I am using django admin application. I just migrated jango 1.9 to Django 3.1.1. And Using python 3.6
During Django migration it would expects an additional arguments as "on_delete". So, I updated this arguments to all my models.
After modified models I just do "makemigrations" and "migrate" this all should fine without any issues.
And, I could see that "last_login" column as missed in my table. When debugging I could see this in migrations file
operations = [
migrations.RemoveField(
model_name='user',
name='last_login',
)]
Questions
Why this column has removed?
How to add this field to user model again
Related
I have an existing app which uses SQLAlchemy for DB access. It works well.
Now I want to introduce DB migrations, and I read alembic is the recommended way. Basically I want to start with the "current DB state" (not empty DB!) as revision 0, and then track further revisions going forward.
So I installed alembic (version 1.7.3) and put
from my_project.db_tables import Base
target_metadata = Base.metadata
into my env.py. The Base is just standard SQLAlchemy Base = sqlalchemy.ext.declarative.declarative_base() within my project (again, which works fine).
Then I ran alembic revision --autogenerate -m "revision0", expecting to see an upgrade() method that gets me to the current DB state from an empty DB. Or maybe an empty upgrade(), since it's the first revision, I don't know.
Instead, the upgrade() method is full of op.drop_index and op.drop_table calls, while downgrade() is all op.create_index and op.create_table. Basically the opposite of what I expected.
Any idea what's wrong?
What's the recommended way to "initialize" migrations from an existing DB state?
OK, I figured it out.
The existing production DB has lots of stuff that alembic revision --autogenerate is not picking up on. That's why its generated migration scripts are full of op.drops in upgrade(), and op.creates in downgrade().
So I'll have to manually clean up the generated scripts every time. Or automate this cleanup Python script cleanup somehow programmatically, outside of Alembic.
Issue:
In order to start in a clean environment for developing stuff for a web app I would appreciate to be able to retrieve some data from an existing DB (let say the 10 first lines of every tables) in order to create a sequelize seed file per table. It will then be possible to seed an empty DB with these data into the corresponding models and migrations.
I have found the tool named sequelize-auto which seems to work fine to generate a model file from an exsting DB (beware of not already having for example a uses.js model ; it will be overwritten !) : https://github.com/sequelize/sequelize-auto.
This tool will create a model file, but neither a migration or a seed file.
Question:
Is there a way to build a seed file from an existing database?
Found this cool module
you can create (dump) seed with command
npx sequeliseed generate table_name --config
https://www.npmjs.com/package/sequeliseed
Following the inputs from the below forum, system properties were specified and customized names for DATABASECHANGELOG & DATABASECHANGELOGLOCK tables were used & setup (on liquibase update execution).
http://forum.liquibase.org/topic/configurable-databasechangelog-table-name
Liquibase version-3.5.1, Database-Oracle 12c, OS-Redhat Linux
But, on subsequent attempts to execute future liquibase updates (against same database schema), the execution fails as its trying to recreate the customized DATABASECHANGELOG table again - failing with Object Name already in use. This does not happen when trying to use the standard liquibase control tables names (i.e. DATABASECHANGELOG & DATABASECHANGELOGLOCK)
Is there an option to skip recreation of customized liquibase control tables OR another fix for this this issue?
Why setting these as system properties?
You can invoke liquibase like the following (or these arguments defined in the properties file):
liquibase <regular arguments > --liquibaseSchemaName=YOUR_SCHEMA \
--databaseChangeLogTableName=YOUR_DBCHANGELOG \
--databaseChangeLogLockTableName=YOUR_DBCHANGELOGLOCK ....
It works fine for us (liquibase 3.5.1, Oracle 12c).
Thanks
The issue was due to the case-sensitivity of the custom table names when executing against oracle databases. Weird error, but its resolved when specifying the value in upper case (via system properties/command line)
Fellows,
I already had a really hard time trying to make a migration from a postgis 1.5 to 2.3. Actually I had many attempts to do that with all version of postgis: 2.0, 2.1, 2.2 and now 2.3.
As I have spent a few weeks with that, and as I am ready to drop that I keep using my old version of postgresql and postgis, I hope my question finds a echo somewhere...
I only want to migrate one table field, a geometry field. So before trying to do that, I would like to hear if any of you have experience with that:
The idea is to select the field from the old postgis (postgresql 9.2, postgis 1.5), and update the table to the new postgis (postgresql 9.6, postgis 2.3).
Anyone can say anything about it?
EDIT---
I have just tryed to import the table I needed, but I got an error:
violation of constraint "enforce_srid_the_geom".
:(
Thanks a lot.
If you need to migrate just a single table with a geometry column and you are getting troubles with the procedure described here http://www.postgis.org/docs/postgis_installation.html#hard_upgrade
I'd suggest a workaround: create a text field in the old db, e.g. wkt_geom, then execute
update tablename set wkt_geom = st_astext(the_geom)
Now drop the geometry column, export the old db and import into the new one. Then, create the geometry column and
update tablename set the_geom = st_geomfromtext(wkt_geom, SRID_HERE)
This question is related to the github issue of Neo4django. I want to create multiple graphs using Neo4j graph DB from Django web framework. I'm using Django 1.4.5, neo4j 1.9.2 and neo4django 0.1.8.
As of now Neo4django doesn't support labeling but the above is my core purpose and I want to be able to create labels from Neo4django. So I went into the source code and tried to tweak it a little to see if I can make this addition. In my understanding, the file 'db/models/properties.py' has class BoundProperty(AttrRouter) which calls gremlin script through function save(instance, node, node_is_new). The script is as follows:
script = '''
node=g.v(nodeId);
results = Neo4Django.updateNodeProperties(node, propMap);
'''
The script calls the update function from library.groovy and all the function looks intuitive and nice. I'm trying to add on this function to support labeling but I have no experience of groovy. Does anyone have any suggestions on how to proceed? Any help would be appreciated. If it works it would be a big addition to neo4django :)
Thank you
A little background:
The Groovy code you've highlighted is executed using the Neo4j Gremlin plugin. First it supports the Gremlin graph DSL (eg node=g.v(nodeId)), which is implemented atop the Groovy language. Groovy itself is a dynamic superset of Java, so most valid Java code will work with scripts sent via connection.gremlin(...). Each script sent should define a results variable that will be returned to neo4django, even if it's just null.
Anyway, accessing Neo4j this way is handy (though will be deprecated I've heard :( ) because you can use the full Neo4j embeddeded Java API. Try something like this to add a label to a node
from neo4django.db import connection
connection.gremlin("""
node = g.v(nodeId)
label = DynamicLabel.label('Label_Name')
node.rawVertex.addLabel(label)
""", nodeId=node_id)
You might also need to add an import for DynamicLabel- I haven't run this code so I'm not sure. Debugging code written this way is a little tough, so make liberal use of the Gremlin tab in the Neo4j admin.
If you come up with a working solution, I'd love to see it (or an explanatory blog post!)- I'm sure it could be helpful to other users.
HTH!
NB - Labels will be properly supported shortly after Neo4j 2.0's release- they'll replace the current in-graph type structure.