Passing values between forms with npyscreen - python-curses

Question

I am trying to create a simple npyscreen curses application in python that requests user input on one screen, and then verifies it for the user on another screen.
Mostly, this is an effort to understand how values are stored and retrieved from within npyscreen. I am sure I am missing something simple, but I have been unable to find (or understand?) the answer within the documentation.
Sample code below which will not pass the value properly:
#!/usr/bin/env python3.5
import npyscreen as np
class EmployeeForm(np.Form):
def afterEditing(self):
self.parentApp.switchForm('CONFIRMFM')
def create(self):
self.myName = self.add(np.TitleText, name='Name')
self.myDepartment = self.add(np.TitleSelectOne, scroll_exit=True, max_height=3, name='Department', values = ['Department 1', 'Department 2', 'Department 3'])
self.myDate = self.add(np.TitleDateCombo, name='Date Employed')
class EmployeeConfirmForm(np.Form):
def afterEditing(self):
self.parentApp.setNextForm(None)
def create(self):
self.value = None
self.wgName = self.add(np.TitleText, name = "Name:",)
self.wgDept = self.add(np.TitleText, name = "Dept:")
self.wgEmp = self.add(np.TitleText, name = "Employed:")
def beforeEditing(self):
if self.value:
self.name = "Is this correct?"
self.wgName.value = self.myName.value
self.wgDept.value = self.myDepartment.value
self.wgEmp.value = self.myDate.value
def on_cancel(self):
self.parentApp.switchFormPrevious()
class myApp(np.NPSAppManaged):
def onStart(self):
self.addForm('MAIN', EmployeeForm, name='Employee Entry')
self.addForm('CONFIRMFM', EmployeeConfirmForm, name='Employee Confirmation')
if __name__ == '__main__':
TestApp = myApp().run()

Answer 1

I haven't found a straightforward way to directly pass variables between forms. However, you can work around this by using variables that have a global scope among forms.
The NPSAppManaged app class runs completely encapsulated, so if you try to declare global variables at the top of the Python file, the forms within will not have access to them. Instead, declare the variables inside the NPSAppManaged app class before the onStart method as shown below.
class myApp(np.NPSAppManaged):
# declare variables here that have global scope to all your forms
myName, myDepartment, myDate = None, None, None
def onStart(self):
self.addForm('MAIN', EmployeeForm, name='Employee Entry')
self.addForm('CONFIRMFM', EmployeeConfirmForm, name='Employee Confirmation')
if __name__ == '__main__':
TestApp = myApp().run()
You can then access these variables using self.parentApp.[variable name] as follows:
class EmployeeConfirmForm(np.Form):
def afterEditing(self):
self.parentApp.setNextForm(None)
def create(self):
self.add(np.FixedText, value = "Is this correct?")
self.wgName = self.add(np.TitleText, name = "Name:", value = self.parentApp.myName)
self.wgDept = self.add(np.TitleText, name = "Dept:", value = self.parentApp.myDepartment)
self.wgEmp = self.add(np.TitleText, name = "Employed:", value = self.parentApp.myDate)
def on_cancel(self):
self.parentApp.switchFormPrevious()
Note: you don't need to have a separate beforeEditing method since the values will be loaded directly into EmployeeConfirmForm during the create method from the app class global variables.

Answer 2

One way to do this is to use getForm before switchForm to pass the values. The following works for me using python2 to pass the name. Passing other values should be similar. I'm very much learning this myself but please comment if you have further questions.
import npyscreen as np
class EmployeeForm(np.ActionForm):
def create(self):
self.myName = self.add(np.TitleText, name='Name')
self.myDepartment = self.add(np.TitleSelectOne, scroll_exit=True, max_height=3, name='Department', values = ['Department 1', 'Department 2', 'Department 3'])
self.myDate = self.add(np.TitleDateCombo, name='Date Employed')
def afterEditing(self):
self.parentApp.getForm('CONFIRMFM').wgName.value = self.myName.value
self.parentApp.switchForm('CONFIRMFM')
class EmployeeConfirmForm(np.Form):
def afterEditing(self):
self.parentApp.setNextForm(None)
def create(self):
self.value = None
self.wgName = self.add(np.TitleFixedText, name = "Name:",)
self.wgDept = self.add(np.TitleText, name = "Dept:")
self.wgEmp = self.add(np.TitleText, name = "Employed:")
def on_cancel(self):
self.parentApp.switchFormPrevious()
class myApp(np.NPSAppManaged):
def onStart(self):
self.addForm('MAIN', EmployeeForm, name='Employee Entry')
self.addForm('CONFIRMFM', EmployeeConfirmForm, name='Employee Confirmation')
if __name__ == '__main__':
TestApp = myApp().run()

Answer 3

Assign values (including the value returned by addForm) to self.whatever.
So if you do
self.myAppValue = 2
self.mainForm = self.addForm('MAIN', MainForm, ...)
self.form2 = self.addForm('FORM2', Form2, ...)
you can use these in any form
self.parentApp.myAppValue
self.parentApp.mainForm.main_form_widget.main_form_value
And in myApp() you can do
self.mainForm.main_form_widget.main_form_value

Answer 4

I had the same problems during development as the documentation is not very detailed about passing values between forms.
I have added a few modification, the first one was changing Form to ActionForm in the confirmation form to have access to ok and cancel buttons. Secondly, the values on the confirmation form should not be editable as this is a confirmation. You can press cancel to edit on the previous form. The last one was passing the first element of the department list rather than the value - it would be just a list index. I hope it helps a little.
#!/usr/bin/env python3.5
import npyscreen as np
class EmployeeForm(np.Form):
def create(self):
self.myName = self.add(np.TitleText, name='Name')
self.myDepartment = self.add(np.TitleSelectOne, scroll_exit=True, max_height=3, name='Department', values = ['Department 1', 'Department 2', 'Department 3'])
self.myDate = self.add(np.TitleDateCombo, name='Date Employed')
def afterEditing(self):
self.parentApp.switchForm('CONFIRMFM')
self.parentApp.getForm('CONFIRMFM').wgName.value = self.myName.value
self.parentApp.getForm('CONFIRMFM').wgDept.value = self.myDepartment.values[0]
self.parentApp.getForm('CONFIRMFM').wgEmp.value = self.myDate.value
class EmployeeConfirmForm(np.ActionForm):
def create(self):
self.add(np.FixedText, value="Is this correct?", editable=False)
self.wgName = self.add(np.TitleText, name = "Name:", editable=False)
self.wgDept = self.add(np.TitleText, name = "Dept:", editable=False)
self.wgEmp = self.add(np.TitleText, name = "Employed:", editable=False)
def on_ok(self):
self.parentApp.setNextForm(None)
def on_cancel(self):
self.parentApp.switchFormPrevious()
class myApp(np.NPSAppManaged):
def onStart(self):
self.addForm('MAIN', EmployeeForm, name='Employee Entry')
self.addForm('CONFIRMFM', EmployeeConfirmForm, name='Employee Confirmation')
if __name__ == '__main__':
TestApp = myApp().run()