I save an object in a database in python but when I try to print it it just prints the location of the object. How can I print the actual data of the object?
Assuming the object is student with an id as "key" and email, address as the objects data
def getrecord(self,Id):
rec=self.db[Id]
print(rec)
The output I get:
...object at 0x02605B10>
What I would like to see:
"student#gmail.com, central park, new york"
Or something like that.
Looks like rec is a database record object.
What mechanism are you using to retrieve from the database? An ORM like sqlalchemy? Or directly via an interface such as MySQLdb? The api of your library might explain the data better.
You might try something like print rec.__dict__ to see if the values are part of the rec object, such that you could access the individual return parameters directly print '{0}, {1}, {2}'.format(rec.email, rec.address, rec.city).
Also, depending on what environment you're working in, the console in pycharm, pydev/eclipse can give you some insight into the methods and fields on your record object.
Related
I have work in Perl where I am able to get the newly created data object ID by passing the result back to a variable. For example:
my $data_obj = $schema->resultset('PersonTable')->create(\%psw_rec_hash);
Where the $data_obj contains the primary key's column value.
I want to be able to do the same thing using Python 3.7, Flask and flask-mysqldb,
but without having to do another query. I want to be able to use the specific
record's primary key column value for another method.
Python and flask-mysqldb inserts data like so:
query = "INSERT INTO PersonTable (fname, mname, lname) VALUES('Phil','','Vil')
cursor = db.connection.cursor()
cursor.execute(query)
db.connection.commit()
cursor.close()
The PersonTable has a primary key column called, id. So, the newly inserted data row would look
like:
23, 'Phil', 'Vil'
Because there are 22 rows of data before the last inserted data, I don't want to perform a search
for the data, because there could be more than one entry with the same data. However, all I want
the most recent data row.
Can I do something similar to Perl with python 3.7 and flask-mysqldb?
You may want to consider the Flask-SQLAlchemy package to help you with this.
Although the syntax is going to be slightly different from Perl, what you can do is, when you create the model object, you can set it to a variable. Then, when you either flush or commit on the Database session, you can pull up your primary key attribute on that model object you had created (whether it's "id" or something else), and use it as needed.
SQLAlchemy supports MySQL, as well as several other relational databases. In addition, it is able to help prevent SQL injection attacks so long as you use model objects and add/delete them to your database session, as opposed to straight SQL commands.
Okey so currently I'm trying to upsert something in a local mongodb using pymongo.(I check to see if the document is in the db and if it is, update it, otherwise just insert it)
I'm using bulk_write to do that, and everything is working ok. The data is inserted/updated.
However, i would need the ids of the newly inserted/updated documents but the "upserted_ids" in the bulkWriteResult object is empty, even if it states that it inserted 14 documents.
I've added this screenshot with the variable. Is it a bug? or is there something i'm not aware of?
Finally, is there a way of getting the ids of the documents without actually searching for them in the db? (If possible, I would prefer to use bulk_write)
Thank you for your time.
EDIT:
As suggested, i added a part of the code so it's easier to get the general ideea:
for name in input_list:
if name not in stored_names: #completely new entry (both name and package)
operations.append(InsertOne({"name": name, "package" : [package_name]}))
if len(operations) == 0:
print ("## No new permissions to insert")
return
bulkWriteResult = _db_insert_bulk(collection_name,operations)
and the insert function:
def _db_insert_bulk(collection_name,operations_list):
return db[collection_name].bulk_write(operations_list)
The upserted_ids field in the pymongo BulkWriteResult only contains the ids of the records that have been inserted as part of an upsert operation, e.g. an UpdateOne or ReplaceOne with the upsert=True parameter set.
As you are performing InsertOne which doesn't have an upsert option, the upserted_ids list will be empty.
The lack of an inserted_ids field in pymongo's BulkWriteResult in an omission in the drivers; technically it conforms to crud specificaiton mentioned in D. SM's answer as it is annotated as "Drivers may choose to not provide this property.".
But ... there is an answer. If you are only doing inserts as part of your bulk update (and not mixed bulk operations), just use insert_many(). It is just as efficient as a bulk write and, crucially, does provide the inserted_ids value in the InsertManyResult object.
from pymongo import MongoClient
db = MongoClient()['mydatabase']
inserts = [{'foo': 'bar'}]
result = db.test.insert_many(inserts, ordered=False)
print(result.inserted_ids)
Prints:
[ObjectId('5fb92cafbe8be8a43bd1bde0')]
This functionality is part of crud specification and should be implemented by compliant drivers including pymongo. Reference pymongo documentation for correct usage.
Example in Ruby:
irb(main):003:0> c.bulk_write([insert_one:{a:1}])
=> #<Mongo::BulkWrite::Result:0x00005579c42d7dd0 #results={"n_inserted"=>1, "n"=>1, "inserted_ids"=>[BSON::ObjectId('5fb7e4b12c97a60f255eb590')]}>
Your output shows that zero documents were upserted, therefore there wouldn't be any ids associated with the upserted documents.
Your code doesn't appear to show any upserts at all, which again means you won't see any upserted ids.
I am trying to query my postgres database from django, the query I'm using is
s = Booking.objects.all().filter(modified_at__range=[last_run, current_time], coupon_code__in=l)
Now I am changing this object of mine in some ways in my script, and not saving it to the database. What I want to know is that, is it possible to query this object now?
say, I changed my variable as
s.modified_at = '2016-02-22'
Is it still possible to query this object as:
s.objects.all()
or something similar?
The QueryManager is Django's interface to the database (ORM). By definition this means you can only query data that has been stored in the database.
So, in short: "no". You cannot do queries on unsaved data.
Thinking about why you are even asking this, especially looking at the example using "modified_at": why do you not want to save your data?
(You might want to use auto_now=True for your "modified_at" field, btw.)
You could do something like this:
bookings = Booking.objects.all().filter(modified_at__range=[last_run, current_time], coupon_code__in=l)
for booking in bookings:
booking.modified_at = 'some value'
booking.save() # now booking object will have the updated value
I have this model
class Type(models.Model):
type = models.CharField(max_length=50)
value = models.CharField(max_length=1)
And into it, I have some data from an sql file:
INSERT INTO quest_type (type, value) VALUES ('Noun', '1');
INSERT INTO quest_type (type, value) VALUES ('Adjective', '2');
INSERT INTO quest_type (type, value) VALUES ('Duration', '3');
How do I access these values in the python shell? For example, if I know the type, how do I get the value (and vice verse)? I'm not sure how the syntax works.
you should be able to get that with
Type.objects.filter(type=typeImInterestedIn)
A couple of things to be leary of:
-you probably want to avoid manually writing to a DB that you're using an ORM in. It just creates potential for mismatches.
-naming an object Type is little problematic since it's so close to the python native function type.
It's unclear from your question how much about databases you understand, so I apologize if this answer is too basic for you (if so, please edit your question to include information about what actual database engine you're using and show some sample code trying to read from the database).
The SQL file you have is not the same as an SQL database. It is a series of commands that will create records in an SQL database. First you must install and configure a database engine on your machine then "run" that .sql file so that the records are created in the database.
After you have an actual database, you will have to configure Django so that it knows what kind of SQL engine you're using and the name and location of the database.
Finally, once the database is created and Django configured to talk to the engine, you will write python code to instantiate an instance of the Type class, read a record from the database, and inspect the values.
Also, let me point out that Type is a really, really bad name for a class in any programming language, and type and value are both bad names for columns in SQL databases.
If you are using python shell from django (python manage.py shell) firstly You have to import to your namespace your model, so type from my_app.models import Type.
Now if You want to get only one object from db syntax is:
result = Type.objects.get(type='your_query')
If you want to fetch more then one object syntax goes like this:
result = Type.objects.filter(type='your_query')
second method returns list instead of single object
To loop through list after using filter write:
for item in result:
item.value #will print values from matched rows
I have a table which already contains some data in it. Now i want to upload new data from a csv file and want to update some of the previous values of that table. I am using django 1.3 and sqlite3 as database. But i am not able to update the table.
If you do not want to change Primay key values or do not to add new objects to the table, which could be duplicate of the old info - then you need some kind of data which you can use as lookup parameters in your database.
If you have model which represents this data, then its really easy using
m = Model.objects.get(somecolumn = somedata)
m.someothervalue = someotherdata
m.save()
But why include django in this anyway? If you have CSV table, then updating this info is really a case of writing queries. and programs like Excel and openoffice make this very easy.
If you already have data in CSV format, then just open the data as spreadsheet and use excels/openoffice's Concactenate function to create update queries
Update mytable set value1 = data1, value2 = data2 where somevalue = somedata;
If you used openoffice for this, then openoffice has this nifty Text to columns function (under data in program menu), which turns concactenated values into string. Then you can copypaste those strings into command prompt or phppgadmin and run.. and voila, you get updated data in your database.
Edit (In response to you comment.):
Look into this: https://docs.djangoproject.com/en/dev/ref/models/querysets/#get-or-create
If you want to use django for this, then use get_or_create. But you need to remember here, that if any of the parameters you use in get_or_create method have changed, then new object will be created. Thats why i said in the beginning of the post, that you need some kind of data, which will not change.
for example (taken from the link above)
obj, created = Person.objects.get_or_create(first_name='John', last_name='Lennon',
defaults={'birthday': date(1940, 10, 9)})
will create new obj(Person) when used first time. But if used 2nd time and the date has changed, then new Person with same name and last name but new date will be created.
So to avoid this, you'll still need to do something like
obj.someothervalue = someotherdata
obj.save()
if you want to have more control over the data, that could have been changed.
Alan.