CODEWITHSUNDEEP
pythonarraysdictionary
N Raghu
N Raghu

Reputation: 746

python append array in Ordered Dicts with new values

My SQL Structure is like below:

CourseId StudentId CourseName
6001      101      Password
6002      102      Awareness
6003      101      Security

I'm pulling data into tuples using pyodbc cursorand creating list of ordered dicts for processing.

for tup in tuples:
 doc = collections.OrderedDict()
 doc['studentid'] = tup.StudentId
 doc['courses'] = [{courseid: tup.CourseId, 'coursename': tup.CourseName}]
 insArray.append(doc)

Now, if the student Id already exists in any of the ordered array in the insArray list I need to append the course details in the courses array.
For the above given records the expected insArray result would be:

[OrderedDict([('studentid', 101), ('courses', [{'courseid': 6001, 'coursename':'Password'},{'courseid': 6003, 'coursename':'security'}])]), OrderedDict([('studentid', 102), ('courses', [{'courseid': 6002, 'coursename':'Awareness'}])])]

Upvotes: 0

Views: 5146

Answers (1)

Maarten Fabré
Maarten Fabré

Reputation: 7058

Instead of a list insArray as recordset you could use and OrderedDict, and then through the magic of dict.get(key, default) append to a previous list of courses

Code

insArray = collections.OrderedDict()

for tup in tuples:
    student_id = tup.StudentId
    courses = insArray.get(student_id, collections.OrderedDict()).get('courses', list())
    courses.append({'courseid': tup.CourseId, 'coursename': tup.CourseName})  
    # list.append alters the original list and returns None

    doc = collections.OrderedDict()
    doc['studentid'] = student_id
    doc['courses'] =  courses

    insArray[student_id] = doc

Result

OrderedDict([(101,
              OrderedDict([('studentid', 101),
                           ('courses',
                            [{'courseid': 6001, 'coursename': 'Password'},
                             {'courseid': 6003, 'coursename': 'Security'}])])),
             (102,
              OrderedDict([('studentid', 102),
                           ('courses',
                            [{'courseid': 6002,
                              'coursename': 'Awareness'}])]))])

List

If you want a list as insArray, you can retrieve that with list(insArray.values())

Upvotes: 1

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