我有一个带有两个表的SQLite数据库:
vertex(ID int primary key, name varchar(64));
edge(ID int primary key, sourceID int references vertex(ID), targetID int references vertex(ID));
在我的桌面应用程序中,我正在使用模型/视图的自定义类
MyTableView : public QTableView
VertexTableModel : public QSqlTableModel
EdgeTableModel : public QSqlRelationalTableModel
我正在这样设置它们:
GraphyEditor::GraphyEditor(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::GraphyEditor),
vertexModel(new VertexTableModel(parent)),
edgeModel(new EdgeTableModel(parent)) {
ui->setupUi(this);
vertexModel->setTable("vertex");
ui->vertices->setModel(vertexModel); // ui->vertices is *MyTableView
edgeModel->setTable("edge");
//TODO find fix to the issue
// edgeModel->setRelation(1, QSqlRelation("vertex", "ID", "name"));
// edgeModel->setRelation(2, QSqlRelation("vertex", "ID", "name"));
ui->edges->setModel(edgeModel); // ui->egdes is *MyTableView
}
此代码可以正常工作并正确显示数据,但我想将sourceID
中的第1列和第2列(targetID
和edgeModel
)从vertex.ID
替换为vertex.name
我进行了一些搜索,找到了setRelation
方法(我在代码中注释了同样的方法,但是当我使用它时,edgeModel
表未显示任何边缘。
是因为我的表模式,还是我的代码有问题?
我该如何实现?
编辑:
因为似乎问题出在代码中的其他地方,所以这里是带有完整代码的仓库:https://github.com/jaro2gw/Graphy
您的问题可能隐藏在项目中您未提供的其他地方,但没有隐藏在使用QSqlRelationalTableModel的代码中。
您的(注释)代码中只有一个最小的问题:两个替换的列将具有相同的名称:“名称”,但是您可以在定义QSqlRelation
时重命名两个列。
这里是先生。以说明如何处理您的两个表和一个QSqlRelationalTableModel,以防万一其他人来stackoverflow询问类似的问题。
SQLite数据库转储:
PRAGMA foreign_keys=OFF;
BEGIN TRANSACTION;
CREATE TABLE `vertex` (
`ID` INTEGER,
`name` TEXT,
PRIMARY KEY(`ID`)
);
INSERT INTO vertex VALUES(1,'one');
INSERT INTO vertex VALUES(2,'two');
INSERT INTO vertex VALUES(3,'three');
INSERT INTO vertex VALUES(4,'four');
INSERT INTO vertex VALUES(5,'five');
INSERT INTO vertex VALUES(6,'six');
INSERT INTO vertex VALUES(7,'seven');
INSERT INTO vertex VALUES(8,'eight');
INSERT INTO vertex VALUES(9,'nine');
CREATE TABLE IF NOT EXISTS "edge" (
"ID" INTEGER,
"sourceID" INTEGER,
"targetID" INTEGER,
FOREIGN KEY("targetID") REFERENCES "vertex"("ID"),
PRIMARY KEY("ID"),
FOREIGN KEY("sourceID") REFERENCES "vertex"("ID")
);
INSERT INTO edge VALUES(1,1,4);
INSERT INTO edge VALUES(2,2,5);
INSERT INTO edge VALUES(3,3,6);
INSERT INTO edge VALUES(4,4,7);
INSERT INTO edge VALUES(5,5,8);
INSERT INTO edge VALUES(6,6,9);
COMMIT;
test.pro
QT = core sql
CONFIG += c++11 console
SOURCES += main.cpp
main.cpp
#include <QCoreApplication>
#include <QTextStream>
#include <QSqlDatabase>
#include <QSqlError>
#include <QSqlRelationalTableModel>
#include <QSqlRecord>
#include <QSqlField>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QTextStream cout(stdout, QIODevice::WriteOnly);
QTextStream cerr(stderr, QIODevice::WriteOnly);
auto db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName("test.db");
if (!db.open()) {
cerr << db.lastError().text() << endl;
return 1;
}
QSqlRelationalTableModel model;
model.setTable("edge");
model.setRelation(1, QSqlRelation("vertex", "ID", "name as sourceName"));
model.setRelation(2, QSqlRelation("vertex", "ID", "name as targetName"));
model.select();
auto rec = model.record();
// headers output
cout << qSetFieldWidth(15);
for(int i=0; i<rec.count(); ++i) {
cout << rec.field(i).name();
}
cout << endl;
// rows output
for(int i=0; i<model.rowCount(); ++i) {
rec = model.record(i);
cout << rec.value("ID").toInt() << rec.value("sourceName").toString() << rec.value("targetName").toString() << endl;
}
}
这是程序的输出:
ID sourceName targetName
1 one four
2 two five
3 three six
4 four seven
5 five eight
6 six nine