In Typeorm, migration: generate works fine when I create a new entity file or when I add a new column to the existing entity. But when I delete any entity file from the entities folder, it cannot detect it. For my case this is src/models/*.ts
I think this is a wanted behaviour. What you want is a match between entity and table, when the entity is deleted TypeORM should generate a migration file where the table will be deleted. But there are often tables which have no entity representation, but should not be removed.
In your case you need to manually create an empty migration file typeorm migration:create -c default -n DropTable and drop the table.
Related
I am trying to implement a unique_together constraint on one of the models in my Django project. The decision to have a unique constraint was taken after test data was already created in the table.
Now while running migrations, I came across the following error:
django.db.utils.IntegrityError: UNIQUE constraint failed:
movt_frt.frt_group_id,
movt_frt.rec_loc_id,
movt_frt.dis_loc_id
I have tried creating similar unique constraints on table that previously held no data and migrations happened successfully.
My question is:
Am I right in concluding that the Migration is failing because the table already has data residing in it?
Is there a way to do some changes to the migration file on the lines as discussed here and attempt migration again, to run successfully?
I am using Django ver. 2.0.6
I don't know if this question is still relevant. It's not so much that the table is filled with data. These data already contains combinations that conflict with your specified 'unique_together'.
Overruling is not possible, but if the table is not too big you could correct it manually.
I'v been asked to create an app in Oracle Apex that will allow me to drop a CSV file. The file contains a list of all active physicians and associated info in my area. I do not know where to begin! Requirements:
-after dropping CSV file to apex, remove unnecessary columns
-edit data in each field, ie if phone# > 7 characters and begins with 1, remove 1. Or remove all special characters from a column.
-The CSV contains physicians of every specialty, I only want to upload specific specialties to the database table.
I have a small amount of SQL experience from Uni, and I know some HTML and CSS, but beyond that I am lost. Please help!
Began tutorial on Oracle-Apex. Created upload wizard on a dev environment
User drops CSV file to apex
Apex edits columns to remove unneccesary characteres
Only uploads specific columns from CSV file
Only adds data when column "Specialties" = specific specialties
Does not add redundant data (physician is already located in table, do nothing)
Produces report showing all new physicians added to table
Huh, you're in deep trouble as you have to do some job using a tool you don't know at all, with limited knowledge of SQL language. Yes, it is said that Apex is simple to use, but nonetheless ... you have to know at least something. Otherwise, as you said, you're lost.
See if the following helps.
there's the CSV file
create a table in your database; its description should match the CSV file. Mention all columns it contains. Pay attention to datatypes, column lengths and such
this table will be "temporary" - you'll use it every day to load data from CSV files: first you'll delete all it contains, then load new rows
using Apex "Create page" Wizard, create the "Data loading" process. Follow the instructions (and/or read documentation about it). Once you're done, you'll have 4 new pages in your Apex application
when you run it, you should be able to load CSV file into that temporary table
That's the first stage - successfully load data into the database. Now, the second stage: fix what's wrong.
create another table in the database; it will be the "target" table and is supposed to contain only data you need (i.e. the subset of the temporary table). If such a table already exists, you don't have to create a new one.
create a stored procedure. It will read data from the temporary table and edit everything you've mentioned (remove special characters, remove leading "1", ...)
as you have to skip physicians that already exist in the target table, use NOT IN or NOT EXISTS
then insert "clean" data into the target table
That stored procedure will be executed after the Apex loading process is done; a simple way to do that is to create a button on the last page which will - when pressed - call the procedure.
The final stage is the report:
as you have to show new physicians, consider adding a column (into the target table) which will be a timestamp (perhaps DATE is enough, if you'll be doing it once a day) or process_id (all rows inserted in the same process will share the same value) so that you could distinguish newly added rows from the old ones
the report itself would be an Interactive report. Why? Because it is easy to create and lets you (or end users) to adjust it according to their needs (filter data, sort rows in a different manner, ...)
Good luck! You'll need it.
I have an sql file(we can generate this in whatever way we want).
I want to load it fully initially, then want to update(delete, create) db based using logic.
Later, if I want to delete more, we can simply delete.
But, if we want to add more, then we need to import sql again. Before importing, I cant drop those tables because they are already foreign keys to others. So, I can only do this:
Run sql file somehow to add only non-available entries to database skipping available entries so I can skip errors ( duplicate key value violates unique ).
Import your data to a temporary table and then just use something like:
insert into real_table_name
select * from temporary_table_name
where id not in (select id from real_table_name);
I have a project with existing class model as
class Disability(models.Model):
child = models.ForeignKey(Child,verbose_name=_("Child"))
But with the recent architecture change i have to modify it as
class Disability(models.Model):
child = models.ManyToManyField(Child,verbose_name=_("Child"))
now for this new change .. ( even i have to modify the existing database for the new one )
i guess data migration is the best way to do it rather than doing it manually .
i refered this online doc
http://south.readthedocs.org/en/latest/commands.html#commands-datamigration
but it has very less about data migration . and more about schema migration .
question 1 . if i do the schema migration will this make me loose all me previous data belonging to that old model.
question 2 . Even i am tring for schema migartion it is asking this ...
(rats)rats#Inspiron:~/profoundis/kenyakids$ ./manage.py schemamigration web --auto
? The field 'Disability.child' does not have a default specified, yet is NOT NULL.
? Since you are removing this field, you MUST specify a default
? value to use for existing rows. Would you like to:
? 1. Quit now, and add a default to the field in models.py
? 2. Specify a one-off value to use for existing columns now
? 3. Disable the backwards migration by raising an exception.
? Please select a choice: 1
Can anyone Explain the concept and difference between schema and data migration and how this can be achieved separately .
Schema and data migrations are not different options you can take to modify your table structure. They are completely different things. Of course, data migrations are fully described in the South docs.
Here a data migration will not help you, because you need to modify your schema. And the whole point of South and other migration systems is that they allow you to do that without losing data.
South will try to do a transaction by moving your table data to a temporary table (I could be wrong there), then restructure the table and try to add in the origin data to the new strucutre. Like this:
old_table -> clone -> tmp_table
old_table ->restructure
tmp_table.data -> table
South will look at the field types. If there is big changes it will ask what to do. For example chaning a text field to a int field would be very hard to convert :)
When you remove fields you may still want to be able to convert back to an old structure, so south will need some default data to be able to create a table with the old structure.
Moving data is always an issue since you may change table structure and field type. For example how would you manually deal with data from a Char(max_length=100) to a Char(max_length=50)?
Best suggestion is to keep good backups.
Also take advantage of djangos fixtures. You can save fixtures for different datastructures along with south migrations.
South will load initial_data files in the same way as syncdb, but it
loads them at the end of every successful migration process
http://south.readthedocs.org/en/latest/commands.html#initial-data-and-post-syncdb
I have a table Object that has 2 fields that are foreign keys (user_id and teacher_id). After generating the Entities for the X table, the entity only contain the $user and $teacher properties, which forces me to use the associated objects instead of id. So supposing I know the user_id and teacher_id for my object, instead of doing:
$object->setUserId(1)
I have to do:
$user = $this->getDoctrine()->getRepository('MyBundle:Users')->find(2);
$object->setUser($user)
is there no way to work directly with the ids to avoid retrieving the entire object associated to each id?
The framework suggests to use objects when setting the association value. Still – are you sure the record isn't loaded in the memory already? If it is, it will not cause additional SQL statement execution.
If you really need to update the association without loading the object, you can
run native SQL;
try creating Doctrine Proxy object manually and setting it instead.
You can get the proxy object using EntityManager method getReference:
$object->setUser($this->getDoctrine()->getReference('MyBundle:Users', 2));