🕰️ Chapters
- Demoing Why You'd Use A Transaction
- What Is A Database Transaction?
- Creating A Database Transaction
- Binding Our Transaction To Our Database Operations
- Demoing A Transaction In Action
- Displaying An Error On Transaction Rollback
Saving All Or Nothing with Database Transactions
In this lesson, we'll learn about database transactions and how we can use them to batch commit or rollback updates, safeguarding against partial updates due to errors.
- Author
- Tom Gobich
- Published
- May 29
- Duration
- 5m 15s
Developer, dog lover, and burrito eater. Currently teaching AdonisJS, a fully featured NodeJS framework, and running Adocasts where I post new lessons weekly. Professionally, I work with JavaScript, .Net C#, and SQL Server.
Adocasts
Burlington, KY
Transcript
Saving All Or Nothing with Database Transactions
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(upbeat music)
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So for our profiles update here,
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let's say that we only ever want the profile
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and description to update whenever both of these saves
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actually happen successfully.
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For example, at present,
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if we were to invalidate our profiles update
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by doing something like profile.userid
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and setting that to some user
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that does not exist inside of our database,
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this save call will then result in an error
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because it won't be able to find a user
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thanks to our foreign key constraint
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with whatever this ID is here.
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If we give that a save, jump back into our browser
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and let's switch our John Doe edit to John Doe edit two
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and let's switch our biography to John Doe edit two
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to match the name and hit update here.
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We do indeed get our error as expected
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because of our foreign key constraint,
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but now if we go back into our profile edit page,
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so if we go back and refresh
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just to make sure that we have the latest data,
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you'll see that things actually updated
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despite us running into an error,
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meaning that not all of our operations
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completed successfully.
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And that's where transactions come into play.
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A transaction is essentially going to keep track
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of the changes that we're making
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and provide us a way to either commit them fully
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to the database long-term or roll them back to undo them.
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So first, what we're gonna wanna do
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is from everything up through our profile
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down through our save changes,
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let's wrap this inside of a try catch.
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Oh, so try catch just like so
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and paste our profile query
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along with our saves inside of there.
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Then let's go ahead and create a transaction.
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So do const TRX, short for transaction
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equals await import our DB
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from AdonisJS Lucid Services DB
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and call dot transaction.
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This will return back a new instance
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of a transaction for us,
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which contains a commit and rollback method
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doing exactly what we described earlier.
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So if everything completed successfully
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and we run through all of our calls that we have here,
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we'll want to await TRX
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and commit those changes to our database.
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If we run into an error at any point in time,
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we'll want to await TRX dot roll back those changes
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to undo them rather than committing.
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The next thing that we need to do
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is actually bind this transaction to these calls.
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And since all of our calls here
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actually go through our user,
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we'll want to bind that directly to our user.
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So we can do off user exclamation point to assert it.
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And there's a method called use transaction
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that we can call and pass in the transaction
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that we want our user model to use.
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And this cascades through
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as we query things with our relationships.
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So for example, inside of our profile service
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with our find call, we're using our user model's relationship
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to actually query out the profile,
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meaning that the returned profile
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will then be attached to that same transaction as well.
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If you don't have that system,
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what you could always do is just use transaction
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on the profile, just the same as we are with our user here.
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Since we do have that cascading through our relationship,
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though, we don't need to worry about that
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in this particular use case.
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You can also pass transactions
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through to other calls as well.
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So for example, if we were doing a wait,
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I'm going to go ahead and just import our profile model here
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temporarily and call create.
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We'll pass in our data.
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The second argument is where we can pass in a client,
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which is a transaction client.
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So we could create with a transaction just like so.
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And a lot of these static methods work the exact same way
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where you have query options as the second argument
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where you can pass in a client for your actual transaction.
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Okay, let's go back a couple of steps
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and let's give this a run.
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So first let's go ahead and put our error back.
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So profile.userid equals some ID
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that definitely doesn't exist inside of our database.
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Let's go and jump back into our browser
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and let's try to switch this to a three.
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Let's update our profile.
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And you'll see that we ran into an error,
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but since we're now catching that error,
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we just get returned back here,
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which is what we're specifying to do
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at the end of our handler.
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So that's expected behavior.
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But in addition to that,
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you also see that our three change did not persist
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in either of these two contexts.
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Additionally, it looks like Firefox was holding on
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to the edit two value from our biography there
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from our initial error.
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Cool, let's do a hard refresh
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just to make sure it's not holding on to anything else.
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There we go, okay, cool.
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So let's try that once more.
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Three there, three there, update.
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And you'll see it goes right back
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to how it was prior to that change,
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because neither of those two changes
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are actually saving into the database now
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because our transaction is being rolled back
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due to this foreign key constraint error.
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If we remove that error, jump back into our browser,
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and now we try to switch these to three,
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give that an update,
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you'll see everything goes through A-okay.
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Give this a refresh.
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Everything still works A-okay.
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It'd probably be good to go ahead
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and display some form of an error
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whenever this does actually happen.
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So let's go ahead and grab our session,
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scroll back down, and we can do session.lash,
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and we can flash something into our errors bag
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and call that maybe something like form
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with a message of something went wrong,
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or whatever you'd like there for the message.
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Give that a save,
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and then we'll jump back into our edit page.
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And actually, let's jump back into our login page
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and grab this error right here.
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Jump back into our edit page now,
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paste it in above our inputs.
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And instead of looking for E invalid credentials,
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we're just gonna be looking for a form error.
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Our message will remain the same.
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Give that a save.
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And actually, before we test that out,
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we do need to add our error back in.
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So profile.userID equals some non-existent ID there.
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And now let's test it out.
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So switch those to four, update, and there we go.
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So now we get something went wrong
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whenever something actually goes wrong,
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and our transaction gets rolled back.
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Introduction
-
Fundamentals
-
2.0Routes and How To Create Them5m 24s
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2.1Rendering a View for a Route6m 30s
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2.2Linking Between Routes7m 52s
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2.3Loading A Movie Using Route Parameters9m 18s
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2.4Validating Route Parameters6m 7s
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2.5Vite and Our Assets6m 39s
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2.6Setting Up Tailwind CSS7m 5s
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2.7Reading and Supporting Markdown Content4m 32s
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2.8Listing Movies from their Markdown Files8m 51s
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2.9Extracting Reusable Code with Services7m 4s
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2.10Cleaning Up Routes with Controllers4m 52s
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2.11Defining A Structure for our Movie using Models9m 38s
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2.12Singleton Services and the Idea of Caching6m 11s
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2.13Environment Variables and their Validation4m 16s
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2.14Improved Caching with Redis10m 44s
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2.15Deleting Items and Flushing our Redis Cache6m 46s
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2.16Quick Start Apps with Custom Starter Kits6m 28s
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2.17Easy Imports with NodeJS Subpath Imports8m 40s
-
-
Building Views with EdgeJS
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3.0EdgeJS Templating Basics8m 49s
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3.1HTML Attribute and Class Utilities6m 9s
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3.2Making A Reusable Movie Card Component10m 24s
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3.3Component Tags, State, and Props4m 53s
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3.4Use Slots To Make A Button Component6m 56s
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3.5Extracting A Layout Component5m 13s
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3.6State vs Share Data Flow2m 59s
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3.7Share vs Global Data Flow6m 8s
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3.8Form Basics and CSRF Protection6m 13s
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3.9HTTP Method Spoofing HTML Forms3m 3s
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3.10Easy SVG Icons with Edge Iconify7m 57s
-
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Database and Lucid ORM Basics
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4.0Configuring Lucid and our Database Connection4m 3s
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4.1Understanding our Database Schema9m 35s
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4.2Introducing and Defining Database Migrations18m 35s
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4.3The Flow of Migrations8m 28s
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4.4Introducing Lucid Models5m 43s
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4.5Defining Our Models6m 49s
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4.6The Basics of CRUD11m 56s
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4.7Defining Required Data with Seeders11m 11s
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4.8Stubbing Fake Data with Model Factories13m 48s
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4.9Querying Our Movies with the Query Builder15m 30s
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4.10Unmapped and Computed Model Properties3m 24s
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4.11Altering Tables with Migrations7m 6s
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4.12Adding A Profile Model, Migration, Factory, and Controller2m 57s
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4.13SQL Parameters and Injection Protection9m 19s
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4.14Reusable Query Statements with Model Query Scopes8m 11s
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4.15Tapping into Model Factory States9m 15s
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4.16Querying Recently Released and Coming Soon Movies4m 59s
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4.17Generating A Unique Movie Slug With Model Hooks7m 59s
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Lucid ORM Relationships
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5.0Defining One to One Relationships Within Lucid Models5m 49s
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5.1Model Factory Relationships2m 54s
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5.2Querying Relationships and Eager Vs Lazy Loading5m 17s
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5.3Cascading and Deleting Model Relationships5m 16s
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5.4Defining One to Many Relationships with Lucid Models6m 56s
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5.5Seeding Movies with One to Many Model Factory Relationships5m 24s
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5.6Listing A Director's Movies with Relationship Existence Queries8m 41s
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5.7Listing and Counting a Writer's Movies8m 41s
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5.8Using Eager and Lazy Loading to Load A Movie's Writer and Director5m 18s
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5.9Defining Many-To-Many Relationships and Pivot Columns9m 48s
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5.10Many-To-Many Model Factory Relationships4m 50s
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5.11A Deep Dive Into Relationship CRUD with Models18m 5s
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5.12How To Create Factory Relationships from a Pool of Data13m 55s
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5.13How To Query, Sort, and Filter by Pivot Table Data9m 47s
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Working With Forms
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6.0Accepting Form Data12m 15s
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6.1Validating Form Data with VineJS9m 29s
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6.2Displaying Validation Errors and Validating from our Request7m 16s
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6.3Reusing Old Form Values After A Validation Error2m 3s
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6.4Creating An EdgeJS Form Input Component5m 28s
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6.5Creating A Login Form and Validator5m 1s
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6.6How To Create A Custom VineJS Validation Rule9m 7s
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Authentication & Middleware
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7.0The Flow of Middleware7m 49s
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7.1Authenticating A Newly Registered User4m 14s
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7.2Checking For and Populating an Authenticated User2m 10s
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7.3Logging Out An Authenticated User2m 24s
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7.4Logging In An Existing User6m 54s
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7.5Remembering A User's Authenticated Session6m 55s
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7.6Protecting Routes with Auth, Guest, and Admin Middleware5m 36s
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Filtering and Paginating Queries
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8.0Creating A Movie List Page3m 43s
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8.1Filtering A Query By Pattern Likeness7m 9s
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8.2Filtering Our List by Movie Status5m 47s
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8.3How To Apply A Dynamic Sort Filter To Your Query7m 12s
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8.4Joining SQL Tables To Order By A Related Column4m 49s
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8.5Validating Query String Filter Values7m 24s
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8.6How To Paginate Filtered Query Results9m 15s
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8.7Pagination First, Last, Next, and Previous Buttons4m 3s
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User Watchlist
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9.0An Alternative Approach to Many-To-Many Relationships4m 56s
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9.1Toggling A Movie in an Authenticated User's Watchlist9m 56s
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9.2Listing and Filtering User Watchlist Items7m 31s
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9.3Allowing Users To Toggle A Movie As Watched4m 44s
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9.4Filtering By User's Watched Status6m 7s
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9.5Defining A Composite Unique Constraint4m 47s
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9.6Persist Filters Easily with Lucid's Query String Method3m 58s
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User Profiles
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10.0How to Create and Fix Missing User Profiles in Your Application7m 37s
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10.1Using Dependency Injection to Update A User's Profile9m 46s
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10.2Saving All Or Nothing with Database Transactions5m 15s
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10.3Uploading and Displaying User Avatars15m 29s
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10.4Displaying A User's Profile6m 1s
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10.5Filtering, Preloading, and Sorting By Relationship7m 6s
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Admin Panel
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11.0Creating An Admin Layout7m 14s
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11.1Counting Stats for our Admin Dashboard5m 43s
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11.2Paginated Admin Movie Table13m 2s
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11.3Allowing Admins to Create Movies16m 39s
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11.4Allowing Admins to Update Movies and Clear Values13m 27s
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11.5How To Use One Form to Create or Edit Movies5m 32s
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Uploading Movie Cover Images in our Create or Edit Form10m 29s
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Using A Wildcard Route Param to Download Storage Images7m 57s
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Posting Objects, Arrays, and an Array of Objects in HTML Forms26m 26s
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Managed Transactions and Syncing Movie Cast Members15m 55s
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Allowing Admins to Delete Movies and their Relationships7m 42s
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Thank You for Watching!0m 31s
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