Adding terms to Python dictionary

Question

I have the following valid dictionary. I'm trying to add another group of terms under the "expansion_modules" group.

lan_router = {
    'HOSTNAME1':{
        'system_type': 'MDF',
        'chassis':{
            0:{
                'model_num': 'EX4550',
                'vc_role': 'MASTER',
                'expansion_modules':{
                    1:{
                        'pic_slot': 1,
                        'expan_model': 'EX4550VCP'
                    }
                },
                'built-in_modules':{
                    0:{
                        'pic_slot': 2,
                        'built-in_model': 'EX4550BI'
                    }
                }
            }
        }
    }
}

I want to add the following under "expansion_modules" without removing "1"...

2:{'pic_slot': 2, 'expan_model': 'EX4550SFP'}

The following code adds what I want, but removes the existing term...

print lan_router['HOSTNAME1']['chassis'][0]['expansion_modules'][1]['expan_model']

lan_router['HOSTNAME1']['chassis'][0]['expansion_modules'] = { 2: {} }
lan_router['HOSTNAME1']['chassis'][0]['expansion_modules'][2] = {'pic_slot' : 1, 'expan_model' : 'EX45504XSFP'}

Answer 1

You do not need the line - lan_router['HOSTNAME1']['chassis'][0]['expansion_modules'] = { 2: {} } , it is replacing the dictionary inside expansion_modules , just remove this and execute rest.

Code -

print lan_router['HOSTNAME1']['chassis'][0]['expansion_modules'][1]['expan_model']

lan_router['HOSTNAME1']['chassis'][0]['expansion_modules'][2] = {'pic_slot' : 1, 'expan_model' : 'EX45504XSFP'}

Answer 2

Access it like this:

lan_router['HOSTNAME1']['chassis'][0]['expansion_modules'][2] = {}

Answer 3

Anand's answer is correct as it answers your question.

I would add that often dictionaries with [0, 1, ...] as keys should be just lists. Instead of:

'expansion_modules':{
    1:{
        'pic_slot': 1,
        'expan_model': 'EX4550VCP'
    },
    2:{ ... }
}

perhaps you should have:

'expansion_modules':[
    {
        'pic_slot': 1,
        'expan_model': 'EX4550VCP'
    },
    { ... }
]