I exported a wizard from PostgreSQL and then imported it to MySQL, but the column id changed which crashed the relation among the tables in the database. id is a primary key in my app, and I thought that might be the problem. Is there any method to fix this and keep the id during the migration. Thanks a lot!
I fixed this by dumping the SQL and Data file instead of exporting a wizard. After executing the queries, the database looks good.
Related
I am recreating a web app in Django that was running in a server but it was terminated, fortunately, I did a backup of all the code. My problem comes with the database because but I do not know how to transfer all the data from the old db.sqlite3 Django database web app into the new one.
I found a similar question as mine Django: transfer data from one database to another but the user wanted to transfer data from specific columns because their models.pyfrom the old and new databases were slightly different. In my case, my models.py from the old and new databases are the same.
Alternatives
I am using the DB Browser for SQLite to explore the content of the old database and I could add manually each row into the Django administration but this will take me too much time.
I could copy the old db.sqlite and replace it in the new web app because the models.py file remains the same but this solution is not appropriate IMO, this solution is rude and I think it goes against the good practices of Software.
How should I proceed for transferring data from the old database to the new one?
This seems like a one time copy of one db to another. I don't see how this goes against good software practice unless you have to be copying this db frequently. I've done it before when migrating servers and it doesn't cause any issues assuming the two instances of the application are the same build.
I was able to do some minor tricks in order to solve my problem because there is not a straightforward functionality that allows you to transfer all your data from two sqlite databases in Django. Here is the trick I did:
Download the sqlite db browser to explore and export the contents of your old database in a .csv file. Open you database with sqlite db browser and hit on the tables option and you will see all your tables, then do a right click on any of those and hit the export as a csv file option to generate the csv file (name_of_your_csv_file.csv). The other alternative is to use the sqlite3.exe to open your database in cmd or powershell and then doing the export with:
.tables #this lets you explore your available tables
headers on
mode csv
output name_of_your_csv_file.csv
2.There are two choices up to this point: You can either insert all the records at once to your new database or you can drop your existing tables from the new database and then recreate them and import the .csv file. I went for the drop option because there were more than 100 records to migrate.
# sqlite3
# check the structure of your table so you can re-create it
.schema <table_name>
#the result might be something like CREATE TABLE IF NOT EXISTS "web_app_navigator_table" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "ticket" varchar(120) NOT NULL);
#drop the table
drop table web_app_navigator_table
#re-create the table
create table web_app_navigator_table(id integer not null primary key autoincrement, ticket varchar(120) not null);
#do the import of the csv file
.import C:/Users/a/PycharmProjects/apps/navigator/name_of_your_csv_file.csv table_name_goes_here
You might see an error such as csv:1: INSERT failed datatype mismatch but this indicates that the first row of your csv file was not inserted because it contains the headers of the exported data from your old database.
I am doing a poc in Django and i was trying to create the admin console module for inserting,updating and deleting records through django admin console through models and it was doing fine
I have 2 questions.
1.I need to have model objects for existing tables which needs to be present in a particular schema.say schema1.table1
Here as of now i was doing poc for public schema.
So can it be done in a fixed defined schema and if yes how.Any reference would be very helpful
2.Also i wanted to update few columns in the table through console and the rest of the columns will be done automatically like currentimestamp and created date etc.Is it possible through default django console and if yes kindly share any reference
Steps for 1
What i have done as of now is created a class in model.py with attributes as author,title,body,timeofpost
Then i used sqlmigrate after makemigrations app to create the table and after migrating have been using the admin console for django to insert and update the records for the table created.But this is for POC only.
Now i need to do the same but for existing tables with whom i can interact and insert or update record for those existing tables through admin console.
Also the tables are getting created in public schema by default.But i am using postgres and the existing tables are present in different schemas and i wanted to insert,update and delete for this existing tables.
I am stuck up here as i dont know how to configure model with existing database schema tables through which we can interact through django console and also for different schemas and not in public schema
Steps for 2:
Also i wanted the user to give input for few columns like suppose in this case time of creation is not required to be given as input by user .Rather it should be taken care when the database is updating or creating
Thanks
In order for Django to "interact" with an existing database you need to create a model for it which can be done automatically as shown here. This assumes that your "external" database isn't going to be changed often because you'll have to keep your models in sync which is tricky - there are other approaches if you need that.
As for working with multiple database schemas - is there a reason you can't put your POC table in the same database as the others? Django supports multiple databases, but it will be harder to setup. See here.
Finally, it sounds like you are interested in setting the Django default field attribute. For an example of current time see here.
I have a problem, the debug always says no such table Profile but I did syncdb and checked all the connections what could be the problem other then that?
The most likely problem is that you edited your model and syncdb didn't actually modify the table.
Open your DB client and make sure they match up. Otherwise, drop the table and resync and you should be good
Your models need to match the DB set up or confusion is imminent.
Make sure python manage.py sql myapp looks the same as sql: show schema (myapp)
Source: Hours of frustration :)
I've recently changed the database server on my project from sqlite3 to Postgresql and I have a few questions that I hope will give an answer to my issues.
I understand that switching from sqlite to Postgres implies that I create the new database and the tables inside it, right? I've done that but I haven't seen any new files created in my project to show me that the database I've made is visible. (Btw, I've changed the database name in settings.py)
I probably should mention that I'm working in a virtual environment and I would like to know if that affects my references in any way. I've tried to import the tables in Django to try and count the number of records in a table but I get the error: "No module named psdemo". (psdemo is my database name and i'm trying to import the table with:
from ps.psdemo import Product
where ps is my application, psdemo is my database and Product the table in the database.
In conclusion I'm trying to get access to my database and tables but I can't manage to find them. I repeat, there is no new database file in my project or in my virtual environment (I've searched thoroughly) but if I use a terminal connection I can connect to my virtual environment and change directories to get to the application folder then if I connect to the Postgresql server I can create the database, the tables and can Insert into them, make queries etc, but I cannot access them from the Django code.
I understand that switching from sqlite to Postgres implies that I create the new database and the tables inside it, right? I've done that but I haven't seen any new files created in my project to show me that the database I've made is visible. (Btw, I've changed the database name in settings.py)
All you have to do with postgres is create the database. Not the tables. Django will create the tables, and anything else it thinks are useful, once you call syncdb.
You won't have any new files in your project like you did in sqlite. If you want to view your database, you should download and install pgadminIII (which I would recommend in any event)
I probably should mention that I'm working in a virtual environment and I would like to know if that affects my references in any way. I've tried to import the tables in Django to try and count the number of records in a table but I get the error: "No module named psdemo". (psdemo is my database name and i'm trying to import the table with:
Here, you import models via normal python syntax and it then references your tables. Each model should represent a single table. You define your models first, and then call
python manage.py syncdb
In conclusion I'm trying to get access to my database and tables but I can't manage to find them.
See above, but you should definitely read about postgres installation from the postgres docs, and read the psycopg2 docs as well as the Django docs for setting up a postgres database.
I understand that switching from sqlite to Postgres implies that I
create the new database and the tables inside it, right? I've done
that but I haven't seen any new files created in my project to show me
that the database I've made is visible. (Btw, I've changed the
database name in settings.py)
Database files are not created in the project directory with postgresql. They are created in the database server data directory (like /var/lib/postgres it depends on the distribution). You should generally query it through a PostgreSQL client that connects to the PostgreSQL server rather than messing with the files directly.
You can for example run command:
manage.py dbshell
As to your first issue, see #jpic's answer.
On your second issue, your database is not a package, and you do not import models from your database. If you were able to import your models correctly before you made any changes, change your import statements back to how they were.
I had a table in Postgres called user that was a custom model. I then switched over to the default Django User class, but there have been issues because of the name overlap. How can I either wipe the previous table, or wipe the entire DB (still in testing, so not a big deal) to start over?
The simplest would be to execute a DROP TABLE statement directly in your database prompt, remember that Django models are just like any other table for your database
dropdb --help
Run this in the terminal