qt-sqlite-orm.h

#pragma once

#include <QString>

#include "sqlite_orm.h"

namespace sqlite_orm {

/**
 *  First of all is a type_printer template class.
 *  It is responsible for sqlite type string representation.
 *  We want Gender to be `TEXT` so let's just derive from
 *  text_printer. Also there are other printers: real_printer and
 *  integer_printer. We must use them if we want to map our type to
 * `REAL` (double/float)
 *  or `INTEGER` (int/long/short etc) respectively.
 */
template <>
struct type_printer<QString> : public text_printer {};

/**
 *  This is a binder class. It is used to bind c++ values to sqlite
 * queries.
 *  Here we have to create gender string representation and bind it as
 * string.
 *  Any statement_binder specialization must have `int
 * bind(sqlite3_stmt*, int, const T&)` function
 *  which returns bind result. Also you can call any of `sqlite3_bind_*`
 * functions directly.
 *  More here https://www.sqlite.org/c3ref/bind_blob.html
 */
template <>
struct statement_binder<QString> {
  int bind(sqlite3_stmt* stmt, int index, const QString& value) {
    return statement_binder<std::string>().bind(stmt, index,
                                                value.toStdString());
    //  or return sqlite3_bind_text(stmt, index++,
    //  GenderToString(value).c_str(), -1, SQLITE_TRANSIENT);
  }
};

/**
 *  field_printer is used in `dump` and `where` functions. Here we have
 * to create
 *  a string from mapped object.
 */
template <>
struct field_printer<QString> {
  std::string operator()(const QString& t) const { return t.toStdString(); }
};

/**
 *  This is a reverse operation: here we have to specify a way to
 * transform string received from
 *  database to our Gender object. Here we call `GenderFromString` and
 * throw `std::runtime_error` if it returns
 *  nullptr. Every `row_extractor` specialization must have
 * `extract(const char*)` and `extract(sqlite3_stmt *stmt, int columnIndex)`
 *  functions which return a mapped type value.
 */
template <>
struct row_extractor<QString> {
  QString extract(const char* row_value) {
    return QString::fromStdString(row_value);
  }

  QString extract(sqlite3_stmt* stmt, int columnIndex) {
    auto str = sqlite3_column_text(stmt, columnIndex);
    return this->extract((const char*)str);
  }
};
}  // namespace sqlite_orm