I'm developing an web app with Django to query and download data from multiple weather stations. It's almost everything good but something that I don't like it's that when I filter by stations, the form passes them to the URL like this:
https://my-server/stations?station_name=1&station_name=2&station_name=3
And since the number of selected stations can reach more than 250 (this added to the fact that spatial data are also passed in the URL as coordinates, polygons...), I would like to know if there is any way to obtain the "station_name" parameter in a list format like this or similar, for me to later divide it in my views.py:
https://my-server/stations?station_name=1%3B2%3B3
On the other hand, I'm not sure if there are any contraindications when generating too long URLs, if not I have no problem maintaining the current format, but otherwise I would like to find a solution.
Thanks in advance
Edit: If it helps, I'm using the Select2MultipleWidget widget for this field.
Related
I'm stuck on how to approach the design of this problem - or even how to search for answers. I'm still a bit new with Django. The goal is to have a user select one or more locations (libraries in my problem) from a list of locations. I'd like the user to be able to type in an address and then have the list of locations filter based on distance between the locations. I envision the list of locations to be selection field. I'm assuming there will be an input field for the distance (canned choices or just a whole number) and a button to apply the filter.
I know how to get the user's location (as a postal address) converted to lat/long using py-geocoder. I have the lat/long of each library. I know how to calculate the distance between two points (py-haverstine or maybe geometry-distance).
Where this seems squirrely is the mechanics of filtering the list. How would I do the "filter" action (submit) versus the "save" action if I'm using a model based view? So far, when I hit the server, I've been processing the form as a submission, not a portion.
Or would this be better done client-side as js (which I don't know, but I assume someone has done this already)?
I am working with Django and I am a bit lost on how to extract information from models (tables).
I have a table containing different information from various sensors. What I would like to know is if it is possible from the Django models to obtain for each sensor (each sensor has an identifier) the last row of data (using the timestamp column).
In sql it would be something like this, (probably the query is not correct but I think you can understand what I'm trying)
SELECT sensorID,timestamp,sensorField1,sensorField2
FROM sensorTable
GROUP BY sensorID
ORDER BY max(timestamp);
I have seen that the group_by() function exists and also lastest() but I don't get anything coherent and I'm also not clear if I'm choosing the best form.
Can anyone help me get started with this topic? I imagine it is very easy but it is a new world and it is difficult to start.
Greetings!
When you use a PostgreSQL database, you can make use of the .distinct(..) method [Django-doc] of the queryset where you add fields that determine on what these should be distinct.
So you can obtain the latest sensors in Django with:
SensorModel.objects.order_by('sensor', '-timestamp').distinct('sensor')
We thus order by sensor (which is required for a .distinct(..)), and then in case of a tie (so two times the same sensor), we order on the timestamp in descending order, hence we pick the latest SensorModel object for that sensor.
I would like to do something like:
App.Model.find({unique_attribute_a: 'foo'}).objectAt(0).get('attribute_b')`
basically first finding a model by its unique attribute that is NOT its ID, then getting another attribute of that model. (objectAt(0) is used because find by attribute returns a RecordArray.)
The problem is App.Model.find({unique_attribute_a: 'foo'}).objectAt(0) is always undefined. I don't know why.
Please see the problem in the jsbin.
It looks like you want to use a filter rather than a find (or in this case a findQuery). Example here: http://jsbin.com/iwiruw/438
App.Model.find({ unique_attribute_a: 'foo' }) converts the query to an ajax query string:
/model?unique_attribute_a=foo
Ember data expects your server to return a filtered response. Ember Data then loads this response into an ImmutableArray and makes no assumption about what you were trying to find, it just knows the server returned something that matched your query and groups that result into a non-changable array (you can still modify the record, just not the array).
App.Model.filtler on the other hand just filters the local store based on your filter function. It does have one "magical" side affect where it will do App.Model.find behind the scenes if there are no models in the store although I am not sure if this is intended.
Typically I avoid filters as it can have some performance issues with large data sets and ember data. A filter must materialize every record which can be slow if you have thousands of records
Someone on irc gave me this answer. Then I modified it to make it work completely. Basically I should have used filtered.
App.Office.filter( function(e){return e.get('unique_attribute_a') == 'foo'}).objectAt(0)
Then I can get the attribute like:
App.Office.filter( function(e){return e.get('unique_attribute_a') == 'foo'}).objectAt(0).get('attribute_b')
See the code in jsbin.
Does anyone know WHY filter works but find doesn't? They both return RecordArrays.
I currently have a .NET method that looks like this - GetUsers(Filter filter) and this is invoked from the client by sending a SOAP request. As you can probably guess, it takes a bunch of filters and returns a list of users that match those filters. The filters aren't too complicated, they're basically just a set of from date, to date, age, sex etc. and the set of filters I have at any point is static.
I was wondering what the RESTful way of doing this was. I'm guessing I'll have a Users resource. Will it be something like GET /Users?fromDate=11-1-2011&toDate=11-2-2011&age=&sex=M ? Is there a way to pass it a Filter without having to convert it into individual attributes?
I'm consuming this service from a mobile client, so I think the overhead of an extra request that actually creates a filter: POST filters is bad UX. Even if we do this, what does POST filters even mean? Is that supposed to create a filter record in the database? How would the server keep track of the filter that was just created if my sequence of requests is as follows?
POST /filters -- returns a filter
{
"from-date" : "11-1-2011",
"to-date" : "11-2-2011",
"age" : "",
"sex" : "M"
}
GET /Users?filter=filter_id
Apologies if the request came off as being a little confused. I am.
Thanks,
Teja
We are doing it just like you had it
GET /Users?fromDate=11-1-2011&toDate=11-2-2011&age=&sex=M
We have 9 querystring values.
I don't see any problem with that
The way I handle it is I do a POST with the body containing the parameters and then I return a redirect to a GET. What the GET URL looks like is completely up to the server. If you want to convert the filter into separate query params you can, or if you want to persist a filter and then add a query param that points to the saved filter that's ok too. The advantage is that you can change your mind at any time and the client doesn't care.
Also, because you are doing a GET you can take advantage of caching which should more than make up for doing the extra retquest.
I'm trying to make a Django order system that requires 2 forms. The first form, lets users choose some some quantities and basic contact info some. Then, using the quantities of each item they ordered I generate a 2nd form which allows them to choose some options for each item. This system is specifically for event tickets. Here are the 2 stages:
1) Get the order info such as name, address, phone of the person placing the order. Also find out how many people are coming to each of the possible events.
2) Based on the number of people per event, get their name and e-mail address.
I already have both forms created. I am just getting tripped up in the views. When they submit form 1, I need to take that info and save some of it and then send them to form 2. At form 2, they will fill out the rest of the info and finish processing.
How would you set up the views in such as case? I essentially nee-d to call on view form another and pass data between. I tried using kwargs, but I have trouble processing the second form.
Without seeing your models, it's hard to give an exact solution, but one approach is to have two separate views, one for each form.
Once you've processed the first form, you're most likely going to have an instance of some object that you created from the first form. It sounds like you just need to pass the id of that object to your next view where you could then get that object and do whatever association you need.
Also, it sounds like you might need to be collecting data from several instances of a form...
(2) Based on the number of people per event, get their name and e-mail
address.)
You'll want to use a formset for that.