What would be the best way to store daily health related data (height, weight, calories burned, hours of sleep) in a Parse (MongoDB) database? The user will update their health data up to 10-15 times a day and I am unsure how to track their data in real time without having to create a new record every time they update only a certain piece of information. Currently I have a User class and a HealthProfile class, which contains basic information about height, weight, etc.
I could collect the data over the course of the day and then save it in the database at night however this will not work for database driven charts I want to display.
Data Interaction will be as follows: throughout the day a user inputs how much exercise they did, food they ate, etc. and the app will display a line/bar chart showing their progress/calories burned (or other health figures) for the day, week, and month. It will also include things like blood pressure and other measurements and I want to be able to store all of these things for a user and allow them to view their history, as well as input new data, at any time. It is a similar concept to how Apple's Health app works.
I will need to make sure the user's data is always persisted in a database so if they login on their phone or the website, their data is always up to date, so writes to the database will need to be upon user input and reads will take place any time the user view a chart or figure.
You really need to work out how you want to interact with the data. That will determine the best way to store it.
Once you have a clear picture of the different ways you want to read/write/use the data come back and ask clear questions to get help... currently it isn't clear what sort of help you want.
Related
I have simple game on Google Play and Apple App Store that I have created in Unity. Now I am thinking about creating a global high score, so if you are in top 10 for example you can enter a made up user name.
The thing is I do not want the users to sign in since I want the game to be easy to access. One user can also enter a new username each time a record is beaten. So you can for example have the first three positions.
In principle, the app should read the high score from database and one should be able to write to it with {userID, new_score}, but no data is connected to any particular user. I am used to work with Firebase, what would be the easiest way to achieve this?
Thanks,
Erik
Well, the fact that you don't have data connected to any particular user do not means that you can't store the highscores. Cause one user can beat himself.
So if your database (I don't know if it's realtime or firestore) knows which are the top scores, when a user (indpendently of his ID) beats the score threshold, you can give him the option to put a name on that highscore, and update your database with this new score.
I will also recommend to bind users with data, his highscore or the name it's using to register the highscore, but you can achieve the same result without it.
You could try having a read and create only set of records, where write requires a valid anonymous auth key. I haven't tried that setup with Anonymous only auth before though.
Otherwise you could also try setting up a cloud function to validate and write the high score records.
I'm trying to download 1 minute historical stock prices from Yahoo Finance, both for the current day and the previous ones.
Yahoo (just like Google) supports up to 15 days worth of data, using the following API query:
http://chartapi.finance.yahoo.com/instrument/1.0/AAPL/chartdata;type=quote;range=1d/csv
The thing is that data keeps on changing even when the markets are closed! Try refreshing every minute or so and some minute bars change, even from the beginning of the session.
Another interesting thing is that all of these queries return slightly different data for the same bars:
http://chartapi.finance.yahoo.com/instrument/2.0/AAPL/chartdata;type=quote;range=1d/csv
Replace the bold number with 100000 and it will still work but return slightly different data.
Does anyone understand this?
Is there a modern YQL query that can fetch historical minute data instead of this API?
Thanks!
Historical minute data is not as easily accessible as we all would like. I have found that the most affordable way to gather Intraday Stock Price data is to develop automated scripts that log price information for whenever the markets are open.
Similar to the Yahoo data URL that you shared, Bloomberg maintains 1-Day Intraday Price information in JSON format like this : https://www.bloomberg.com/markets/api/bulk-time-series/price/AAPL%3AUS?timeFrame=1_DAY
The URL convention appears easy to input on your own once you have a list of Ticker Symbols and an understanding of the consistent syntax.
To arrive at that URL initially though, without having any idea for guessing / reverse-engineering it, I simply went here https://www.bloomberg.com/quote/AAPL:US and used Developer Tools on my browser and tracked a background GET request which led me to that URL. I wouldn't be surprised if you could employ similar methods on other Price Data-related websites.
You can also write scripts to track price data as fast as your internet goes. One python package that I find pretty handy and is ystockquote
You can have it request price data every couple of seconds and log that into a daily time series database.
Yes there is other APIs.
I don't know if it can still help but if you need intraday data, there is a API on rapidapi called (Quotient) which allows to pull intraday (at 1-min level), EOD market (FX, Crypto, Stocks (US, CANADIAN, UK, AUSTRALIA, EUROPE), ETFs and Futures. It also provides earnings, dividends, splits and a lot others informations.
I have an iOS app that presents content in a tableView. I've added a 'like/dislike' feature that interacts with my database (I use Parse.com). Every time someone likes/dislikes a piece of content, the specifics are sent to the Parse database. For each piece of content, I'd like to calculate and display the percentage of 'likes' over 'likes' + 'dislikes'. This is pretty simple math, but I can't wrap my head around the best way of designing my database table and the most efficient way to calculate the 'liked' percentage for each piece of content before the tableView physically appears.
As it is, I already have a loop in my tableView's viewDidLoad which compares the content from another database table to the 'like/dislike' table to restore the 'like/dislike' button state of the user (if they already liked/disliked a piece of content).
At first, I thought of creating an array in the initial viewDidLoadloop. However, using the whereKey: equalTo: type of query for each piece content to simply find the amount of likes/dislikes takes forever. As predicted, it is very slow in cellForRowAtIndexPath as well.
Worst case, I can make these calculations server-side and just pull the 'liked' percentage. However, I'd like to implement this in the app somehow. I'm a complete beginner, so I may be going about this all wrong.
Here is the basis of my database table:
Edit: I've managed to build a server-side program that calculates the percentage of users that 'like' pieces of content. My app pulls this percentage from the database at runtime. To make the percentage change more responsive when the user 'likes' something, I locally calculate an updated percentage. The problem here is when the user exits the app and reopens, the data reloads. If the server-side program had not run recently, the app will display an old 'liked' percentage (the most up to date % would not be calculated yet). The two solutions I see to fix this are:
Run the server-side program every 1-3 min
Post more data to the database when someone likes content (this would involve additional database queries for every single 'like').
I think both of these options are way too expensive for what I'm trying to accomplish.
I'd suggest leaving the calculations to the server side, and responding with the information to utilize in the app. This will save you from processing and parsing the incoming results.
You have greater processing power on a Server than on a device.
Q1) I am designing a iPhone app and want to know on what basis I should take the decision of caching data.
Q2) I have a huge data set which can change frequently. On my app I am showing the data under different categories and is planning to fetch the data from server when a particular category is tapped. This will reduce the data transfer. Also, this data can change frequently but I can store it for let say 30 minutes. What strategy should I take here? Should I store in core data or no caching all together and for each repetitive taps should hit the server?
Please suggest.
What does "hit" mean in this context? Asking the server whether your data is fresh or simply refetching it?
I would suggest that you cache a few MB or so, that you assume that data stays fresh for at least thirty seconds or so (depends on your scenario). If you want the application to feel very fluent, download everything that can be reached with two taps (or so) or less if it isn't yet cached after each tap (as long as that isn't too much data).
You might also want to include a less-data-mode for users who have a traffic-based-costs internet access.
It totally depends upon the frequency of new data. You can cache the data that's to be displayed at the application launch in all your tabs and then let the updated data flow when user makes request for new data.
Does anyone know how sites that have a real-time feed of a lot of data work? I am referring to something like a stock site, where they can tell you in real time (well, 20 minute delay mostly, but still real-time - 20 minutes as I understand it).
They have thousands of data pieces delivered to them every second, I would imagine: MSFT 25.00 +.23 VOL 12000 ???? for each stock that had a change during some interval.
So, is there just a constant feed of small pushes going on? Or do you think a site will pull from the place that has the real data and say "give me all changes since 12:23:45 CST to now" type query?
I ask this because at work we might have a situation where we need to have at our application's fingertips real time information like this, and it won't make sense to hit our third party provider over and over and over again every second...
Generally there is a server/client protocol defined between the 2 parties. In the company I work for the connection is maintained at all times.
Here is info on real time data feeds to go with your stock example
NYSE,NASDAQ
It is common for data providers to also have FTP sites with (delayed) batched data. One that comes to mind is the NWS EMWIN
Sites like Twitter feed data to certain approved sites in real-time via XMPP (Wiki link).
In the broadest terms, a push model is going to be the best way of achieving "real time" transfer, particularly if you're talking about a large amount of data.
However you do always have a problem when using a purely push model of how to recover from missed data.
Depending on the nature of your data that may not be a problem (thinking of video delivery as an analogue, where the amount of data is huge but there is sufficient redundancy for it to recover from missing data). And if you have any control over the data you may be able to build some redundancy in. For example, on every change event you can provide absolute values rather than changes, or previous value and new value.
I've done this making an attempt to retrieve the stock quote from the source, and falling back to a timestamped on-disk cache of the quote when the main source fails or times out.