PyQt - SQLAlchemy 不接受 QString [英] PyQt - SQLAlchemy doesn't accept QString

问题描述

我正在使用 PyQt 和 SQLAlchemy，而 SQLAlchemy 不接受 QStrings.有没有办法将 QStrings 传递给它，或者我每次都必须将 QStrings 转换为 Python 字符串?

I'm using PyQt and SQLAlchemy and SQLAlchemy doesn't accept QStrings. Is there any way to pass QStrings to it or I have to convert QStrings to Python strings every single time?

谢谢.

代码如下:

import sip
sip.setapi('QString', 2)

from sqlalchemy import create_engine
from sqlalchemy import Table, Column, Integer, String, Float, MetaData, ForeignKey
from sqlalchemy.sql import select, and_
from PyQt4 import QtGui, QtCore

class DbUtils(object):
    def __init__(self, db_file = None, parent = None):

        self.db = None
        self.db_connection = None
        self.db_file = str(db_file)

    def db_open(self):
        self.db = create_engine('sqlite:///' + self.db_file)
        self.db_connection = self.db.connect()

    def db_close(self):
        self.db_connection.close()

    def db_create_voltdrop(self):
        metadata = MetaData()

        tb_cable_brands = Table('cable_brands', metadata,
            Column('id', Integer, primary_key=True),
            Column('brand', String)
            )
        tb_cable_types = Table('cable_types', metadata,
            Column('id', Integer, primary_key=True),
            Column('brand_id', None, ForeignKey('cable_brands.id')),
            Column('type', String),
            Column('alpha', String)
            )
        tb_cable_data = Table('cable_data', metadata,
            Column('id', Integer, primary_key=True),
            Column('type_id', None, ForeignKey('cable_types.id')),
            Column('size', String),
            Column('resistance', Float)
            )
        metadata.create_all(self.db)

    def delete_cable_brand(self, cable_brand):
        cable_brand = str(cable_brand)
        metadata = MetaData()
        metadata.bind = self.db

        tb_cable_brands = Table('cable_brands', metadata, autoload = True)

        cable_brands = select([tb_cable_brands.c.brand],
                          and_(tb_cable_brands.c.brand == cable_brand)
                          )
        row = self.db_connection.execute(cable_brands)
        data = row.fetchone()
        if str(data[0]) == cable_brand:
            cable_brands = tb_cable_brands.delete().where(tb_cable_brands.c.brand == cable_brand)
            self.db_connection.execute(cable_brands)
            return True
        else:
            return False

推荐答案

您可以 将 API 更改为 v2 并且 PyQt 将始终使用常规 Python 字符串而不是 QStrings.

You can change the API to v2 and PyQt will always use regular Python strings instead of QStrings.

编辑

案例 1:没有 sip.setapi

import sys
from PyQt4 import QtGui

app = QtGui.QApplication(sys.argv)
c = QtGui.QComboBox()
c.addItems(["one","two"])
print c.currentText(), type(c.currentText())
c.show()
sys.exit(app.exec_())

# Outputs
one <class 'PyQt4.QtCore.QString'>

案例 2:使用 sip.setapi

import sip
sip.setapi("QString",2)

import sys
from PyQt4 import QtGui

app = QtGui.QApplication(sys.argv)
c = QtGui.QComboBox()
c.addItems(["one","two"])
print c.currentText(), type(c.currentText())
c.show()
sys.exit(app.exec_())

# Outputs
one <type 'unicode'>

这篇关于PyQt - SQLAlchemy 不接受 QString的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！