How to fill default parameters in yaml file using python

Question

I have a YAML file with content:

       image_name: ubuntu
       components:
                 image_name: ubuntu
                 image_flavors: [medium, large]
                 image_ip : 192.168.12.134
                 imageuser : ubuntu
                 image_pass : ubuntu
                 image_config: /home/ubuntu/
                 image_net_type: vlan 
                 image_switch_type: ovs

I have implemented a script for this to load YAML file and o/p I have got in dict format.

       with open("test.yaml", "r") as input:
        try:
            a = yaml.safe_load(input)
            print "Parsing YAML file is completed"
            print a
        except yaml.YAMLError as error:
            print(error)

my dict format as below:

{'image_name': 'ubuntu', 'components': {'image_ip': '192.168.12.134', 
 'image_pass': 'ubuntu', 'image_switch_type': 'ovs', 'imageuser': 'ubuntu',
 'image_name': 'ubuntu', 'image_flavors': ['medium', 'large'], 
 'image_net_type': 'vlan', 'image_config': '/home/ubuntu/'}}

How I can fill default parameters if any key has no values?

Answer 1

One option is when you are getting a value for a key in the dict that was parsed from the yaml, use the get() method of the dict. so

value = a.get('key', 'default')

If the key key is in a it will return the value else it will return whatever you specify as the default. In the above e.g that would be 'default'