I have to work with a database containing columns with a dash in their name, as for example a-name. When converting the table with peewee, it converts it to an illegal character, with python complaining about a misplaced operator.
For a table with 2 columns, id and a-name, the result would be
from peewee import *
database = MySQLDatabase('databasename', **{'password': 'pwd', 'host': 'ip', 'user': 'username'})
class BaseModel(Model):
class Meta:
database = database
class ATable(BaseModel):
id = PrimaryKeyField()
a-name = CharField()
class Meta:
db_table = 'aTable'
I found a temporary workaround by changing the dash to an underscore and using the optional parameter db_column, like
a_name = CharField(db_column='a-name')
Is there another possibility for this issue as I do not want to do manual changes everytime I download the models from the database server?
I should add that I have no control over the database server, I have merely an account with read-only permissions.
Greetings,
Luc
a_name = CharField(db_column='a-name')
This is the correct way to solve the problem. Python does not allow dashes in identifiers, so if your column uses them then specify the column name explicitly and use a nice name for the column.
I suppose you could look into modifying the playhouse.reflection.Introspector.make_column_name method, as well.
Related
I have a model B with a Many2many field referencing model A.
Now given an id of model A, I try to get the records of B that reference it.
Is this possible with Odoo search domains? Is it possible doing some SQL query?
Example
class A(models.Model):
_name='module.a'
class B(models.Model):
_name='module.b'
a_ids = fields.Many2many('m.a')
I try to do something like
a_id = 5
filtered_b_ids = self.env['module.b'].search([(a_id,'in','a_ids')])
However, this is not a valid search in Odoo. Is there a way to let the database do the search?
So far I fetch all records of B from the database and filter them afterward:
all_b_ids = self.env['module.b'].search([])
filtered_b_ids = [b_id for b_id in b_ids if a_id in b_id.a_ids]
However, I want to avoid fetching not needed records and would like to let the database do the filtering.
You should create the equivalent Many2many field in A.
class A(models.Model):
_name='module.a'
b_ids = fields.Many2many('module.b', 'rel_a_b', 'a_id', 'b_id')
class B(models.Model):
_name='module.b'
a_ids = fields.Many2many('module.a', 'rel_a_b', 'b_id', 'a_id')
In the field definition, the second argument is the name of the association table, and the two next ones are the name of the columns referencing the records of the two models. It's explained in the official ORM documentation.
Then you just have to do my_a_record.b_ids.
If you prefer doing an SQL request because you don't want to add a python field to A, you can do so by calling self.env.cr.execute("select id from module_b b, ...").fetchall(). In your request you have to join the association table (so you need to specify a name for it and its columns, as described in my code extract, otherwise they are automatically named by Odoo and I don't know the rule).
I think it's still possible to use search domains without the field in A but it's tricky. You can try search([('a_ids','in', [a_id])]) but I'm really not sure.
class A(models.Model):
_name='module.a'
class B(models.Model):
_name='module.b'
a_ids = fields.Many2many('module.a')
Now you want to search a_id = 5
To do so simply use browse or search ORM methods i.e,
a_id = 5
filtered_b_ids = self.env['module.b'].search([(a_id,'in',self.a_ids.ids)])
or
a_id = 5
filtered_b_ids = self.env['module.a'].search([(a_id)])
I am creating a small database for 'trial', per se. I have tried a few setting outs ([{key: value}, {key: value}]. But, I need a solution that can be called by an ID (12345), a name (Rob Alsod), an area (A4 (Like an apartment building)), or a job (Manager, Administrator, etc). So, something like a dictionary (which can only be called by one key) will not work. I tried making a 'Person' class, but I need a way to easily keep track of the classes, and also to assign them easily. For example,
for whatever in whatever:
what = Person(name = 'Rob Alsod', id = 12345, job = 'Admin', area = 'A1') # What can I make this iterate with? (Badly formed question)
My point is, as it loops through, I cannot assign it to the same thing again and again.
Could someone try to make sense of what I am saying, and suggest a way to format my database?
You could easily use SQLAlchemy with SQLite. SQL queries are only a few lines of code away:
from sqlalchemy import *
db = create_engine('sqlite:///people.db')
metadata = MetaData()
user = Table('people', metadata,
Column('ID', Integer, primary_key = True),
Column('name', String(16), nullable = False),
Column('area', String(16)),
Column('job', String(60))
)
After that it is easy connection = db.connect(); result = connection.execute("select ID from people")
On Linux, pip and apt-get make the install a breeze as well.
HTH, Phil
If you want small database for storing any objects identified by key you can use shelve module:
http://docs.python.org/3.2/library/shelve.html
I'm accessing emails in my email server, taking the body of each email and then applying regular expressions to find the data necessary to populate my Django model.
This all works fine except for one field, which is linked as a foreign key to another model field. Despite the value in my email being the same as the one in listed in my other model, it fails....
The error:
ValueError: Cannot assign "'Humanities'": "Subject.faculty" must be a "Faculty" instance.
For example, say each school subject has to be part of a faculty. When populating the database via a form, for the Subject's faculty field I drop down the menu to a list of faculty values/instances as there is a foreign key relationship defined in my model i.e. for the faculty field I can choose from Humanities, Art, Design Technology etc.
But when I find the value 'Humanities' in my email and try to add it to the database model, I get the error above.
Anyone shed any light on this? Am I being stupid or is it more than a ValueError as to me, the values are the same in both cases
Thank you
More code as requested:
class Faculty(models.Model):
name = models.CharField(primary_key=True, max_length=50)
leader = models.CharField(max_length=50)
email = models.EmailField()
mailing_list = models.ManyToManyField("Contact", null=True)
class Subject(models.Model):
name = models.CharField(max_length=50)
faculty = models.ForeignKey(Faculty, to_field="name")
faculty_head = models.CharField(max_length=50)
It sounds like you are trying to assign a string "Humantities" to a ForeignKey relationship. This doesn't make sense. You need to either find or create the actual Faculty object with the name "Humanities" and assign it to the Subject. Something like this in your view (depending on how your form is set up):
if form.is_valid():
faculty_str = form.cleaned_data['faculty']
(faculty, was_created) = Faculty.objects.get_or_create(name=faculty_str, ...)
# It's hard to tell if you are using a ModelForm or just a normal Form. Anyway, assume we already have access to the Subject object
subject.faculty = faculty
subject.save()
get_or_create()
Your value is 'Humanities' perhaps you mean to search for Humanities (without quotes).
You need to create a Faculty instance first.
faculty = Faculty(name='', leader='', email='')
faculty.save()
subject.faculty = faculty
subject.save()
I have a Spring application which uses JPA (Hibernate) initially created with Spring Roo. I need to store Strings with arbitrary length, so for that reason I've annotated the field with #Lob:
public class MyEntity{
#NotNull
#Size(min = 2)
#Lob
private String message;
...
}
The application works ok in localhost but I've deployed it to an external server and it a problem with encoding has appeared. For that reason I'd like to check if the data stored in the PostgreSQL database is ok or not. The application creates/updates the tables automatically. And for that field (message) it has created a column of type:
text NOT NULL
The problem is that after storing data if I browse the table or just do a SELECT of that column I can't see the text but numbers. Those numbers seems to be identifiers to "somewhere" where that information is stored.
Can anyone tell me exactly what are these identifiers and if there is any way of being able to see the stored data in a #Lob columm from a pgAdmin or a select clause?
Is there any better way to store Strings of arbitrary length in JPA?
Thanks.
I would recommend skipping the '#Lob' annotation and use columnDefinition like this:
#Column(columnDefinition="TEXT")
see if that helps viewing the data while browsing the database itself.
Use the #LOB definition, it is correct. The table is storing an OID to the catalogs -> postegreSQL-> tables -> pg_largeobject table.
The binary data is stored here efficiently and JPA will correctly get the data out and store it for you with this as an implementation detail.
Old question, but here is what I found when I encountered this:
http://www.solewing.org/blog/2015/08/hibernate-postgresql-and-lob-string/
Relevant parts below.
#Entity
#Table(name = "note")
#Access(AccessType.FIELD)
class NoteEntity {
#Id
private Long id;
#Lob
#Column(name = "note_text")
private String noteText;
public NoteEntity() { }
public NoteEntity(String noteText) { this.noteText = noteText }
}
The Hibernate PostgreSQL9Dialect stores #Lob String attribute values by explicitly creating a large object instance, and then storing the UID of the object in the column associated with attribute.
Obviously, the text of our notes isn’t really in the column. So where is it? The answer is that Hibernate explicitly created a large object for each note, and stored the UID of the object in the column. If we use some PostgreSQL large object functions, we can retrieve the text itself.
Use this to query:
SELECT id,
convert_from(loread(
lo_open(note_text::int, x'40000'::int), x'40000'::int), 'UTF-8')
AS note_text
FROM note
I'm working with a legacy DB in MSSQL. We have a table that has two columns that are causing me problems:
class Emp(models.Model):
empid = models.IntegerField(_("Unique ID"), unique=True, db_column=u'EMPID')
ssn = models.CharField(_("Social security number"), max_length=10, primary_key=True, db_column=u'SSN') # Field name made lowercase.
So the table has the ssn column as primary key and the relevant part of the SQL-update code generated by django is this:
UPDATE [EMP] SET [EMPID] = 399,
.........
WHERE [EMP].[SSN] = 2509882579
The problem is that EMP.EMPID is an identity field in MSSQL and thus pyodbc throws this error whenever I try to save changes to an existing employee:
ProgrammingError: ('42000', "[42000] [Microsoft][SQL Native Client][SQL Server]C
annot update identity column 'EMPID'. (8102) (SQLExecDirectW); [42000] [Microsof
t][SQL Native Client][SQL Server]Statement(s) could not be prepared. (8180)")
Having the EMP.EMPID as identity is not crucial to anything the program, so dropping it by creating a temporary column and copying, deleting, renaming seems like the logical thing to do. This creates one extra step in transferring old customers into Django, so my question is, is there any way to prevent Django from generating the '[EMPID] = XXX' snippet whenever I'm doing an update on this table?
EDIT
I've patched my model up like this:
def save(self, *args, **kwargs):
if self.empid:
self._meta.local_fields = [f for f in self._meta.local_fields if f.name != 'empid']
super().save(*args, **kwargs)
This works, taking advantage of the way Django populates it's sql-sentence in django/db/models/base.py (525). If anyone has a better way or can explain why this is bad practice I'd be happy to hear it!
This question is old and Sindri found a workable solution, but I wanted to provide a solution that I've been using in production for a few years that doesn't require mucking around in _meta.
I had to write a web application that integrated with an existing business database containing many computed fields. These fields, usually computing the status of the record, are used with almost every object access across the entire application and Django had to be able to work with them.
These types of fields are workable with a model manager that adds the required fields on to the query with an extra(select=...).
ComputedFieldsManager code snippet: https://gist.github.com/manfre/8284698
class Emp(models.Model):
ssn = models.CharField(_("Social security number"), max_length=10, primary_key=True, db_column=u'SSN') # Field name made lowercase.
objects = ComputedFieldsManager(computed_fields=['empid'])
# the empid is added on to the model instance
Emp.objects.all()[0].empid
# you can also search on the computed field
Emp.objects.all().computed_field_in('empid', [1234])