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