Use a model's field as an identifier - orm

Question

I have the following model in OpenERP 7. How to indicate that the isbn field should be the primary key.
from osv import osv, fields
class Book(osv.Model):
""" A book """
_name = 'helloworld.book'
_columns = {
'isbn' : fields.char('ISBN', size=9, requried=True),
'title' : fields.char('Title', size=100, required=True),
'genre' : fields.char('Genre', size=20, required=True),
}

Answer 1

A primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records.
A primary key’s main features are:
It must contain a unique value for each row of data.
It cannot contain null values.
A primary key is either an existing table column or a column that is specifically generated by the database according to a defined sequence.
OpenERP Supports it by Keeping unique sql constraint on field.
_sql_constraints = [
('my_key_value', 'unique(key_value1,key_value2)', 'key value has to be unique !')
]
In your case, As you have chosen Char type of Field, Set sql constraint like this.Add this to your class. and restart the server and check again. You will find primary key's functionality on 'isbn' field.
_sql_constraints = [
('isbn_uniq', 'unique(isbn)', 'ISBN must be unique!'),
]
For case insensitive constraints,
def _check_unique_insesitive(self, cr, uid, ids, context=None):
sr_ids = self.search(cr, uid ,[], context=context)
lst = [x.ibsn.lower() for x in self.browse(cr, uid, sr_ids, context=context) if x.ibsn]
for self_obj in self.browse(cr, uid, ids, context=context):
if self_obj.ibsn and self_obj.ibsn.lower() in lst:
return False
return True
_constraints = [(_check_unique_insesitive, 'Error: ISBN must be unique!', ['ibsn'])]
Hope this will help you. :)