好了,现在我在MDI应用程序中找到了整个持久qsql数据库,我尝试在QThread中访问它:
class LoadWorker(QThread):
totalSignal = pyqtSignal(int)
countSignal = pyqtSignal(int)
def __init__(self, parent=None):
super(LoadWorker, self).__init__(parent)
self.threadActive = True
self.commitsize = 200
self.filename = ""
def run(self):
query = QSqlQuery()
query.exec("DELETE FROM mytable")
#rest of code here
运行时,我收到一个错误:
^{pr2}$一些研究表明,我应该为线程启动一个新的DB连接,因此我做了以下更改:
class LoadWorker(QThread):
totalSignal = pyqtSignal(int)
countSignal = pyqtSignal(int)
def __init__(self, parent=None):
super(LoadWorker, self).__init__(parent)
self.threadActive = True
self.commitsize = 200
self.filename = ""
self.database = QSqlDatabase.addDatabase('QSQLITE',"loader")
if self.database:
self.database.setDatabaseName("database/clireports.db")
else:
QMessageBox.critical(None, "Database Error", "Unable To Connect To The Database!")
self.stop()
def run(self):
query = QSqlQuery()
query.exec("DELETE FROM mytable")
#rest of code here
然而,我仍然得到同样的错误。有什么不一样的事我需要做吗?在
修改代码:
class LoadWorker(QThread):
totalSignal = pyqtSignal(int)
countSignal = pyqtSignal(int)
def __init__(self, parent=None):
super(LoadWorker, self).__init__(parent)
self.threadActive = True
self.commitsize = 200
self.filename = ""
def run(self):
database = QSqlDatabase.addDatabase("QSQLITE","loader")
database.setDatabaseName("database/clireports.db") # <---
if not database.open():
print("Database Error","Unable to connect to the database!")
self.stop()
# database.setDatabaseName("database/clireports.db")
query = QSqlQuery()
query.exec("DELETE FROM mytable")
未修订代码:
class LoadWorker(QThread):
totalSignal = pyqtSignal(int)
countSignal = pyqtSignal(int)
def __init__(self, parent=None):
super(LoadWorker, self).__init__(parent)
self.threadActive = True
self.commitsize = 200
self.filename = ""
def run(self):
database = QSqlDatabase.addDatabase("QSQLITE","loader")
database.setDatabaseName("database/clireports.db")
if not database.open():
print("Database Error","Unable to connect to the database!")
self.stop()
query = QSqlQuery()
query.exec("DELETE FROM cptdata")
with open(self.filename, 'r', encoding="ISO-8859-1") as f:
reader = csv.reader(f,delimiter='\t')
data = list(reader)
self.totalSignal.emit(len(data))
f.close()
counter = 0
query.exec_("BEGIN TRANSACTION")
for row in data:
if self.threadActive == False: break
counter +=1
self.countSignal.emit(counter)
if len(row) < 3: continue
if "/" in row[0] or "Code" in row[0]: continue
recordid = str(uuid.uuid1())
cptcode = row[0].strip().upper()
formatcode = cptcode[:5]
description = row[2].strip().upper()
if cptcode == "": continue
query.prepare("INSERT INTO cptdata (recordid,cptcode,description) VALUES(:recordid,:cptcode,:description)")
query.bindValue(":recordid", str(recordid))
query.bindValue(":cptcode", str(formatcode))
query.bindValue(":description", str(description))
if query.exec_():
if counter % 200==0:
database.commit()
query.exec_("BEGIN TRANSACTION")
database.commit()
def stop(self):
self.threadActive = False
self.wait()
class CptLoader(QDialog):
def __init__(self, parent=None):
super(CptLoader, self).__init__(parent)
loadUi("GlobalUI/fileloader.ui", self)
def beginLoad(self,filename):
self.thread = LoadWorker(self)
self.thread.filename = filename
self.thread.totalSignal.connect(self.prgLoader.setMaximum)
self.thread.countSignal.connect(self.prgLoader.setValue)
self.thread.start()
你必须相信QSqlDatabase在你想要工作的线程中,你不能把它移到另一个线程,所以你必须为你想要数据库使用的每个线程创建一个新的连接。在
另一方面,
QThread
不是一个线程,而是它创建的线程的处理程序,因此构造函数方法属于创建QThread
对象的线程,它不同于在run()
方法中执行的处理QThread
的线程,总之,如果你想在这个方法中使用它。在另一方面,您不能从另一个线程创建GUI,在您的例子中,我看到您希望显示一条来自另一个线程的
QMessageBox
的消息,这在Qt中是禁止的。在示例:
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