I need to delete an object from the list of objects based on the condition.
In the selectDoctor method, I need to remove the object from the list in which its docid is equal to the given id and return the removed list.
class Doctor:
def __init__(self, docid, docname, deptname):
self.docid = docid
self.docname = docname
self.deptname = deptname
class Hospital:
def selectDoctor(id,doclist):
for i in range(0, len(doclist)):
if doclist[i].docid==id: //in this condition I need to remove that object from list
doclist.remove(i) //by removing like this it is showing error
return doclist
for i in range(5):
docid=int(input())
docname=input()
deptname=input()
doclist.append(Doctor(docid,docname,deptname)
id=int(input())
res=Hospital.selectDoctor(id,doclist)
print(res)
Using list in Python3, it,s easy to achieve this using following statements(you have at least three possibilities):
Remove by specifying the item index
doclist.pop(i)
OR
Remove by specifying the item(s) index(es) (also range of indexes also allowed e.g. del doclist[0:2] for removing first three items of given list) using the keyword del
del doclist[i]
Remove by specifying the item itself
doclist.remove(doclist[i])
Reference: https://docs.python.org/3.8/tutorial/datastructures.html
Feel free to upvote the answer after fixing your error...
Related
I have created an event listener to capture changes to instances on one of my tables, like so:
Can someone kindly explain to me what the History class is and, more importantly, why the added and deleted attributes are lists?
#event.listens_for(Model, 'before_update')
def model_update(mapper, connection, target):
""" signal when a Model is updated """
# get state of model:
state = inspect(target)
# check for changes:
for attr in state.attrs:
# get history:
hist = attr.load_history() # <-- what is this class?
# add changes to dictionary:
old_value = hist.deleted # <-- why is this a list?
new_value = hist.added # <-- why is this a list?
For context, I am trying to capture the changes to my models and save these changes to a different table (i.e. version history). Is it okay to do something like hist.deleted.pop()? Will hist.deleted always be a list? When, if ever, will it contain more than one item?
Further details: When I update an instance like so:
instance = db.query(Model).get(...)
old_value = instance.some_field
new_value = "NEW"
instance.some_field = new_value
db.add(instance)
db.commit()
print("old_value:", old_value)
print("new_value:", new_value)
This will print:
old_value: OLD
new_value: NEW
But using history, these values will show up in a list:
old_value: ["OLD"]
new_value: ["NEW"]
What is attr.load_history() ?
Returns the current pre-flush change history for this attribute, via the History interface.
This represents a History interface. It returns the history of pre-flush changes (for the requested attribute).
Each time the session is flushed, the history for each attribute is reset. (By default, the session is automatically flushed each time a request is invoked)
What is hist.deleted and hist.added ?
Representation of changes that have occurred on an attribute.
There are 3 of them: added, unchanged and deleted:
added : the collection of elements added to the attribute
unchanged : the collection of elements that have not changed on the attribute
deleted : the collection of elements that have been deleted from the attribute
They are CONSTANTLY represented as an iterable sequence
I created a custom class Node and was able to successfully add an instance of it as dictionary Key.
#This code works
class Node:
def __init__(self,dataval=None):
self.val = dataval
self.nextval = None
NodeA = Node(10)
dictNodeA = {NodeA:'ten'}
#This code works
But when I tried adding List as Key, it gave error.
listA = [10]
dictListA = {listA:'ten'}
##TypeError: unhashable type: 'list'
I want to understand the reason for this difference, as both the object and list are mutable. So why it doesn't work in case of list but works in case of object.
In my items.py:
class NewAdsItem(Item):
AdId = Field()
DateR = Field()
AdURL = Field()
In my pipelines.py:
import sqlite3
from scrapy.conf import settings
con = None
class DbPipeline(object):
def __init__(self):
self.setupDBCon()
self.createTables()
def setupDBCon(self):
# This is NOT OK!
# I want to get the items already HERE!
dbfile = settings.get('SQLITE_FILE')
self.con = sqlite3.connect(dbfile)
self.cur = self.con.cursor()
def createTables(self):
# OR optionally HERE.
self.createDbTable()
...
def process_item(self, item, spider):
self.storeInDb(item)
return item
def storeInDb(self, item):
# This is OK, I CAN get the items in here, using:
# item.keys() and/or item.values()
sql = "INSERT INTO {0} ({1}) VALUES ({2})".format(self.dbtable, ','.join(item.keys()), ','.join(['?'] * len(item.keys())) )
...
How can I get the item list names (like "AdId" etc) from items.py, before process_item() (in pipelines.py) is executed?
I use scrapy runspider myspider.py for execution.
I already tried to add "item" and/or "spider" like this def setupDBCon(self, item), but that didn't work, and resulted in:
TypeError: setupDBCon() missing 1 required positional argument: 'item'
UPDATE: 2018-10-08
Result (A):
Partially following the solution from #granitosaurus I found that I can get the item keys as a list, by:
Adding (a): from adbot.items import NewAdsItem to my main spider code.
Adding (b): ikeys = NewAdsItem.fields.keys() within the Class of above.
I could then access the keys from my pipelines.py via:
def open_spider(self, spider):
self.ikeys = list(spider.ikeys)
print("Keys in pipelines: \t%s" % ",".join(self.ikeys) )
#self.createDbTable(ikeys)
However, there were 2 problems with this method:
I was not able to get the ikeys list, into the createDbTable(). (I kept getting errors about missing arguments here and there.)
The ikeys list (as retrieved) was re-arranged and did not keep the order of the items, as they appear in items.py, which partially defeated the purpose. I still don't understand why these are out of order, when all docs says that Python3 should keep the order of dicts and lists etc. While at the same time, when using process_item() and getting the items via: item.keys() their order remain intact.
Result (B):
At the end of the day, it turned out too laborious and complicated to fix (A), so I just imported the relevant items.py Class into my pipelines.py, and use the item list as a global variable, like this:
def createDbTable(self):
self.ikeys = NewAdsItem.fields.keys()
print("Keys in creatDbTable: \t%s" % ",".join(self.ikeys) )
...
In this case I just decided to accept that the list obtained seem to be alphabetically sorted, and worked around the issue by just changing the key names. (Cheating!)
This is disappointing, because the code is ugly and contorted.
Any better suggestions would be much appreciated.
Scrapy pipelines have 3 connected methods:
process_item(self, item, spider)
This method is called for every item pipeline component.
process_item() must either: return a dict with data, return an Item (or any descendant class) object, return a Twisted Deferred or raise DropItem exception. Dropped items are no longer processed by further pipeline components.
open_spider(self, spider)
This method is called when the spider is opened.
close_spider(self, spider)
This method is called when the spider is closed.
https://doc.scrapy.org/en/latest/topics/item-pipeline.html
So you can only get access to item in process_item method.
If you want to get item class however you can attach it to spider class:
class MySpider(Spider):
item_cls = MyItem
class MyPipeline:
def open_spider(self, spider):
fields = spider.item_cls.fields
# fields is a dictionary of key: default value
self.setup_table(fields)
Alternative you can lazy load during process_item method itself:
class MyPipeline:
item = None
def process_item(self, item, spider):
if not self.item:
self.item = item
self.setup_table(item)
I am currently taking some computer science courses in school and have come to a dead end and need a little help. Like the title says, I need of create a list of Class objects from a file with objects that have a duplicate not added to the list, I was able to successfully do this with a python set() but apparently that isn't allowed for this particular assignment, I have tried various other ways but can't seem to get it working without using a set. I believe the point of this assignment is comparing data structures in python and using the slowest method possible as it also has to be timed. my code using the set() will be provided.
import time
class Students:
def __init__(self, LName, FName, ssn, email, age):
self.LName = LName
self.FName = FName
self.ssn = ssn
self.email = email
self.age = age
def getssn(self):
return self.ssn
def main():
t1 = time.time()
f = open('InsertNames.txt', 'r')
studentlist = []
seen = set()
for line in f:
parsed = line.split(' ')
parsed = [i.strip() for i in parsed]
if parsed[2] not in seen:
studentlist.append(Students(parsed[0], parsed[1], parsed[2], parsed[3], parsed[4]))
seen.add(parsed[2])
else:
print(parsed[2], 'already in list, not added')
f.close()
print('final list length: ', len(studentlist))
t2 = time.time()
print('time = ', t2-t1)
main()
A note, that the only duplicates to be checked for are those of the .ssn attribute and the duplicate should not be added to the list. Is there a way to check what is already in the list by that specific attribute before adding it?
edit: Forgot to mention only 1 list allowed in memory.
You can write
if not any(s.ssn==parsed[2] for s in studentlist):
without committing to this comparison as the meaning of ==. At this level of work, you probably are expected to write out the loop and set a flag yourself rather than use a generator expression.
Since you already took the time to write a class representing a student and since ssn is a unique identifier for the instances, consider writing an __eq__ method for that class.
def __eq__(self, other):
return self.ssn == other.ssn
This will make your life easier when you want to compare two students, and in your case make a list (specifically not a set) of students.
Then your code would look something like:
with open('InsertNames.txt') as f:
for line in f:
student = Student(*line.strip().split())
if student not in student_list:
student_list.append(student)
Explanation
Opening a file with with statement makes your code more clean and
gives it the ability to handle errors and do cleanups correctly. And
since 'r' is a default for open it doesn't need to be there.
You should strip the line before splitting it just to handle some
edge cases but this is not obligatory.
split's default argument is ' ' so again it isn't necessary.
Just to clarify the meaning of this item is that the absence of a parameter make the split use whitespaces. It does not mean that a single space character is the default.
Creating the student before adding it to the list sounds like too
much overhead for this simple use but since there is only one
__init__ method called it is not that bad. The plus side of this
is that it makes the code more readable with the not in statement.
The in statement (and also not in of course) checks if the
object is in that list with the __eq__ method of that object.
Since you implemented that method it can check the in statement
for your Student class instances.
Only if the student doesn't exist in the list, it will be added.
One final thing, there is no creation of a list here other than the return value of split and the student_list you created.
This is my structure:
class Imprint_Location(models.Model):
_name = 'imprint.location'
name = fields.Char()
product_id = fields.Many2one('product.template')
class Imprint_Charges(models.Model):
_name = 'imprint.charge'
_rec_name = 'location_id'
product_id_c = fields.Many2one('product.template', required=True)
location_id = fields.Many2one('imprint.location', required=True)
#api.multi
#api.onchange('product_id_c', 'location_id')
def product_filter(self):
res = {}
print '\n\n-------\n\n', self, self.product_id_c, '\n\n-------\n\n'
if self.product_id_c:
res['domain'] = {'location_id': [('product_id', '=', self.product_id_c.id)]}
print res
return res
class Product_Template(models.Model):
_inherit = 'product.template'
imprint_location_ids = fields.One2many('imprint.location', 'product_id')
sale_imprint_charge_ids = fields.One2many('imprint.charge', 'product_id_c')
Now i have defined a page in product.template and inside the page is sale_imprint_charge_ids which is in <tree editable="bottom"> and i am not selecting the product_id_c field[also this field doesn't show up in the tree defined].
Now my problem here is that when i select this from the form view which i defined for imprint.charge the method product_filter works fine, but when i enter from the product.template then i get a error saying
TypeError: <odoo.models.NewId object at 0x7fbb8bc21b90> is not JSON serializable
Because from product.template if passes the object <odoo.models.NewId object at 0x7fbb8bc21b90> , so if print self.product_id_c then it prints product.template(<odoo.models.NewId object at 0x7fbb8bc21b90>) so this is not serializable. i have tried doing self.product_id_c.ids which give output empty list [].
So how do get the product.template id from the object or pass the id itself overriding some method.
You should improve couple of following points.
res['domain'] = {'location_id': [('product_id', '=', self.product_id_c.id)]}
return res
study some search() method of ORM
Try with following code:
#api.multi
#api.onchange('product_id_c', 'location_id')
def product_filter(self):
res = {}
if self.product_id_c:
self.location_id = False
#search product_template in imprint.locationwith table and limit we will get only record if related record found
location_id = self.env['imprint.location'].search([('product_id', '=', self.product_id_c.id)], limit=1)
if location_id:
#location_id.ids will give you something like [2] so we need to set value as 2
self.location_id = location_id.ids[0]
EDIT:
As per your first comment, you need a list of related location then we should following trick.
Remove product_filter() method
Add domain in imprint.charge object view file
For example:
<field name="location_id" domain="[('product_id', '=', product_id_c)]"/>
Afterwards, Restart Odoo server and upgrade your custom module.
When creating a brand new record Odoo creates that wierd <odoo.models.NewId object at 0x7fbb8bc21b90> object. After you have written the record this id gets turned into the normal ids that you are used to (an integer). In this situation you have a function which (not unreasonably) expects a real id value at a point when no such value really exists. You need to provide a fallback, such as evaluating if the id is an integer and providing an alternate value in that circumstance. Although your function seems to return an object which I dont quite know what you are expecting to happen. If you wish to modify the value of one of your fields I would modify the values of the self object rather that returning an object.