Python, delete JSON element having specific key from a loop

Question

Using Python, I need to delete all objects in JSON array that have specific value of 'name' key. However, I can't do that from a loop.

Imaging I want to delete all items having 'bad' as name in the following input:

{
  'myArray' : [
    {
      'name' : 'good',
      'value' : '1'
    },
    {
      'name' : 'bad',
      'value' : '2'
    }
  ]
}

So I use the following Python test case:

myData = {'myArray': [{'name': 'good', 'value': '1'}, {'name': 'bad', 'value': '2'}]}

for a in myData['myArray']:
  if (a['name'] =='bad'):
    del a

print(json.dumps(myData))

And I see that the myData is not changed.

I assume this is because I try to delete an iterator of a loop, that might be considered as risky action by interpreter, however no runtime error or warning is reported by Python.

What's the recommended approach in this case?

Thanks!

Answer 1

One of approaches from Remove element from list when using enumerate() in python - a loop over a copy of the list referred as [:] - works too:

for a in myData['myArray'][:]:
  if (a['name'] == u'bad'):
     myData['myArray'].remove(a)

Thanks everyone!

Answer 2

Use a (nested) dict/list comprehension. Never try to delete elements of an object while iterating over it

>>> [x for x in myData['myArray'] if x['name'] != 'bad']
[{'name': 'good', 'value': '1'}]

Assign the result to myData['myArray'], or whatever you want.