I can't figure this out, I've done little work before with SQLAlchemy, but Flask SQLAlchemy seems to work very differently, and I can't find much about it online or on the documentation.
Basically, I want to pull one item from the database, and I have done this:
current_word = WordOfDay.query.order_by("WordOfDay.created_date").limit(1)
However, I keep getting the following error:
AttributeError: 'BaseQuery' object has no attribute 'word_of_the_day'
Why does it keep referring to 'BaseQuery' and how can I get around this? Other queries seem to work such as .query.get(id)...
Related
I have to update a lot of data to mysql (~100Mio records!). Some records already exists, some have to be created. I also have to create some nested resources for each record.
I know the activerecord-import gem but as far as i know it can't handle nested records (or only with ugly workarounds). The issue is that I dont know the ID's for all nested records before they are created - and creating them in single queries takes time.
So lets say there is a model called Post and can have many Comments. My current code looks like this:
Post.transaction do
import_posts.each do |import_post|
post = Post.find_or_initialize_by(somevalue: import_post['somevalue']
post.text = import_post['text']
import_post['comments'].each do |import_comment|
comment = post.comments.find_or_initialize_by(someothervalue: import_comment['someothervalue'])
comment.text = import_comment['text']
end
post.save(validate: false) #Dont need validation - saves some time
end
end
This is just an example and it works but its far away from 'damn fast'. Are there any ideas how to speed up the data upload? Am I totally wrong?
Im working with Rails5 and ruby 2.4.
Thanks in advance!
Django 1.11.7
MySQL
I was trying to change the value of an object like this:
# change the value of the filed and save
def patch(...):
instance.field_name = new_name
instance.save()
print(instance.filed_name)
When I run the code I got the print result as new_name. But when I check the database manually I got the result as old_name.
Then I tried ways like:
instance.save(update_fields=['field'])
and
ModelName.objects.filter(id=instance.id).update(field_name=new_name)
but get the above problem as well. And meanwhile, the project runs perfectly functional except for this segment of code.
Any idea what caused this problem or suggestion on how to solve it?
Is that piece of code inside a transaction? Maybe the transaction gets rolledback somewhere later.
When you read from the DB are you inside a transaction? Some transaction modes may not show you this change.
Are you sure that field_name is the correct field name? Maybe you have a typo and you just set a property of the object without changing model field. From what I see you sometimes type "field_name" and sometimes "filed_name"
I've been looking for a way to query the wikipedia api based on a search string for a list of articles with the following properties:
Title
Snippet/Description
One or more images related to the article.
I also have to make the query using jsonp.
I've tried using the list=search parameter
http://en.wikipedia.org/w/api.php?action=query&list=search&prop=images&format=json&srsearch=test&srnamespace=0&srprop=snippet&srlimit=10&imlimit=1
But it seems to ignore the prop=images, I've also tried variations using the prop=imageinfo and prop=pageimages. But they all give me the same result as just using the list=search.
I've also tried action=opensearch
http://en.wikipedia.org/w/api.php?action=opensearch&search=test&limit=10&format=xml
Which gives me exactly what I want when i set format=xml, but returns a simple array of page titles when using format=json and therefore fails because of the jsonp requirement.
Is there another approach to doing this? I'd really like to solve this in a single request rather than make the first search request and then a second request for the images using titles=x|y|z
As Bergi suggested, using generators is the way to go here. Specifically what I would do:
use list=search as a generator, to get the list of articles
use prop=pageimages to get a representative image for each article
use prop=extracts to get a description for each article
The whole query could look like this:
http://en.wikipedia.org/w/api.php?format=json&action=query&generator=search&gsrnamespace=0&gsrsearch=test&gsrlimit=10&prop=pageimages|extracts&pilimit=max&exintro&explaintext&exsentences=1&exlimit=max
I've tried using the list=search parameter, but it seems to ignore the prop=images
If you want to retrieve any properties, you need to specify a list of pages for which you want to get these; e.g. by using the titles=, pageids=, or revids= parameters. You didn't send any, so you did not get a result for the prop=images.
If you did use api.php?action=query&list=search&srsearch=test&prop=images&titles=test you would have gotten the search results for test and the images of the Test page.
You can however also use the collection that the list query generates for your property query, using the list module as a generator. The query would look like
api.php?action=query&generator=search&gsrsearch=test&gsrnamespace=0&gsrprop=snippet&prop=images. Unfortunately, it does not yield the attributes that the list contained, but only used the pageids for a basic property query.
Using two queries is probably the way to go. Btw, I'd recommend to use the pageimages property, it will likely give you the best results.
I wasn't touching the database at all, and the model (named Database) used to work fine. Suddenly, the view I was working with started returning an error: ContentType matching query does not exist http://dpaste.com/1759697/, but for this model only (the same view processes a variety of models.
I jumped into the shell: I can query the model, create a dummy member, retrieve that member, but running a = Database.objects.all() and then try to print a, I get that same error. No idea what is happening. Other tables have no issues. Using mysql.
My base class was Item(models.Model) and then was using Database(Item). I was experimenting with PolymorphicModel for another issue and changed Item to Item(PolymorphicModel). Changing it back fixed the problem; I'm still not sure why only that model was affected (pretty much everything inherited from Item) and why such a weird error occurred, but it works now.
i'm working in a symfony project and using sfPropelPager to show a paged list of elements.
The problem is that with a great amount of data to list (i.e. thousands of registers) it makes a query to the database for each page to show!!!! That means about 100 extra queries in my case, and that is unacceptable.
Showing some of my code: the function that returns the pager object
$pager = new sfPropelPager('MyTable',sfConfig::get('sfPropelPagerLines'));
$c = new Criteria();
$c->add('my_table_field',$value);
$c->addDescendingOrderByColumn('date');
$pager->setCriteria($c);
$pager->init();
return $pager;
So, please, if you know a way to get all the results with only one query, it would be a great solution for my problem. Otherwise i must implement that list with an ajax call for every page the user wants to see
Thank you very much for your time.
I'm not sure to get your problem but, anyway, avoid the use of Criteria. Try to make queries with the ModelCriteria API: http://www.propelorm.org/reference/model-criteria.html.
For each paginated page, a query to the database will be done, this is the standard behavior for all pagers I know. If it's related to related objects (assuming you want to display information from relations), you may want to create a query that links those objects before to paginate, that way you'll get one query per page for all your data to display.
Read this doc for instance: http://www.propelorm.org/documentation/03-basic-crud.html#query_termination_methods
At last i did'nt get a solution for the problem, i had to implement the list via AJAX call, calling to a function that returns the requested page, so at the load of the page, no query for this list is slowing the user experience.
Thank you anyway to help me :)