How to create a list within list in python

Can you try the following:

data['AgreementIdList'] = [data['AgreementIdList']]
val = data['Required']
if val == 'true':
    val = True    
data['Required'] = val

Assuming you want the following output:

{"AgreementIdList": ["ABC123"], "Required": True}

Now if you want to convert it to json you need to use an additional library. The following will work:

import json
data_list = []
data_list.append(data)
json_data = json.dumps(data_list)
print(json_data)

JSON Output:

'[{"AgreementIdList": ["ABC123"], "Required": true}]'

The json output can be now used to test you API.

I'm assuming you don't necessarily want to mutate the original data.

data = {'AgreementIdList': 'ABC123', 'Required': 'true'}
data2 = dict(data, AgreementIdList=[data['AgreementIdList']])
print(data2)

outputs

{'AgreementIdList': ['ABC123'], 'Required': 'true'}

On more recent Python versions, you can also use this syntax for the same effect:

data = {'AgreementIdList': 'ABC123', 'Required': 'true'}
data2 = {**data, 'AgreementIdList': [data['AgreementIdList']]}

First of all your data is set as a dictonary. You can find this out by running print(type(data)). So what you are actually trying to do is to add a list with one item to a dictionary. Try this:

data = {'AgreementIdList': 'ABC123', 'Required': 'true'}

data['AgreementIdList'] = ['ABC123']

print(data)

For expected result:

data2 = {'AgreementIdList': [data['AgreementIdList']], 'Required':(data['Required']=='true')}
data2
Out[10]: {'AgreementIdList': ['ABC123'], 'Required': True}

You can just make below change to get expected result,

data = {'AgreementIdList': ['ABC123'], 'Required': 'true'}