How to Connect Firebase Users to their Data - 3 Methods

Key Takeaways

in this episode I'm going to talk about ways to associate Firebase users with data in the real-time database I'll go over three different methods and when to use them and also talk about ways to keep them secure on the back end but before we get into that it's important to go over a couple nosql database design best practices if you come from a SQL background you're used to designing a database that is completely centered around relationships in no SQL we care less about relationships and more about about the efficiency of the actual query that we're making consider a database design that has everything nested under the user ID if you wanted to Loop over just the users and display their username you'd also have to load all the nested data further down the tree which would become very inefficient if you have a lot of Records a better way to handle this is to keep the data shallow so you only query for the actual data you need now we can start building some user relationships with Firebase and angular 4 the first method work works by nesting a user's items under their own user ID this is ideal when you're showing data that's organized by user for example a Twitter feed here we have an item service and we're going to import both the angular fire database and the angular fire off module then we create an item class which represents our data at this point with just one body string attribute this class will be returned to us as an angular fire list Observer when we inject the service we want to subscribe to the angular fire off State and we'll set the user ID return from that off state to the user ID on the service this allows us to make queries based on the currently logged in users ID now that we have the user ID we can hit the database for the list that is nested under that user ID if it's undefined we just return null it's defined we interpolate it into the path to the database if we want to create a new item it's as simple as pushing another item object onto this list observable back in the app we can see that when we create a new item it's nested under that user's user ID as expected if we log out and log in with a different user we shouldn't see any items in the feed which we don't and if we create a new item with this user their data is nested under their user ID essentially separ ating the data by user this works great on the front end but we also need to secure the backend data with a Firebase database rule in this example we match the user ID that the data is nested under with the actual o ID and Firebase if it's a match then we allow the right operation to take place a second way to associate users with items is to save the user ID as an attribute on the item itself this approach is useful when you need the association but you're not quering by the user for example comments on a blog post or something similar we can make this work by modifying three lines of code first we add a user ID to the item class then we set that user ID on the item when it's created then we remove the user ID from the database path because we're no longer nesting under the user ID back in the app we create a new item and we can see that user ID is on the item itself then if we create another item with a different user we should have a different user ID on that item but still both items are coming up in the feed now in Firebase we can see the user ID attribute is on each item to secure the back end we see if the existing data in the database has a matching user ID and we also allow the right to occur if it's null because that means the user is creating a new item the third scenario is when you have items that can be associated with multiple users in this case we create a collection of members that are nested under the item ID and the key for each member is that user's user ID back in the service we'll create a new function to join an item passing it the items key as an argument the data will be the user ID for the key set to true we return the current members as an object observable then update that observable with the new data to leave an item we follow the same basic approach we query for an object observable with the current user ID and if it exists we remove it back in the app we create a new item that defaults to no members and then we can click the join button which will add that user ID to the list of members when we log in with a different user we should see that they can also add their user ID to this item going into Firebase we can see that the members collection on this item gets updated with the key after each button is [Music] clicked that's it for this episode if you found the video helpful please like And subscribe and if you want to support the channel consider becoming a pro subscriber at angular firebase.com for just a few bucks a month you'll get access to exclusive content as well as free oneon-one project Consulting thanks for watching and I'll see you next [Music] time