueryResultFetcher> mWorker;
151  QList<QVariantList> mRows;
152 
154  static const int FETCH_MORE_ROWS_COUNT;
155 
156 };
157 
158 #endif // qgsqueryresultmodel.h
The QgsQueryResultModel class is a model for QgsAbstractDatabaseProviderConnection::QueryResult.
void fetchingStarted()
Emitted when fetching of rows has started.
void fetchMoreRows(qlonglong maxRows)
Emitted when more rows are requested.
void fetchingComplete()
Emitted when rows have been fetched (all of them or a batch if maxRows was passed to fetchMoreRows() ...
The QueryResult class represents the result of a query executed by execSql()