[英]stop flask duplicating a loaded variable
I'm building a basic cloud infrastructure management site and have a problem with the page that lists virtual machines. 我正在构建一个基本的云基础架构管理站点,并且列出虚拟机的页面有问题。
The flask app pulls a list that is generated via various cloud platform's APIs, and is in the below format: flask应用程序提取通过各种云平台的API生成的列表,格式如下:
vm_list = {
'vmid': [],
'name': [],
'state': [],
'platform': []
}
the list is populated by looping through the API output and appending each value like so: 通过遍历API输出并附加每个值来填充列表,如下所示:
def zip_list():
...
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
I'm loading this via my flask app like this: 我正在通过我的烧瓶应用程序加载它,如下所示:
@app.route('/vms/')
def vms():
myVms = {}
myVms = vm.zip_list()
return render_template('VMs.html', vm_list=myVms)
The VMs.html
page loads this data into a table: VMs.html
页面将此数据加载到表中:
<table class="tableClass">
<tr>
<th>Name</th>
<th>id</th>
<th>Plaform</th>
<th>State</th>
</tr>
{% for row in vm_list %}
<tr>
<td>{{ row[0] }}</td>
<td>{{ row[1] }}</td>
<td>{{ row[2] }}</td>
<td>{{ row[3] }}</td>
<tr>
{% endfor %}
</table>
And this works fine, loading the data as expected. 并且可以正常工作,按预期加载数据。 However my problem is each time I refresh the page, the data is loaded and appended to the list once again, doubling the table size.
但是,我的问题是每次刷新页面时,数据都会再次加载并追加到列表中,从而使表大小增加了一倍。 Each refresh adds the whole
vm_list
list to the table once more. 每次刷新将整个
vm_list
列表再次添加到表中。
I had thought this may be resolved by "nulling" the myVms
variable each time it's called (ie myVms = {}
) in the flask app script and/or the zip_list
function but that doesn't seem to work; 我以为可以通过在flask应用程序脚本和/或
zip_list
函数中每次调用myVms
变量(即myVms = {}
)将myVms
变myVms
来解决此问题,但这似乎不起作用。 the issue still persists. 问题仍然存在。
I also looked into flask-caching to see if clearing flask's cache each reload would fix it but it appears not to. 我还查看了烧瓶缓存,以查看每次重新加载时清除烧瓶的缓存是否可以解决该问题,但似乎无法解决。
I'm thinking that I can change something in the html file to force this to only load once per session or something similar, but my front-end skills don't reach out that far. 我在想,我可以更改html文件中的某些内容,以强制每次会话仅加载一次或类似的内容,但是我的前端技能却作用不大。
Does anyone have any idea what I can do in this situation or where I'm going wrong? 有谁知道在这种情况下或在哪里出问题时我能做什么? Any advice is greatly appreciated.
任何意见是极大的赞赏。
You are close - the variable you actually need to reset each time is not myVms
but vm_list
, as follows: 您很接近-每次实际需要重置的变量不是
myVms
而是vm_list
,如下所示:
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. 如果您在
zip_list()
函数之外初始化vm_list
,则会看到正在经历的翻倍。
You need to initialise vm_list
with an empty dict
. 您需要使用空
dict
初始化vm_list
。 And if a key exists, then append to its list, else set the dict[key]
with an empty list. 如果存在密钥,则将其追加到列表中,否则将
dict[key]
设置为空列表。 This is done by setdefault
. 这是通过
setdefault
完成的。
Try this: 尝试这个:
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
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