title: OperationalError: (1101, BLOB, TEXT, GEOMETRY or JSON column field_name cant have a default value)
body: <p><strong>Work Environment</strong>:<br>
  1. Django 1.11<br>
  2. Python 3.6<br>
  3. MySQL Community Server- 5.7.21<br><br>
  I've been using <a href="https://pypi.org/project/django-jsonfield/" rel="nofollow noreferrer"><code>django-jsonfield</code></a> for my Django models.<br></p>
  
  <pre><code>import jsonfield
  from django.db import models
  
  
  class MySampleModel(models.Model):
      name = models.CharField(max_length=123)
      json_data = jsonfield.JSONField(default={})
  </code></pre>
  
  <p><br>
  As we knew, this particular field doesn't support JSON lookups and aggregation because it created as a <strong><code>LongText</code></strong> in MYSQL backend.<br>
  <br>So, I decided to use <a href="https://django-mysql.readthedocs.io/en/latest/index.html" rel="nofollow noreferrer">Django-MYSQL</a>, which support <a href="https://django-mysql.readthedocs.io/en/latest/model_fields/json_field.html" rel="nofollow noreferrer">JSONField</a> too, hence I changed my <code>models.py</code> as,<br></p>
  
  <pre><code>import jsonfield
  from django.db import models
  from django_mysql.models import JSONField as MYSQLJSONField
  
  
  class MySampleModel(models.Model):
      name = models.CharField(max_length=123)
      json_data = jsonfield.JSONField(default={})
      new_jsonfield = MYSQLJSONField(default=dict)
  </code></pre>
  
  <p><br>
  then I ran <code>makemigrations</code> command and it succesfully excecuted and generated migration file.But, when try to run <code>migrate</code>, it throws the error, as<br></p>
  
  <pre><code>django.db.utils.OperationalError: (1101, "BLOB, TEXT, GEOMETRY or JSON column 'new_jsonfield' can't have a default value")
  </code></pre>
  
  <p><br>
  <strong>Traceback:</strong><br></p>
  
  <pre><code>Running migrations:
    Rendering model states... DONE
    Applying spider.0055_run_new_jsonfield...Traceback (most recent call last):
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
      return self.cursor.execute(sql, params)
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 112, in execute
      return self.cursor.execute(query, args)
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/cursors.py", line 226, in execute
      self.errorhandler(self, exc, value)
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
      raise errorvalue
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/cursors.py", line 217, in execute
      res = self._query(query)
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/cursors.py", line 378, in _query
      rowcount = self._do_query(q)
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/cursors.py", line 341, in _do_query
      db.query(q)
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/connections.py", line 280, in query
      _mysql.connection.query(self, query)
  _mysql_exceptions.OperationalError: (1101, "BLOB, TEXT, GEOMETRY or JSON column 'new_jsonfield' can't have a default value")
  
  The above exception was the direct cause of the following exception:
  
  Traceback (most recent call last):
    File "./manage.py", line 8, in &lt;module&gt;
      execute_from_command_line(sys.argv)
    File "/usr/local/lib/python3.6/site-packages/django/core/management/__init__.py", line 353, in execute_from_command_line
      utility.execute()
    File "/usr/local/lib/python3.6/site-packages/django/core/management/__init__.py", line 345, in execute
      self.fetch_command(subcommand).run_from_argv(self.argv)
    File "/usr/local/lib/python3.6/site-packages/django/core/management/base.py", line 348, in run_from_argv
      self.execute(*args, **cmd_options)
    File "/usr/local/lib/python3.6/site-packages/django/core/management/base.py", line 399, in execute
      output = self.handle(*args, **options)
    File "/usr/local/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 200, in handle
      executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
    File "/usr/local/lib/python3.6/site-packages/django/db/migrations/executor.py", line 92, in migrate
      self._migrate_all_forwards(plan, full_plan, fake=fake, fake_initial=fake_initial)
    File "/usr/local/lib/python3.6/site-packages/django/db/migrations/executor.py", line 121, in _migrate_all_forwards
      state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
    File "/usr/local/lib/python3.6/site-packages/django/db/migrations/executor.py", line 198, in apply_migration
      state = migration.apply(state, schema_editor)
    File "/usr/local/lib/python3.6/site-packages/django/db/migrations/migration.py", line 123, in apply
      operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
    File "/usr/local/lib/python3.6/site-packages/django/db/migrations/operations/fields.py", line 62, in database_forwards
      field,
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/mysql/schema.py", line 50, in add_field
      super(DatabaseSchemaEditor, self).add_field(model, field)
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/schema.py", line 396, in add_field
      self.execute(sql, params)
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/schema.py", line 110, in execute
      cursor.execute(sql, params)
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 79, in execute
      return super(CursorDebugWrapper, self).execute(sql, params)
    File "/usr/local/lib/python3.6/site-packages/raven/contrib/django/client.py", line 123, in execute
      return real_execute(self, sql, params)
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
      return self.cursor.execute(sql, params)
    File "/usr/local/lib/python3.6/site-packages/django/db/utils.py", line 95, in __exit__
      six.reraise(dj_exc_type, dj_exc_value, traceback)
    File "/usr/local/lib/python3.6/site-packages/django/utils/six.py", line 685, in reraise
      raise value.with_traceback(tb)
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
      return self.cursor.execute(sql, params)
    File "/usr/local/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 112, in execute
      return self.cursor.execute(query, args)
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/cursors.py", line 226, in execute
      self.errorhandler(self, exc, value)
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
      raise errorvalue
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/cursors.py", line 217, in execute
      res = self._query(query)
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/cursors.py", line 378, in _query
      rowcount = self._do_query(q)
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/cursors.py", line 341, in _do_query
      db.query(q)
    File "/usr/local/lib/python3.6/site-packages/MySQLdb/connections.py", line 280, in query
      _mysql.connection.query(self, query)
  django.db.utils.OperationalError: (1101, "BLOB, TEXT, GEOMETRY or JSON column 'new_jsonfield' can't have a default value")
  </code></pre>
  
  <p><br>
  <strong>Generated Migration File</strong><br></p>
  
  <pre><code>from __future__ import unicode_literals
  
  from django.db import migrations
  import django_mysql.models
  
  
  class Migration(migrations.Migration):
  
      dependencies = [
          ('app_name', 'some_prev_migrationfile'),
      ]
  
      operations = [
          migrations.AddField(
              model_name='mysamplemodel',
              name='new_jsonfield',
              field=django_mysql.models.JSONField(default=dict),
          ),
      ]
  </code></pre>
  
  <p><br></p>
  
  <h1>Question</h1>
  
  <p>How can I <strong>safely</strong> migrate from <strong><code>django-jsonfield</code></strong> to <strong><code>Django-MYSQL</code></strong> at this context?</p>