--- title: Translate Sinatra to Rails slug: translate-sinatra-to-rails published_at: 2021-01-01 15:00:08 +0000 updated_at: 2026-03-04 20:14:37 +0000 summary: description: The code for this episode is available here: https://github.com/cjavdev/sinatra-to-rails-translation #rails #rubyonrails tags: [Sinatra to rails translation, Sinatra to rails, Sinatra, Ruby on Rails, Rails, Ruby] views: 460 author: CJ Avilla url: https://www.cjav.dev/videos/translate-sinatra-to-rails youtube_url: https://www.youtube.com/watch?v=f5GwoBk1_F4 youtube_id: f5GwoBk1_F4 embed_url: https://www.youtube.com/embed/f5GwoBk1_F4 thumbnail_url: https://i.ytimg.com/vi/f5GwoBk1_F4/hqdefault.jpg type: video --- # Translate Sinatra to Rails *Published: January 01, 2021* *Views: 460* ## Watch [Watch on YouTube](https://www.youtube.com/watch?v=f5GwoBk1_F4) [![Translate Sinatra to Rails](https://i.ytimg.com/vi/f5GwoBk1_F4/hqdefault.jpg)](https://www.youtube.com/watch?v=f5GwoBk1_F4) ## Description The code for this episode is available here: https://github.com/cjavdev/sinatra-to-rails-translation #rails #rubyonrails ## Transcript all right so i got a question on twitter here that says um you know for beginners there's a knowledge gap between the stripped down sinatra and the conveniences or the conventions offered by ruby on rails and so what i wanted to do was quickly go through an example where we look at a sinatra app and talk about how that would work in rails so i'm going to use one of the stripe samples stripe samples create uh check out one-time payments this is a really simple stripe sample and the reason why i wanted to use it is that um it will show get request post requests and web hooks and um kind of it should it should help folks kind of close that gap if you're looking at a sinatra example and want to know how things fit together so this is the the sinatra example sinatra is like really slimmed down you basically just have in some cases or in many cases you'll just have a single file called server.rb in like most of the code if not all of the code will just live in that one file this file is 114 lines long and the way that it works is you define routes by calling methods and the methods are like get post put delete etc etc and when you define them you pass in the path or like the string path that it should match on so in this case we're saying um a get request to the root route should execute this block this ruby block and whatever the return value is or if we're calling send file um yeah no no like whatever the return value is of the block so the last the implicit return value in ruby is the last line that's executed um so that's the the content that's going to be returned to the client that is making the request so here we have a get request to slash and it says return some html in this case it's finding index.html in a in the local directory so that that lives here in client under index.html so it's just like reading in that file and sending that back to the client that's what this get route is doing and then git config is just sending back some some json here so this is how you would render back json in sinatra so let's uh so as we're working through this let's actually implement this same server uh in an in a rails application um let's see so so this is check out one time payments that's our stripe sample and i'm going to say rails new checkout translation um check out rails translation and we'll say no tests um skip turbo links skip listen database is postgres uh in the stripe samples and many times when you look at sinatra examples they're not going to have a database or maybe they will maybe they won't but in in the case of stripe samples we don't usually have a database but i think rails maybe rails would just use sqlite if we didn't give it anything so we are installing a brand new rails app all right so we have successfully installed rails uh okay so the first thing that you'll notice in rails is that it comes with way more uh files okay so this is a just a brand new vanilla rails app right and it comes with all these directories and files and so the very first thing we want to do is like if we just go to the very top here require stripe so in sinatra we just require the gem at the top you may have a gem file which specifies the gems that you are like managing or whatever in rails we're going to have a gem file also so let's go make sure that we have stripe installed in our gem file for rails so in on the rails side i'm going to open up gemfile you'll notice it comes with a whole bunch of gems to start with but at the very bottom we can just add gem stripe and then here we have we also have our spec and rest client oh actually sorry this is the gem file that we care about dot end sinatra and stripe and that's it so um i'm not gonna install dot n so dot end is a gem for managing environment variables rails comes with a built-in credentials or secret management thing so we're going to use that when we work with rails so we only really need to install the stripe gem so we've done that after you change the gem file you have to run bundle install so that it pulls down those gems that are the libraries and installs them for you okay so now that we have bundle installed let's keep going so we've required sinatra required.n and then we call dot end dot load this dot n thing we cover this we cover dot end and how we use in uh dot end environment variables in some episodes that are over on the stripe developers channel so if you want to go head over there and check that out that's how those or that that might be helpful in understanding like this gem and what this command or what this method does on.end all right then the next thing we're doing here is we're trying to check we're doing like a simple environment variable check so when we call dot end dot load it should load up the environment variables that are stored in this dot end file so it's expecting that in the environment we have some price some price id and then we're also going to set the api key here so i'm going to like just hand wave over this and say that we're going to set this environment variable this is just a tool for checking to make sure that environment variables are set um it's specific to stripe samples it doesn't really matter but i did want to show you where you might set api keys and this is going to apply for like any third party when you're working with rails so back over in rails i'm gonna go to config initializers so these are initializers uh these initializers are ruby files and they're basically scripts that will run at the beginning when the app is booting they only run once and they're gonna they're gonna run when when the app is starting up um so keep that in mind but here we can say uh we can add a new file called stripe.rb um so here now under config initializer stripe.rb we're just going to set stripe.api key here and this will globally set our api key so in sinatra we're globally setting it like this in rails we're going to globally set it but instead of reaching into end when we're in rails we can say rails.application.credentials.dig and then we can pass it like a list of a list of keys that we're going to reach into the credentials file so i'm going to say stripe and api key and that's going to globally set our stripe api key now this app rails the application.credentials thing is gonna is a it's it's part of rails and um where do these end up okay so credentials.yaml.enc is the encrypted credentials so right now if you try to open that file and just like edit it directly you'll notice that it's like this blob that you can't read or understand that's because it's encrypted based on this master key so the master dot key allows you to encrypt credentials.yaml now this master dot key in rails is get ignored so if you look at oh gosh that's nasty so if you open up dot get ignore we'll see that master dot key is ignored and this is ignored because we don't want to commit this or publish this anywhere because this is the key that can be used to decrypt that credentials file so we are going to commit and push that credentials file it will be encrypted but we don't want to pass our master dot key anywhere instead we're going to manage that manually and anywhere that we're deploying to in production we're going to take that the value for that key and set it as the the value in environment variable so heroku config set yeah so for heroku you run heroku config colon set and then you set this environment variable rails underscore master underscore key and you just set it to that value so like whatever the value is of your master key you set that value and that will allow you to decrypt those credentials so um let's see what do we want to do all right uh we want to say rails oh yeah you might be wondering like how do you actually set those values then so rails credentials colon edit is the command and you have to tell it which editor you want to use when you're editing this so we set this editor environment variable and then we call rails credentials colon edit that'll open up our credentials file and allow us to set some values so what i like to do is um we can create this top level stripe key and we'll say api key is our api key and then we might say like public key is our public key and webhook secret is our webhook secret so these are all api keys you can find in the stripe dashboard and again we're just working on this line from the sinatra's server.rb right now we're setting the value for our secret publishable and um and web hook signing secret these are the three ap these are three api keys you can find in your stripe dashboard we have all episode all about authentication with ruby um and so you might want to go check out that episode but by setting these values here when we close the editor it's going to encrypt this file so one other thing we need in order to yeah well yeah let's just we'll call that good so i'm going to close vim and when i do so it's going to re-encrypt this file all right so now when we run stripe this stripe initializer it's going to reach into application credentials it'll deserialize those and it's going to pull out the stripe the stripe the top level stripe key and then underneath that it's api key and so that should set our stripe api key we can check this by saying rails c or rails console and this opens up the rails console for us and then we can just quickly check quickly as in okay so stripe price.list or something see if it'll actually fetch our ap or prices and it does this means our api key is set successfully um and was set during uh in that initializer when it was booting up rails console and that like loads the the app for you okay uh set static to true this allows us to serve um so this is back in sinatra again set is a method that comes from sinatra and these are a bunch of config variables that you can set and configure as part of sinatra one of them is static true this allows us to serve static assets with rails instead of you don't need to do that you can just put you can just put files in this public directory public folder in the sample we specify the public folder as like one directory up and over into this client so again nothing you don't have to do anything there for port 4242 um when you start a rails app um you can specify the port i can't remember exactly the format but yeah okay so dash dash port 4242 should fire it up on four two four two um okay i haven't so when you have a brand new rails app you have to run rake db create uh and you can you can like stack these so rake db create this will create our database locally if i have postgres running and i do and then dbmigrate will run all of our migrations that um haven't run or need to run uh okay so i'm gonna start it up again on port 4242 we refresh the page here come on down okay yeah you're on rails all right so rails app is up it's running and we're off to the races bind uh this is just binding it to this specific ip address which is a loopback address and i don't think we need to worry about that instead it's binding to one two seven zero zero one which is fine this zero zero zero zero is something that we're doing to help test these in ci so you don't have to worry about that all right let's go on to the next step here so get slash when you receive a request to the root route send this file back and right now we're sending back some index.html and that is this html content here so i'm just going to copy that and then come back over to rails and in public we have there's nothing here so this this html is actually just like default html that's coming from rails somewhere deep inside of deep inside of rails there's a couple ways we could do this um we could add index.html here in the public directory and just like paste in all the html from the other example check out rails okay okay so we set up index.html and if we go straight to slash index.html loads that's kind of annoying so instead what we want to do is we don't want to add index.html to the public directory instead we generally will create a new controller just for for rendering like the marketing page or like some root route and so in rails what you might do is say rails g controller um rails g controller static pages and so this is going to generate a static pages controller and then if you pass in any names after that just bare words it'll create views and routes for those so i'm going to say rails g controller static pages for the root route so rails is going to create a new controller called static pages it's creating a whole bunch of other stuff too we don't need this we don't need this and yeah that's probably fine uh okay so after we've created a controller that will live in app controllers so here now you'll notice that we have this new controller called static pages controller and it has one method in here called root and if we look in views we have a static pages directory and that has a page called root.html.erb and so in the static pages root this is kind of the default that comes with the view if you use this rails g controller so if we go to routes so in uh in config so if we go to the config at the top level of the directory here so config and then routes.rb this is where we define all of our routes and how they relate to the controller actions so in here right we want to define a root route so when we receive a request to slash we're going to render back that the html for that root page so we want to say root and then we can just give it static pages and then the pound sign and then the word root and the way that so root is taking in a string and the string value is the name like the the name of the controller and then the pound sign separates the name of the controller with the method that we want to call so if we restart our server here and then change our request to go back to the root route okay refresh you'll see that now we're getting back static pages root so this is the the the view that we can now change so if we wanted to in this root.html.erb which is in an app view app views static pages root html.erb we could just delete all the html that's there and then we could technically copy everything that's over here and dump that in and then refresh this page and then we would see kind of the html that we're getting back from the uh from the existing index.html in the sinatra example the difference is that there's a little bit of wonkiness happening here because in rails there's another view there's like another part of views called layouts so if you go to views layouts this application.html.erb is the default layout that's used for all pages that are rendered when you're loading these controllers so there's actually some like basic html and in the body there's this yield method which is using embedded ruby right and calling yield and when it um when it's generating the html that's going to be returned to the client this yield is going to be replaced by whatever is in the view so right now in the view we already have some html and a bunch of stuff in the head but we don't actually want any of that because the only thing that like generally all of this stuff would go in your template in your application html erb template and then you would really only need whatever content is like generally in the body inside of your view there's probably other things here that we would want to pull out and put up in application html erb but for now we'll just say like whatever and we'll kind of run it like this okay um let's see what's what's next so so this is that's kind of how you would add this get for the slash is you add this controller action uh routes you add a controller actually or i'm sorry you add a route that uses this special root method and the root method takes in a string and the string is of this form and that allows you to return content for the root route let's move on to the next one so slash config in this case you might call this like configs controller or something right so rails rails g controller we need a controller because we we need a controller action that is mapped directly to this slash config route that's being that's receiving a request so we'll say rails g controller configs and there are some conventions that rails follows so you always want to have a pluralized controller so um it's kind of weird you might you might want to call the controller config controller but you want to yeah just pluralize it and it'll it'll help you so what we can do now is go back to our roots and now we want to add a get route that goes to configs slash show okay so in the configs controller we can make a show method and the show method is going to return what is it going to return it's going to return this stuff so i'm just going to copy this whole thing so over here this is what it is in sinatra and then instead we're gonna say uh oh yeah get sorry this this is uh get to uh slash config goes to configs show and in the show method we don't need to specify the content type as application json we do need to retrieve a price so we can say price is equal to stripe price.retrieve and then pass in a price id and then now this is where we're going to render back the json so in sinatra the return value of the block so this do end block the return value of the block is what's returned to the client in rails we have to call the r either render or redirect we can only do it once per controller action and if some cases you might want to either render or redirect depending on the logic that's based on the controller in this case we want to render json so we can say render and then pass it this hash where the first key is json and the value is some dictionary and in this dictionary i'm actually just going to copy this and okay so the unit amount is going to be price dot unit amount and the currency is going to be price.currency and then we want our public key so here we can say rails.credentials or rails.application credentials.dig stripe public key all right so this should render back this the json for this dictionary um all right so let's make a curl request to localhost 4242 config and that should make a get request and it did and we got back this data here so that's that's working as expected and that's how you define a um a that's one of the ways you can define a route so like technically you could say there's a there's a couple other helper methods in rails you can say resources uh configs and this with this will actually create like uh configs slash this is like gives you like the in this calls like the index method on the configs controller or config one and this this generally calls the uh the show method on controller or slash config new this is going to call the new uh action slash config slash one slash edit um and so on and so forth right and this actually when you when you use the resources helper that will create seven routes for you and it's just gonna create all of them so you could also specify that you only want like some i only want the index or i only want show or i want show and new okay you could also do accept and then we'll do certain ones the one reason why you might want to use resources is that it follows a convention it's super conventional it's really easy if you're an experienced rails dev to jump in to an application where it's following all these conventions and using resources everywhere so that's helpful and something to keep in mind something that's a little bit lesser known actually i'm just going to leave this up yeah no whatever is that you can say resource config and i believe that should map to the the same configs controller um but it won't have an index action and it won't have a so this won't have an index action which returns the list and it won't have um what are the other ones uh i can't remember um but so this is this is good so let's keep going what else do we have what else do we have here we have um get checkout session so in sinatra or in this sample we call it checkout dash session and generally by convention we would we would have the post method create the checkout session and the get method retrieve the checkout session so let's do that like the rails way i'm going to say rails g controller check out sessions controller and we want yeah so uh we'll create it without any views to start go to routes and we're gonna say resources check out sessions and this is going to map to check out sessions controller and we want a show method which is going to return it and we want a create method so create this is a controller action that maps to receiving a post request to like slash checkout underscore sessions so post to checkout sessions which is the same actually yeah let's just copy copy this okay and then i'm gonna put it in a comment too so this is what came from sinatra okay all right my computer is telling me that the disk space is almost full so instead of create dash checkout dash session we're just going to receive to like checkout session all right so in rails you um when you're receiving a post request you don't need to specify the content type that's fine the data that you receive is going to um be available rather than saying like json.parse here so in sinatra you have to like manually parse the request body in rails you do not need to manually request parse the request body instead all of the data is available in params so the request body that's being sent to us can be accessed through this params method that's on the controller action so we don't actually need this so here we can say like use params instead so here we're going to say like data is equal to params or something right or down yeah let's do that all right so creating the checkout session this is all actually the same um the domain here this is an environment variable for the sample but you can we can just set it to a localhost 4242 slash whatever that's that's fine all right payment method types all of this stuff is the same data quantity so you can act technically in rails you can access this either with strings or values i think the the params the type of this params object is called hash with indifferent access meaning you can you can either use string values or you can use uh symbols to access the keys so i'm just passing that in like that and then the price here is going to be the id of our price again um that we passed in you again you can use that same credentials thing that we talked about earlier to store that if you want it turns out that session is also a keyword in rails um this is where you how you can manage like cookies or you can tag someone with with uh you can you can use the session to manage state between the client and the server um so i'm actually call this a checkout session instead of session and again here instead of calling.2.json and just returning this we want to say render json and then have that be the result that's returned to us so now let's just test this out so if i send a post request to slash checkout underscore sessions and the post request dash d and i think it what did it expect from params quantity so we're going to pass it quantity is three okay uh we got an error all right what's going on here hard to read hard to read the error we got some error let's look at the server log okay in the server log we see invalid authenticity token okay so one thing that happens for you by default with rails is that it has csrf protection um and so right now this controller is checking for this special csrf token to be in the headers i'm going to disable that for now um you should you should just keep it because it's valuable uh and you need to pass it from the front end to the back end and we'll show how to do this in other examples but for now skip b4 action verify skip yeah verify authenticity token we'll rerun the same thing nope and exception was caught what do we got now missing required params line items quantity data quantity data is params i'm just going to pass params quantity there did i spell it wrong quantity oh i wonder if no yeah that should be fine missing required params quantity all right what's going on here oh okay so in my request i didn't pass the header telling it that it is content type application json so i don't think it's deserializing it yeah okay so now we got back our session id this is exactly what we expect um so this is totally working now um so now we have yeah so we've translated this this this big blob from sinatra for creating a checkout session to this new create thing and i think data equals params this should still work now um cool totally works and we're off to the races all right let's let's update this show action so we are going to retrieve the checkout session is equal to stripe checkout session.retrieve params id so for rails params id like when we hit this when we hit the show action here it's going to come to check out sessions slash and then like some id value and this is variable you can set this to whatever you want and that'll be available in params id and so what we're going to do here is i'm going to take the id of the checkout session the stripe checkout session that we just created so this long cs underscore test blah blah and we'll pass that as our id and use that to look up and retrieve the checkout session and then render it as json so render json of checkout session we'll just render that back and that should be all that we need in order to retrieve the checkout session so i can say now if i say copy that check out sessions slash whoops slash and then put post or paste in the id then we retrieve and pull back the entire checkout session so that's that's kind of how you might translate that note that uh we're not supporting this session id thing it's just a different shape of a name but this is kind of like the rails way to do it so i'm doing it this way um all right the last one here is for a web hook so we want to receive a post request to slash webhook so it would create because this has nothing to do with checkout sessions we're not like creating a checkout session or retrieving a checkout session we're going to receive a web hook request which is a post request from stripe so here i'm going to say rails g controller web hooks and we can follow or we can use that same trick for routes with that we did for resource where it's singular so we can say resource web hook or we could say post to slash web hook goes to web hooks slash or pound create so i'm just going to say resource web hook and then we're going to go to our terminal here and say stripe listen dash dash forward here let's see stripe listen forward to localhost 4242 web hook this will set up a direct connection between my stripe account and my local machine and let's go to the web hooks controller and add a method in here for create def create this is we're going to receive post requests and then we can just copy this entire thing and come back over here let's say from sinatra all right scooch you in comment you out okay so what do we want to do we're translating this from sinatra to rails okay so the webhook signing secret is no longer in the end now it's in rails.application.credentials dig stripe webhook secret uh we no longer need to do request.body.read instead we can just construct the event actually yeah no okay so for web hooks we actually do want to do request.body.read this is a special case that we don't want to use params because we want to pass in the raw payload as raw as possible um and then in in sinatra it has this like status 400 thing that you can do instead what you might want to do is say render json give it some json and then say status like um bad request or just status 400 that way you can you can pass a message back that says like failed to parse webhook event or something and then you can delete status you do want to return early because you can only call render or redirect once so i'm just going to copy that and use that in both spots otherwise we're just going to parse the payload symbolize the names construct from okay so all of that ends up being the same and then instead of just returning status success here we want to say render json of that back and we don't need the content type anymore um uh okay so let's open a new tab and say stripe trigger checkout dot session dot completed oops and that will create the checkout session pay for something and check out okay so we're getting four two two ah because we need to uh disable um verification of authenticity tokens this you do wanna do in in production you can you can safely disable csrf checking for web hook endpoint because the only um the only valid way that this should be accessed is from stripe so stripe is going to send post requests to your web hooks control this is a really common thing that you'll need for most third parties like anytime you're receiving a web hook notification you want to disable csrf did we stop our server yes okay we don't have a server uh all right so no no no no no rails okay restarting the server and now that that is up and running make sure our listener is working and then trigger our command again and hey look at that 200 200 200 great okay and then because we got to check out session completed event we do ding in the console and we have this payment succeeded thing come out there's there's probably a whole bunch of stuff that's happening in sinatra that i'm not remembering but hopefully that covers everything that you would need to know to translate from a at least from a striped sample that's done in sinatra to a rails application so that was the intention for this this episode was to uh teach you how to convert from a sinatra example and use those code snippets in your rails app so all right if you found this content useful i appreciate that and i would also appreciate uh subscribe it definitely helps helps other folks find the channel and 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