Qt Creator, SQLite3, and JSON1 example?

BSL787

Hello. I hope I'm placing this post in the appropriate group.

I am using Qt Creator 4.10, with SQLite3 (v. 3.32), with no problem. Now, I recently added the JSON1 extension to the SQLite3 dll with:

`gcc -g -shared -DSQLITE_ENABLE_JSON1 json1.c sqlite3ext.h -o json1.dll

I started implementing the JSON1 extension in my Qt Creator project by adding this code to my Qt main.cpp file; it compiles still, and writes the standard SQL database file in

//-------------------------------------------------------------------------------------------------
#include <QCoreApplication>
#include <QtDebug>
#include <QtSql/QtSql>
#include <QString>

//-------------------------------------------------------------------------------------------------
//https://sqlite.org/loadext.html
/* Add your header comment here */
#include <C:/sqlite3/sqlite-amalgamation-3320200/sqlite3ext.h> /* Do not use <sqlite3.h>! */

SQLITE_EXTENSION_INIT1

/* Insert your extension code here */

#ifdef _WIN32
__declspec(dllexport)
#endif
/* TODO: Change the entry point name so that "extension" is replaced by  text derived from the shared library filename as follows:  Copy every  ASCII alphabetic character from the filename after the last "/" through the next following ".", converting each character to lowercase, and discarding the first three characters if they are "lib".
*/

int sqlite3_extension_init(
  sqlite3 *db,
  char **pzErrMsg,
  const sqlite3_api_routines *pApi
)

{
  int rc = SQLITE_OK;
  SQLITE_EXTENSION_INIT2(pApi);

  /* Insert here calls to  sqlite3_create_function_v2(), sqlite3_create_collation_v2(), sqlite3_create_module_v2(), and/or sqlite3_vfs_register() to register the new features that your extension adds.
  */
  return rc;
}
//------------------------------------------------------------------------------------------------------
//my original Qt project code...with credits to various, useful YouTube tutorials (available listing)

const QString pathName = "C:\\Users\\firstName_lastName\\Qt_database_QtSql\\";
const QString databaseName = "new.db";
const QString pathAndFileName = pathName + databaseName;
const QString hostName = "bigBlue"; //"112.17.98.18"); // fake ip ;
const QString userName = "firstName_lastName";
const QString userPassword = "i_dunno";
const int portNumber = 3306;

void addValues( int ID, QString firstName, QString lastName, QString  birthDate, double weight  );

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    qDebug() << "start";
    //------------------------------------------------------------------------------------------------------------------
    //  set up database object and db file path and name
    QSqlDatabase db;
    db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName(pathAndFileName);
    db.setHostName(hostName);
    db.setPort(portNumber);
    db.setUserName(userName);
    db.setPassword(userPassword);
    //------------------------------------------------------------------------------------------------------------------
    //  open db with if() statement to catch errors
    if(!db.open())
    {
        qDebug()<<"problem opening database";
    }
    //------------------------------------------------------------------------------------------------------------------
    //  create the db table with fields and field types
    QString query = "CREATE TABLE testTable ("
            "ID integer PRIMARY KEY NOT NULL,"
            "firstName VARCHAR(20),"
            "lastName VARCHAR(20),"
            "birthDate DATETIME,"
            "weight double);";

    QSqlQuery qry;

    if(!qry.exec(query))
    {
        qDebug()<<"error creating table";
    }
    //------------------------------------------------------------------------------------------------------------------
    // adding values to table

    addValues(1, "John", "Parker", "01-01-1984", 156.5);
    addValues(2, "John", "Emdall", "02-02-1995", 181.3);
    addValues(3, "John", "Whorfin", "01-01-1995", 181.5);
    addValues(4, "John", "O'Connor", "01-01-1995", 181.5);

    db.close();

    qDebug() << "stop";
    return a.exec();
}
//------------------------------------------
void addValues( int ID, QString firstName, QString lastName, QString  birthDate, double weight  )
{
    QSqlQuery qry;
    qry.prepare("INSERT into testTable ("
                "ID,"
                "firstName,"
                "lastName,"
                "birthDate,"
                "weight) "
                "VALUES (?, ?, ?, ?, ?);");

    qry.addBindValue(ID);
    qry.addBindValue(firstName);
    qry.addBindValue(lastName);
    qry.addBindValue(QDateTime::fromString( birthDate, "mm-dd-yyyy"));
    qry.addBindValue(weight);

    if(!qry.exec())
    {
        qDebug()<<"error adding values to table";
    }
}

The SQLITE_EXTENSION_INIT1 statement appears to be a problem:

SQLITE_EXTENSION_INIT1

gives:

main.cpp:10:1: warning: zero as null pointer constant
sqlite3ext.h:647:77: note: expanded from macro 'SQLITE_EXTENSION_INIT1'

Am I on the right track?

Are there any assets or examples for the use of JSON1 in Qt Creator? I have found none on-line yet.

I have found lots of information on-line on using the JSON1 extension in SQLite3 at its command-line level, and all the documentation on the JSON1 extension functions and features.

Christian Ehrlicher

Don't know what you really want to achieve by including the sqlite3 sources but Qt will not use it - it will use the QSqlite3 plugin provided by your Qt installation. And there json support is enabled since Qt 5.13