How return list on Python and Flask? [duplicate]

Question

I'm trying to return this list in flask. Teacher is a class and returns objects.

@app.route('/v1/teachers', methods=['GET'])
def getTeachers():
  teachers = []
  for teacher in Teacher.objects:
    teachers.append(teacher)
  return teachers

This code returns the typical error of TypeError: 'list' object is not callable The view function did not return a valid response.

I'm going crazy and I don't know what's going on. Does anyone know?

Thank you!!

EDIT:

I've already worked it out. The problem was not how to return the list, the problem was the serialization in JSON of the objects.

@app.route('/v1/teachers', methods=['GET'])
def getTeachers():
  teachers = []
  for teacher in Teacher.objects:
     teacherJson = teacher.to_json()
     teacherData = json.loads(teacherJson)
     teachers.append(teacherData)
  return jsonify({'teachers': teachers})

Thanks for your help.

Have you tried checking the value in Teacher.objects ? Also, you might need to return response in json. So, you will need to pass this list in json format. — Sumit S Chawla
– Sumit S Chawla, Commented Jan 2, 2019 at 9:20
This doesn't work, it gives me back this error: TypeError: <Teacher: Teacher object> is not JSON serializable — laurajaime
– laurajaime, Commented Jan 2, 2019 at 14:55

shijin · Accepted Answer · 2019-01-02 09:25:28Z

27

You can't return a list directly from flask view.please try to jsonify

from flask import jsonify
@app.route('/v1/teachers', methods=['GET'])
def getTeachers():
   teachers = []
   for teacher in Teacher.objects:
      teachers.append(teacher)
   return jsonify(teachers)

answered Jan 2, 2019 at 9:25

shijin

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3 Comments

ajbraus Over a year ago

Does not work TypeError: Object of type List is not JSON serializable

kmui2 Over a year ago

This works at least for python 2.

sid0972 Over a year ago

@ajbraus take a look here stackoverflow.com/questions/16586180/…

ybl · Accepted Answer · 2022-09-02 07:31:26Z

5

You are returning a list, Flask expects a response to be returned.

from flask import jsonify

@app.route('/v1/teachers', methods=['GET'])
def getTeachers():
  teachers = []
  for teacher in Teacher.objects:
    teachers.append(teacher)
  return jsonify({"teachers": teachers})

edited Sep 2, 2022 at 7:31

answered Jan 2, 2019 at 9:27

ybl

1,63512 silver badges17 bronze badges

4 Comments

laurajaime Over a year ago

This doesn't work, it gives me back this error: TypeError: <Teacher: Teacher object> is not JSON serializable

ajbraus Over a year ago

This does not work.

ybl Over a year ago

You can see the edit from OP in his answer. The teacher object has to be converted to JSON here if it's not automatically convertible.

D.Snap Over a year ago

def test(): test = ['1','2','3'] return jsonify({'test':test})

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