I have a database of posts in firebase, and each has a timestamp and a rating.
i know how to order by time OR by rating, but would it be possible to order by rating, then limit by time. ie. show highest rated posts over the last week?
ie.
Ref.queryOrderedByChild("rating").observeSingleEventOfType(.Value, withBlock: {...}
would order by rating, but how would i then limit the query by time, and not rating?
Unfortunately, Firebase does not support cross referencing nor server-side logic, so you'll probably have to query by the more specific value, pull the data down, then sort the rest client side.
Alternatively, you could also try to get creative with GeoFire (firebase's cross referencing solution for latitude/longitude location querying), though that'll the hackiest solution ever...
Related
I export my bank transactions to a PDF, that I then paste to a google spreadsheet.
Problem is: I may need to sort the transactions on my spreadsheet, and after reordering by date the amounts and balance may "shift" when there are several transactions on the same day:
It's not a big problem to me, but my accountant is all lost.
I would like to find a way to identify the orders of the transactions of a same date, by comparing the amounts/balance to the final balance of the previous date.
I managed to create a formula using a MATCH that would identify the first transaction of a specific date, but if I were to make it work for 10-20 potential transactions within a same date, it would get stupidly long and complex. I may eventually do that, but before i'd like to know if there is an easier solution.
I can add as many columns as I want, and I don't mind using scripts.
What I cannot do is create a column that would recalculate the balance according to the order the transactions are in. That would be the easiest solution, but if my accountant were to compare with what is on the real bank account, he would find discrepancies and be just as lost.
Thank you!
As #gries said:
Since your PDF contains the transactions already ordered the way you want you can assign to each of them an incremental ID.
In such a way, you will be able to restore the initial order ordering by the transaction ID instead of using the date that could be repeated.
I'm producing a project with Firebase Realtime Database.
I have to post pictures with timestamp, latitude and longitude, and search for pictures in a radios from my position, ordered by timestamp and with the value of the timestamp 1 days from now.
Is Firebase Realtime Database + Geofire right for me?
I cannot figure out how to make queries.
Thank you!
The Realtime Database only supports one dimensional queries. So, if you did want to use
the RTDB, you'd need a two-stage query.
geoquery all the pictures in your given center/radius.
for each of these pictures, query all the data for that picture.
Once the data arrives for all the pictures, filter/sort client side.
RTDB structure would be something like:
pictures/{pic_id}: {
timestamp:,
name:
[,...]
},
geofire_pictures/{pic_id}: <geofire data>
With that said, I think RTDB would be a fine choice if you expect your
result set sizes to be managable. If you need to scale, I would suggest waiting for Firestore's geoquery functionality.
I am working on an application that retrieves the posts from firebase. The problem is I want to retrieve the first 20 posts and show in a table. When a user clicks the next button, it will retrieve the next 20 posts and show and so on.
I know firebase provides the following methods
queryLimitedToFirst
queryLimitedToLast
queryStartingAtValue
queryEndingAtValue
queryEqualToValue
But how do I use them in conjunction to retrieve the desired results like I want?
Here is the structure of the data I have:
You should order query by some property (I usually use timestamp). This organises your orders from latest to oldest. When you have them ordered you should limit them:
queryOrdered(byChild: "timestamp").queryLimited(toLast: UInt(limit))
As you can see we can limit results to whatever number we like. You can use this to read your posts each time for 20 results more.
So the first time you call it with a limit of 20, next time with a limit of 40, etc. Keep in mind that this will return posts that were already returned in the previous call.
Instead you could combine it with queryStartingAtValue and use your last post tiemstamp - this will "skip" your previous results and return only 20 posts you need.
This is just an idea but I think it should work like expected.
Due to the PowerShell methods of getting mailbox statistics from Office365 taking about 2 seconds per mailbox, I am working on getting the data from Office 365 Reporting web service, which takes only a few seconds for each 2000 mailboxes.
The problem I'm running into is that the stats are updated periodically and some historical data is kept, so there are numerous records for each user. I only want to get the latest record for each user, but I haven't been able to find a way to do that. The closest I've come is to use $filter=Date ge DateTime'2016-03-10T00:00:00' where the date is concatenated to a couple of days ago. Theoretically, if I sort by Date desc I should get the latest records first, and if there is a user that has a record for 3/10 and 3/11, the 3/11 record would get pulled first, which would work for me. But regardless of how I do the sort it seems to come back with the older records first.
Ideally, I would like to be able to set criteria so that it only returns the latest record for each mailbox, but I can't seem to figure out or find how to do that. The closest I've been able to come is to just start running queries filtered on specific dates, walking the date back a day on each query.
If I can get the latest records to be returned first, I would be able to work with that because I can just discard a record if I've already received a later one.
https://reports.office365.com/ecp/reportingwebservice/reporting.svc/MailboxUsageDetail/
?DelegatedOrg=nnn.onmicrosoft.com&$select=Date,WindowsLiveID,CurrentMailboxSize
&$filter=Date ge DateTime'2016-03-08T00:00:00'&$orderby=Date desc
So the questions are:
Is there a way to specify criteria so that only the latest record for each user is returned?
Is there a way to get it to order by Date descending--what am I doing wrong with the $orderby?
Thanks!
You can use $top=1 to get latest record by applying $orderby on date (desc). $filter and $skip may not require in this case.
https://reports.office365.com/ecp/reportingwebservice/reporting.svc/MailboxUsageDetail/?DelegatedOrg=nnn.onmicrosoft.com&$select=Date,WindowsLiveID,CurrentMailboxSize&$orderby=Date desc&$top=1
Your query looks fine, here is an another example from Odata sample service to get employee detail with most recent birth date.
http://services.odata.org/V4/Northwind/Northwind.svc/Employees?$select=EmployeeID,FirstName,LastName,BirthDate&$orderby=BirthDate%20desc&$top=1
I'm looking to build an analytics dashboard for my data in a rails application.
Let's say I have a list of request types "Fizz", "Buzz", "Bang", "Bar".
I want to display a count for each day based on type.
How should I do this?
Here is what I plan on doing:
Add get_bazz_by_day, get_fizz_by_day, etc to the appropriate models.
In each model get all records of type Fizz, then create an array that stores date and count.
format in view so a JS library can format it into a pretty graph.
Does this sound reasonable?
Depending on number of records, your dashboard can soon get performance problems.
Step 1 is misleading. Don't get the data for each day individually, try to get them all at once.
In Step 2 you can have the database do the the aggregation over days, with the group method.
See http://guides.rubyonrails.org/active_record_querying.html#group
Fizz.select("date(created_at) as fizzed_day, count(*) as day_count").
group("date(created_at)")
In Step 3 you need to take care that days without any fizzbuzz are still displayed, as they are not returned in the query.