Creating JSON string from database query output

Question

I'm try to create a simple JSON object from the output of a database query that would look something like this:

json_obj= {
           '1': 'test_1',
           '2': 'test_2',
           '3': 'test_3',
           '4': 'test_4',
           '5': 'test_5',
           }

So far I've been trying for loops and json.dumps but cannot get it right:

cat_list = []
cats = Category.query.all()
for cat in cats:
    item = {
            cat.id: cat.name
           }
    cat_list.append(item)

json_cat_list = json.dumps(cat_list)

This does create a JSON object but not exactly what I'm looking for.

json_obj= {
           {'1': 'test_1'},
           {'2': 'test_2'},
           {'3': 'test_3'},
           {'4': 'test_4'},
           {'5': 'test_5'},
           }

Any suggestions on how to do this?

Many thanks

cs95 · Accepted Answer · 2018-03-21 15:55:00Z

5

You want a single dict object, not a list of them.

cat_dict = {}                         # 1
for cat in Category.query.all():
    cat_dict[cat.id] = cat.name       # 2

json_cat_dict = json.dumps(cat_dict)  # 3

Or, (as @Daniel Roseman mentioned below) for conciseness, you can condense everything into a single dictionary comprehension:

cat_dict = {cat.id: cat.name for cat in Category.query.all()}

edited Mar 21, 2018 at 15:55

answered Mar 21, 2018 at 15:44

cs95

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1 Comment

Daniel Roseman Over a year ago

Or as a single-line dict comprehension: cat_dict = {cat.id: cat.name for cat in Category.query.all()}.

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