stop flask duplicating a loaded variable

Question

I\'m building a basic cloud infrastructure management site and have a problem with the page that lists virtual machines.

The flask app pulls a list that is generate

Answer 1

You need to initialise vm_list with an empty dict. And if a key exists, then append to its list, else set the dict[key] with an empty list. This is done by setdefault.

Try this:

def zip_list():
    ...
    vm_list = {}
    for node in driver.list_nodes():
        vm_list.setdefault('vmid', []).append(node.uuid)
        vm_list.setdefault('name', []).append(node.name)
        vm_list.setdefault('state', []).append(node.state)
        vm_list.setdefault('platform', []).append(node.platform)
    ...
        myVms = zip(vm_list['name'], vm_list['vmid'], vm_list['platform'], vm_list['state'])
        return myVms

Answer 2

You are close - the variable you actually need to reset each time is not myVms but vm_list, as follows:

class Node:
    counter = 0

    def __init__(self):
        c_str = str(Node.counter)
        self.uuid = "asdf" + c_str
        self.name = "test " + c_str
        self.state = "wow " + c_str + " such state"
        Node.counter += 1


class Driver:
    def __init__(self, number_of_nodes):
        self.nodes = []
        for x in range(number_of_nodes):
            self.nodes.append(Node())
        self.name = "the greatest driver"

    def list_nodes(self) -> list:
        return self.nodes


driver = Driver(10)


def zip_list():
    vm_list = {'vmid': [], 'name': [], 'state': [], 'platform': []}
    for node in driver.list_nodes():
        vm_list["vmid"].append(node.uuid)
        vm_list["name"].append(node.name)
        vm_list["state"].append(node.state)
        vm_list["platform"].append(driver.name)

    myVms = zip(vm_list['name'], vm_list['vmid'], vm_list['platform'], vm_list['state'])
    return myVms


print("First time:")

my_list = zip_list()
for i in my_list:
    print(i)

print("Second time:")

my_list = zip_list()
for i in my_list:
    print(i)

If you initialise vm_list outside of the zip_list() function instead, you will see the doubling up that you are experiencing.