---
title: Dynamically render SVG with Rails
slug: dynamically-render-svg-with-rails
published_at: 2021-02-26 18:00:14 +0000
updated_at: 2026-03-04 20:14:27 +0000
summary: 
description: In this Ruby on Rails tutorial, you&#39;ll learn  how to render SVGs with embedded erb using Ruby on Rails. This trick can be handy for rendering custom SVG then converting and exporting PNGs.  Code: https://github.com/cjavdev/video_automation Twitter: https://twitter.com/cjav_dev Feedback: https://forms.gle/Q31hhjJGsMrvY4mL6  It turns out there&#39;s a really excellent tool called TubeBuddy that already exists and does most of what I was planning to build. I&#39;ve started using TubeBuddy in the past few months and really like it. If you use this link to buy a license, I&#39;ll get a small cut for being an affiliate: https://www.tubebuddy.com/cjavdev. #rails #rubyonrails
tags: [Render SVG with Ruby, Render SVG with Rails, SVG to PNG, Ruby on Rails, ERB, SVG ERB Template, ERB Templating with Ruby, Ruby, ruby on rails (software), ruby on rails for beginners, ruby on rails projects, ruby on rails 2020, ruby on rails 2021, ruby on rails 6, svg to png javascript]
views: 1371
author: CJ Avilla
url: https://www.cjav.dev/videos/dynamically-render-svg-with-rails
youtube_url: https://www.youtube.com/watch?v=Ij7l-yOWaso
youtube_id: Ij7l-yOWaso
embed_url: https://www.youtube.com/embed/Ij7l-yOWaso
thumbnail_url: https://i.ytimg.com/vi/Ij7l-yOWaso/hqdefault.jpg
type: video
---

# Dynamically render SVG with Rails

*Published: February 26, 2021*
*Views: 1371*

## Watch

[Watch on YouTube](https://www.youtube.com/watch?v=Ij7l-yOWaso)

[![Dynamically render SVG with Rails](https://i.ytimg.com/vi/Ij7l-yOWaso/hqdefault.jpg)](https://www.youtube.com/watch?v=Ij7l-yOWaso)

## Description

In this Ruby on Rails tutorial, you&#39;ll learn  how to render SVGs with embedded erb using Ruby on Rails. This trick can be handy for rendering custom SVG then converting and exporting PNGs.

Code: https://github.com/cjavdev/video_automation
Twitter: https://twitter.com/cjav_dev
Feedback: https://forms.gle/Q31hhjJGsMrvY4mL6

It turns out there&#39;s a really excellent tool called TubeBuddy that already exists and does most of what I was planning to build. I&#39;ve started using TubeBuddy in the past few months and really like it. If you use this link to buy a license, I&#39;ll get a small cut for being an affiliate: https://www.tubebuddy.com/cjavdev.
#rails #rubyonrails

## Transcript

hey what&#39;s up everyone in the last episode i was talking about the process for converting for from an svg into a png uh we built our svg in figma and then went through the whole process of how do you get this uh get the font families and the font faces rendering correctly when converting to svg using html canvas so uh if you want to go check that out head back to the last episode but in this episode i wanted to like show how we can take this tool that we have renderings the subheading and the heading and then render that based on our video data so in our this is still like so nasty uh but um in our list of videos here like we have this you know video description manager thing and we have a sync button that allows us to click a button that will sync the description update directly to youtube and so yeah this is this is pretty pretty interesting for the description but i wanted to uh extend that so that we can use it to also generate thumbnails uh rather than having to like manually create the thumbnails in figma every single time so we&#39;ve got something working that will render a png from an svg the next step that i wanted to take was let&#39;s let&#39;s build out the or let&#39;s figure out how to take that um how to take that thumbnail png file and then um i don&#39;t know yeah should we try like directly uploading directly to the youtube api i don&#39;t know so let&#39;s see um let&#39;s see if we can update our video show page to at least render the png to the show page here so let&#39;s let&#39;s see how do we want to do this or should we keep it as a separate thing so right now if you go to slash thumb that will render just our basic thing here so let&#39;s let&#39;s go to the videos controller and make our thumb thing dynamic so if we say def thumb we didn&#39;t have an action before we just had a view so we have right now we have a view under videos for thumb.html.erb this is just reading in the thumbdemo.svg file and so now we&#39;ll at least we&#39;ll have access to the video object in our thumb so here we can just say like uh video dot i don&#39;t know what does a video have title right okay so if we refresh the page the video title is now at the top there the other thing i think that we need potentially is like either what series that the video is in or the subtitle so let&#39;s go let&#39;s go add a subtitle um to videos okay so add subtitle to videos and then give it subtitle when you&#39;re generating migrations if you use this pattern like sometimes it&#39;s a little bit of black magic like to get it perfect but i think if the name of the table is at the end and then you give it like the list of fields you want to add it&#39;ll automatically add those following like the default pattern so we&#39;re going to add a new column to videos called subtitle uh raked migrate let&#39;s see if this works cool um and then oh xcode wants stuff sure i&#39;m sure it&#39;s legit okay all right so the next thing we want to do here is go to our thumb dot html.erb and let&#39;s also render the video.sub title here and let&#39;s go to the video form and make it so that we can enter in a subtitle so we&#39;ve got the name [Music] what is this oh no wrong wrong form videos edit uh and we&#39;ve got a title let&#39;s give it a subtitle i&#39;m just going to refine and replace title with subtitle and then we&#39;ll call this sub i don&#39;t know i don&#39;t actually know is it two words or something i don&#39;t know hard to say uh videos controller let&#39;s allow the subtitle to be passed in also subtitle okay so now if we come back to our videos slash four and we click edit now we have a subtitle so the title here is actually going to be data modeling with active record for um for video automation tool and then the subtitle is going to be youtube api video description or video automation tool what&#39;s cool is we can go back and change the subtitles later and that will like regenerate the thumbnail it&#39;ll regenerate a whole bunch of stuff so the person i&#39;m in this video we don&#39;t have any chapter markers yet but we&#39;ve got a bunch of tags so we click update video and now if we go to the thumb here we should see okay data modeling with active record tool okay youtube okay so this is the stuff that we want to put into the svg uh and so for right now the svg is just like a file inside of public it&#39;s just inside of the public directory it&#39;s called demo or thumb demo dot svg and in here we have our our svg content that&#39;s being rendered out what i think we want to do is move that into be like svg.erb or something in order to like try to render this out so let&#39;s see videos let&#39;s add um uh thumb svg or thumb dot yeah let&#39;s see thumb svg.svg.erb this is going to be super weird um is this what we want to do uh i don&#39;t know i don&#39;t know let&#39;s just go down the route let&#39;s go down this route so actually let&#39;s just rename um we&#39;ll just move this thing to thumb base.svg.erb and we&#39;ll move it from public into app views video okay and then we&#39;ll delete this thing okay so we&#39;ve got this new file thumb based svg.erb i don&#39;t actually know this how this is going to render um but let&#39;s yeah let&#39;s give it a whirl so in our thumb.html.erb rather than just reading in this thumbdemo.svg file we want to like actually read in and render the svg based on the video so if we go to video we already are doing something like this with the description right so we&#39;re rent we&#39;re reading in the erb template which is based on description.template and then we are rendering this out so i think um if we if we make another how do we want to do this so let&#39;s say file.read file.join or something let&#39;s see hold on uh what is this okay yeah let&#39;s let&#39;s use this thing okay so we wanna we wanna read in the file but no longer is it at the rails root now it&#39;s going to be in railsroot app views videos thumb dot thumb base dot svg dot erb okay we don&#39;t need this html safe business anymore and now we just need to say like uh template is equal to this thing and then i think we can take this same sort of binding and render out the the new template so instead of description template here we&#39;re going to say like image template and we&#39;re going to render that out so this is going to give us back hopefully thumb.svg will give us back a svg.svg file or like the text for svg file that we can then render out so let&#39;s just see if we can get this to work so here rather than putting the actual svg in the container well let&#39;s say at video.svg what was it called again uh s feed oh thumb svg thumb svg and in fact we probably want to just like remove the spaces and such just to make it super tight and let&#39;s see if we can re-render this page and okay so that totally did not work but it&#39;s it&#39;s giving us the svg but it&#39;s it&#39;s in like raw format so i think here we need to say like dot html safe maybe okay sweet so that&#39;s that&#39;s totally working now let&#39;s improve this so that it&#39;s actually using let&#39;s let&#39;s let&#39;s update our svg.erb template so that it&#39;s using our our subheading our subtitle at video.subtitle and at video dot title instead of the text that&#39;s hard coded there and let&#39;s change this from subhead to sub title just so that the class matches the name of the thing that we&#39;re using and we refresh the page subtitle undefined for nil class so oh you know what it&#39;s probably not at video anymore it&#39;s probably just subtitle because the context that we&#39;re passing in is the binding of the instance of the video so let&#39;s see if this works oh my gosh it&#39;s so cool except it&#39;s like it&#39;s not it&#39;s not wrapping nicely um so we got to figure out how to make the text wrap so this is a new and interesting challenge but like okay so let&#39;s just go let&#39;s okay so let&#39;s go let&#39;s make it a little smaller and then go back to our videos and then if we pick like a different video um no that&#39;s a different one that&#39;s weird okay let&#39;s see uh how about like send in ruby and then if we edit send in ruby and we say like the subtitle is ruby meta programming and the title is um object send and then we say i&#39;m in it update video and now if we go to videos 12 slash thumb boom ruby meta programming object send and then we could just like save this image and use that as our thumb if we wanted to so that is it&#39;s so cool it&#39;s like dynamically rendering our thumbnails as expected so that&#39;s super cool um so i think now that i&#39;m thinking about it even more i think we might want to have a different title for the image maybe or like an override or something i don&#39;t know we can we can get to that later so let&#39;s let&#39;s go back to our our video that has like a really long description here data modeling for active record and let&#39;s see if we can get it to wrap like this okay so we need to go whoops to thumb and we need to figure out how to make text wrap in svg so like um let&#39;s see svg okay so it must be using it must be using javascript in order to wrap it so it&#39;s finding rectangle wrapped and using d3 plus so i don&#39;t know if that&#39;s going to work but i am not a huge fan that okay let&#39;s i mean this the the reason why i&#39;m not like super confident that we should do this is because yeah i mean when it when it goes to i don&#39;t know let&#39;s let&#39;s just try it let&#39;s see when it goes to wrap it i don&#39;t know if the the javascript is going to execute and if we&#39;re going to run into the same issue that we ran into with uh getting the text to render so then if we just say like give me the the class for uh or select dot title and then draw let&#39;s see refresh okay so that that actually did work for the svg and for the other images okay so that huh that&#39;ll totally work okay very cool this blocks thing is actually pretty sweet um all right so now what we need to do is figure out uh what our what a good width would be for this text block inspect and then so let&#39;s see so we find our text block and then if we give it a width and let&#39;s say 900 pixels or something does that give us more space no oops okay and like as we&#39;re messing around with it now now it&#39;s a little bit more challenging to experiment because um because d3 is changing um changing the layout and such so like even if we make this bigger right like uh yeah like so those are already shifted so if we make the width like 1920 and re so yeah that doesn&#39;t help us um okay so let&#39;s let&#39;s keep going let&#39;s dig into this d3 uh this d3 tool to see how we can make this work wrecked wrap okay so um class wrap y is 50 pixels okay so the x and y should just give it the position i don&#39;t see a wrap class or i don&#39;t understand why we need that but let&#39;s just try adding it and see if that changes anything i didn&#39;t think so okay we&#39;re gonna delete that um okay so why doesn&#39;t this go further inspect okay so yeah because if even if modeling was on the same line as data that would be better um all right so d3 plus that&#39;ll work um documentation and the thing that we&#39;re using is text wrap oh wait container wrap text in a single rectangle okay so i wonder if we need a container yeah wait what okay so if we&#39;re looking at this is the rectangle the rectangle is not even wrapping the text that&#39;s so weird okay so our erect wrap that is the text okay so it is it is wrapping it around the text so that&#39;s fine okay so text wrap okay um okay it looks like width is one of the arguments we could pass if the value specified sets the width limit okay so then if we try calling like dot width on the builder here and say like 19 1920 or something i don&#39;t know if it needs to be an integer or in pixels oh look at that sweet okay cool so that is that is awesome it&#39;s totally working um the the where it&#39;s positioned is super weird let&#39;s try moving it to 400 or 420 nope 320. okay um 300 and all right so that&#39;s looking pretty sweet uh let&#39;s change this back to 300. i think it&#39;s okay if it goes over the face right like if it&#39;s over the top of the image here but if you wanted something different i expect that you could probably do something like all right make the width only like 1800 or something and then it would probably wrap a little earlier maybe oh yeah okay so 1700 yeah all right so whatever i&#39;m just going to leave it at 1920 and if it covers the face that&#39;s totally cool like whatever um and then we could probably give it like a max height or something let&#39;s see overflow max lines okay so max line seems good because we probably want like at most three lines so we can say dot max lines three and then if we oh what that&#39;s weird max max lines okay all right that didn&#39;t work as expected and isn&#39;t super important and we can just make sure that our like titles are pretty tight so this is cool if we go home and then we check out like a different video here object send and then we go to thumb we are now seeing like that&#39;s that&#39;s working pretty well let&#39;s do another video that&#39;s going to have a long just long a long description so this one view and edit custom descriptions so we say edit and then we can say the title is view and edit custom descriptions and the subtitle is youtube api video animation tool and then we say update the video and then we go to thumb and we see cool view and edit custom descriptions awesome this is okay so this is totally working so now the trick is um number one we really just care about this like png so if we inspect this and we take a look you&#39;ll notice that there&#39;s like a the base64 encoded png object or whatever that came out of this whole process of converting it to png and if we right click and say save image as that will actually download the image and that&#39;s fine but i&#39;m wondering if we want to just take the base64 image and then send that directly to youtube so um yeah so now that we have we&#39;re automatically rendering the descriptions in the svgs i think that&#39;s good for this episode and then in the next episode we will take this base64 encoded png and attempt to upload it to youtube either by we might need to like store it in rails some some way temporarily or something so um because right now our video or our youtube integration is on the on the back end so um yeah so if you want to check that out we&#39;ll that&#39;ll be in the next episode so yeah if you want to if you&#39;re enjoying this content and you want to stay plugged in i would love to hear from you if you want to hit me up on twitter at cjabdev otherwise yeah if you want to like and subscribe that is very much appreciated and uh yeah you&#39;ll i&#39;m working to continue creating content just like this uh for folks like you and so that i can keep learning and having my own stuff that i can look back at and remember how how this all worked so all right see in the next one you

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