I have a little project that involved article archive browsing by year of publication.
I used the trick given in this other question to build a list of article publication years and article counts for those years. It works pretty well on my test server with SQLite. Since the production server will rely on PostgreSQL I am looking for a way to achieve the same thing in PostgreSQL and ended up toying with the EXTRACT keyword. I use something like "import settings" to detect the current database backend and execute the right query.
My point is all of that look more and more like a dirty & crappy hack to solve an issue in a very inelegant, untestable and poorly maintainable way. As a web programmer beginner I ask my experienced elder,
How would you deal with that correctly ?
As an option to the raw sql:
You can calculate the count per year with the ORM (e.g. How to use Django ORM to get a list by year of all articles with an article count )
Then you store that value somewhere (in a model or in cache ...) in order not to be overwhelmed by the slowness of the ORM calculation.
Related
I am looking for a simple way to create geographical maps in Django, in which I could then select, highlight and annotate countries or groups thereof.
"Annotate": insert a label displaying textual information about the said country.
Is there anything that comes to mind?
Many thanks
EDIT: I checked GeoDjango already and it looks like much work in order to get where I need to. Don't get me wrong: I'm not trying to minimize my own investment in learning new tools, but for this project, I have a trade-off between time allocated to learning and the relative importance of this geographical feature in my app. It's more of a nice-to-have feature I'd like to add to an already 'complete' app. So I wondered whether there exists a 'simpler' python library for this task.
I think this is more of a question for if there is a front-end library to elegantly handle this. However if you need to generate the maps you could try something like this
https://kartograph.org/
I have personally used this http://jvectormap.com/ and found it to be really good.
In your database you could just have a Countries model with any associated information you might need to display, and create a view to handle that appropriately.
I'm trying to find any information if official django is going to support any noSQL DBMS, especially MongoDB. I found a fork of django 1.3 the django-nonrel (a fork of official django) and some other not very reliable projects (failures occur often, according to comments I found on the web). Is django going to support noSQL officially at all?
Perhaps, there are other ways to achieve your goals, besides going noSQL.
In short, if you just need dynamic fields, you have other options. I have an extensive writeup about them in another answer:
Entity–attribute–value model (Django-eav)
PostgreSQL hstore (Django-hstore)
Dynamic models based on migrations (Django-mutant)
Yes, that's not exactly what you've asked for, but that's all that we've currently got.
As you said, forked code is never the best alternative: changes take longer to get into the fork, it might break things... And even with django-nonrel, is not really Django as you loose things like model inheritance, M2M... basically anything that will need to do a JOIN query behind the scenes.
Is Django going to support NoSQL? As far as I know, there's no plans on the roadmap for doing so in the short run. According to Russell Keith-Magee on his talk on PyCon Russia 2013, "NoSQL" is on the roadmap but in the long term, as well as SQLAlchemy. So if you wanna wait, is going to take a long time, I'm afraid.
Anyway, even if it's not ideal, you still can use Django but use something else as a ORM. Nothing stops you from use vanilla Django and something like MongoDB instead of Django ORM.
I'm build a Django app with Neo4j (along with Postgres), I found this Django integration called neo4django, I was wondering if it's possible to use neo4restclient only, like, what would be the disadvantages of not using Neo4django? Does using neo4-rest-client only, give me more flexibility?
When I was creating my models with Neo4Django, it seemed that there is no difference between modeling a graph db and relational db. Am I missing anything?
Thanks!
You can absolutely go ahead with neo4j-rest-client or py2neo, without using neo4django. In the same way, you can use any other database driver you'd like any time using Django, any REST client, etc.
What'll you lose? The model DSL, the built-in querying (eg, Person.objects.filter(name="Mohamed")), the built-in indexing, and the Lucene, Gremlin and Cypher behind that. Some things will be much easier- like setting an arbitrary property on a node- but you'll need to learn more about how Neo4j works.
You'll also lose some of the shortcuts Django provides that work with neo4django, like get_object_or_404() and some of the class-based views that work with querysets.
What'll you gain? Absolute power over the DB, and an easier time tweaking DB performance. Though neo4django isn't nearly as good a lib as some traditional ORMs in the Python sphere, the trade-off of power vs provided ease is similar.
That said, the two can work together- you can drop down from neo4django to the underlying REST client nodes and relationships anytime. Just use model_instance.node to get the underlying neo4j-rest-client node object from a model, and from neo4django.db import connection to get a wrapped neo4j-rest-client GraphDatabase.
On whether you're missing something: neo4django was written to re-use a powerful developer interface- the Django ORM- so it should feel similar to writing models for Postgres. I've written a bit about that odd feeling in the past. I think part of the problem might be that the lib doesn't highlight the graph terminology new graph-interested devs expect- like traversals and pattern matching- and instead dresses those techniques in Django query clothing.
I'd love your thoughts, or to know anything you'd like the library to do that it isn't doing :) Good luck!
I'm trying to solve the relational model in order to make a Django app.
I't will be something like a McDonald's crew scheduler. I mean the grid with colored pins marking who will be working at a given hour a given weekday.
I did try to Google out some example, but I didn't find anything. I need some theory/bibliography in order to build up my model and code it into my app.
Thanks in advance
From the short description, you probably wouldn't have just one model in your app.
From your question I'm assuming you don't have a lot of experience with databases... Here are a few suggestions:
Start here because if you don't understand the basic principles of database design, foreign keys, one-to-one, one-to-many, many-to-many, etc etc etc; you will have a hard time designing your Django models.
It would be nice to learn SQL too. Django models are supposed to insulate you from it, but in reality it is using SQL underneath and knowing SQL will enable you to check and fix performance issues in the future. There are some resources online too. And if you are using SQLite, learn its syntax too.
The above is stuff that you will be able to reuse regardless of the web framework you end up with. Django, Rails, the next big thing... whatever.
Study other people's data models. Here are several different ones - maybe you can find the one you are looking for (employee shifts? shift scheduling?).
Then read the basic django model documentation and really understand it. What django models are doing is mapping python objects to relational database tables (ORM is the acronym; Object Relational Mapping) and this article may very well help you in coming up with good designs.
Don't get discouraged. Everybody had to start somewhere.
Hope you find all you need. Have fun with Django.
I have made a custom report generator for our database (Oracle Berkeley DB engine). Now it's time for me to add more flexibility and I am in dilemma. Do a partial or a fundamental redesign?
Lets assume that I have plenty of time.
I can only read the database, I don't have the right to modify it.
Inspired from Query Anything with SQLite article, I would like to let SQLite engine to do the dirty work (grouping, filtering, etc).
Have you tried it? Any examples? What about performance issues?
It works fine for what I am using it :-) However I don't use it together with another database, just standalone. There's a list of Well-known Users of SQlite on their website.
You need to tell us more about your usecase to make any speculations about performance, but I'd rather make a POC and measure performance Long-held, incorrect programming assumptions
There is a nice quickstart article on the sqlite site.
Here's the C/C++ API Reference.
I assume you should be able to create a temporary SQLite table by initially querying your other DB and inserting the data into the temporary SQLite table. Then you can use different querys on that temporary table to do your grouping, filtering, etc.