---
title: Image upload for markdown input with Stimulus and ActiveStorage
slug: image-upload-for-markdown-input-with-stimulus-and-activestorage
published_at: 2023-02-21 13:00:28 +0000
updated_at: 2026-03-04 20:12:56 +0000
summary: 
description: In this episode, you&#39;ll learn how to add image uploading to inline images into a textarea for markdown.   Jeremy&#39;s blog post: https://hybrd.co/posts/github-issue-style-file-uploader-using-stimulus-and-active-storage  Jeremy&#39;s Twitter: https://twitter.com/jeremysmithco   #rubyonrails #ruby #rails
tags: [cjav_dev, web development tutorials, web development for beginners, vim, ruby, rails, javascript, ruby on rails, active record, ruby on rails tutorial, markdown, image upload, active storage, image upload to textarea for markdown, image upload to textarea for markdown with stimulus, stimulus.js, stimulus.js upload, file upload]
views: 1256
author: CJ Avilla
url: https://www.cjav.dev/videos/image-upload-for-markdown-input-with-stimulus-and-activestorage
youtube_url: https://www.youtube.com/watch?v=rOdtvShwFPE
youtube_id: rOdtvShwFPE
embed_url: https://www.youtube.com/embed/rOdtvShwFPE
thumbnail_url: https://i.ytimg.com/vi/rOdtvShwFPE/hqdefault.jpg
type: video
---

# Image upload for markdown input with Stimulus and ActiveStorage

*Published: February 21, 2023*
*Views: 1256*

## Watch

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

[![Image upload for markdown input with Stimulus and ActiveStorage](https://i.ytimg.com/vi/rOdtvShwFPE/hqdefault.jpg)](https://www.youtube.com/watch?v=rOdtvShwFPE)

## Description

In this episode, you&#39;ll learn how to add image uploading to inline images into a textarea for markdown. 

Jeremy&#39;s blog post: https://hybrd.co/posts/github-issue-style-file-uploader-using-stimulus-and-active-storage 
Jeremy&#39;s Twitter: https://twitter.com/jeremysmithco 

#rubyonrails #ruby #rails

## Transcript

what&#39;s up welcome back in this episode you&#39;ll learn how to add drag and drop file upload to a text area for editing markdown so that you can upload your images super easily so stick around and we&#39;re going to dive into that before I go too far though I really have to acknowledge Jeremy Smith here so go over and follow Jeremy Smith Co on Twitter he wrote up this blog post that was super helpful very simple to follow so I will link to the blog post and Jeremy&#39;s Twitter so go follow Jeremy so the way that this works is we&#39;re going to have a stimulus controller that listens to a couple of different events one is a drop and one is paste and then we&#39;re gonna use active storage direct uploader to upload those files to S3 in this case and then we&#39;ll update the markdown with our little embedded markdown image thing so basically the way that images work is you&#39;re going to have a exclamation point in the front and then some alt text here so this is going to be your alt text and then you&#39;ll have some image if it&#39;s local or if you have an image in the public directory you could do something like image.png or something so this is the markdown format for an image but what I want to be able to do is just grab an image directly from from my finder and drop it in and I want that to upload the image to S3 and then add the text into the markdown field this is how the GitHub issue editor works and so this is something that we want to add to my personal site here for managing articles first things first is we need to make sure that we have active storage set up and working as expected so in config storage.yaml I&#39;m going to come in here and enable Amazon I want to use Amazon S3 in this project I happen to already have my access key and secret access key set there&#39;s another video on this channel showing how to set up active storage and how to get uploading working so for now I&#39;m just going to leave those for later but the bucket that I want to upload these to I Just Called It C job Dev and what I want to do now go over to our development environment so I&#39;m going to go over to development.rb and make sure that our storage settings are going to use Amazon so when you&#39;re just practicing and playing around locally you&#39;ll usually want to write local files so actually let&#39;s start off with local and we can come back later and switch it to Amazon okay the next thing we want to do is we want to use a stimulus controller for managing that input box or at least parts of our form so we&#39;re going to say rails G stimulus and we&#39;re going to call this markdown upload so this is going to be a markdown upload controller and that should have updated our manifest and it should have also created this markdown controller Javascript file for us so let&#39;s open this thing up and now we&#39;re going to be able to use this data Dash controller attribute on the text area input with this markdown Dash upload when it&#39;s connected we&#39;ll just console .log connected and the other thing that we care about is making sure that it was added to our registrations this was the Manifest updating and yeah so this is what happened as like the second part of generating this controller is it added this like manifest thing here there&#39;s a couple different ways to load your your stimulus controllers but this seems to work just fine so what we can do now is go over to our article form.html.arb and where our text area is for our body I want to add some data attributes here so the first one is going to be data Dash controller markdown upload now when we reload this page over here we should see in the console that it was connected so here we see connected so that&#39;s cool so now our markdown controller is being connected now what we want to do is start triggering when things are dropped or pasted into this markdown or into this this text area so the next thing we want to do is say data action is equal to drop on the markdown upload and when that happens call upload or drop upload I think drop upload okay so we need to make a method on the controller called drop upload so we&#39;ll go back to our upload controller and we&#39;ll make a new method here called drop upload that is going to take in an event and we want to prevent the default for that event because usually when you drop something onto the page it ends up like just viewing it in another pane this is actually getting pretty close to what we want to do but for now we&#39;re just going to say eat up prevent default and we&#39;re going to say console.log I don&#39;t know uploading files okay so let&#39;s just refresh our page here and see what happens when we try to drop something in there now so we&#39;re just going to drop this Twitter logo in there and now we see this uploading files printed out to the console all right great so the next step here is that we want to actually use the direct upload class that is available through the active storage npm module so this rails active storage gives us this direct upload class that we can then use to upload so here we can create a new upload given the file and some URL and that will go through the process of uploading now the URL that&#39;s right here this is the direct upload URL that is the URL that active storage is giving us when we want to make direct uploads so we&#39;re going to use an Erb method to pull that out and inject it into our text area so this is something that we want to like actually pass in our text area here so we&#39;re going to say data markdown upload URL value is going to be equal to and then there&#39;s this Ruby method that we can call that will give us back the the direct uploads URL and that is from active storage so that&#39;s going to allow us to use this value inside of our controller so we&#39;ll go back to our controller here we want to have static values and the one we care about is this URL that&#39;s going to be available so we have the first thing that we need and that is the direct upload URL the second thing we need is the file so we&#39;re going to get the file from the inputs that are given to us on drop so when we receive that drop event the event is going to have this data.transfer.files and we can iterate over each of those files and call upload so it&#39;s possible we get several files dropped onto us and so then what we&#39;re going to want to do is say iterate over the files that were given to us so e dot data transfer.files should have all the files that we want to when we are uploading so again we need to import direct upload from rails active storage now as soon as I save this file the my server is going to crash probably because I don&#39;t think I have this npm install I need to add this rails active storage package okay and now we should be able to say bin Dev and all right so now when we refresh the page over here okay let&#39;s see what we get now so if we drag on a file and drop it now we see this file list so it has one file so the zeroth index here the object is of type file it has the name the size and it&#39;s an image and all this all these details so we&#39;re going to take that file and upload it directly to in in the local case we&#39;re going to directly upload it to our local running file server but in in practice we&#39;re going to switch it to S3 and that&#39;ll upload directly to S3 give us back some URLs that we can use okay so the next step here is that we want to take these files we want to iterate over each of them and call upload on them so we&#39;re going to just say something like array Dot from dot for each file and then we want to call in fact we can just call like this dot upload file and here we can say upload file I don&#39;t know if we&#39;re going to need access to this inside of here but we&#39;ll come back and modify The Binding if so all right so this says that we&#39;re going to try uploading all the files so for each file that we want to that we get we&#39;re going to create that upload object and that&#39;s going to be a new direct upload and the first object is going to be the file and the second object is going to be this dot URL value so we do in fact need bind this okay we&#39;re calling bind this so that the function that we&#39;re passing into four each is explicitly bound to this instance of the markdown upload controller another way that we could have written this would have been just something like for each file this dot upload file and then execute this with passing in F and by doing it this way we continue to maintain The Binding of this so two different ways of doing that okay we&#39;ll just clean this up a hair and let&#39;s take a look alright so back over in the active storage documentation you&#39;ll see that it has this upload.create method that takes a callback that will resolve with an error or a blob so we can grab this upload call and let&#39;s just drop this let&#39;s just drop this inside of our function here so if if there was an error we will log out the error so we&#39;ll just say something like alert error I don&#39;t know what the shape of that error is going to look like but because this is just something that&#39;s used by me that should be fine okay so then the next thing we want to do is we&#39;re going to get a few different pieces of information off of this blob so let&#39;s console.log The Blob console.der The Blob and we&#39;ll just use that for now to see what we&#39;re getting back from The Blob data so we&#39;ll come back over here to our application drop in an image and this is our blob data that we&#39;re getting back so we&#39;re going to have this signed globally unique identifier we have the size the checksum we know that it&#39;s an image and here we have the file name Etc so we can use this information to then construct a URL that we want to go and see this file that we uploaded again if we look at the documentation we see this blob.signed ID and active storage is going to give us some URLs so here&#39;s an example it&#39;s going to be like slash rail select active storage blobs then the signed ID and then the file name so if we just copy this and take a look at what we get back here so let&#39;s paste this in localhost 3000 slash rails active storage so right now that&#39;s not going to do anything but now if we grab the signed ID for the blob so we&#39;ll copy that and we want to replace the signed ID in the URL that should give us back beginning and then we also I think need the file name so we&#39;ll just grab the file name here it&#39;s going to be like the Twitter logo and if we hit enter now we see this image so notice that this is hosted at localhost 3000 eventually we&#39;re going to upload that to S3 but if we wanted to we could say bang Twitter logo is our alt text and then we could paste in that URL and if we said submit now we have this blog post here that has the image that is embedded in it so this is working the next step is just to construct the URL here given the signed ID from The Blob and then the file name for the blob so that we can construct some sort of URL that looks like this and we want to do that client side so here we&#39;re going to do something like um markdoc or Mark II markdown URL and we&#39;re going to take in the blob and we&#39;re going to return that URL yeah so it&#39;s going to be that exactly okay thank you copilot all right so if we were to just console Dot yeah so the other thing that we need to do here is if it&#39;s an image we want this exclamation point But if it&#39;s other types of files then we we don&#39;t so for now we&#39;ll just assume that they&#39;re all images and then if you wanted to handle stuff that was not images you would need to figure out the content type of the file that&#39;s being uploaded and then decide whether or not you want to show the exclamation point and then finally what we want to do is figure out where this range is of selected text and then we need to go through and actually like insert into the right spot in our text editor so we&#39;re going to set this range from start to end to be the value from our markdown blob okay and again like in this example it does show you how to check if it&#39;s an image and if it is an image figure out how to do the prefix thing so head over take a look at the blog post we&#39;re going to use selection start and selection end let&#39;s grab this grab reference to this text area so it&#39;s just called body let&#39;s see const body document dot get element by ID body okay so this is our body now if we said something like body dot select selection start that gives us the character where the selection starts so this is the 38th character in is the that R and then we have selection end that&#39;s going to be where our selection stopped and so if when we&#39;re dropping something in here so let&#39;s say let&#39;s actually make this a little different we&#39;ll do so let&#39;s try to drop it like right here and then we will also console.log this Dot element.selectionstart and selection end and let&#39;s try to drop in this image again right here oh you know what we need to refresh yeah okay drop it in okay 242 and 242. so it must have added it directly at the end of this stuff here but that&#39;s fine so that&#39;s going to drop the image in between so if we try to do it here okay yeah so then that would have ended up in between so 162 and 162. cool and if we did it after 10 see what we get here there we go 11 and 11. so that&#39;s where the object would have landed okay so now what we want to do is say we want to set the text value or in that range so starting from 11 to 11 we want to insert some text and that text is going to be that URL constructed from the markdown URL so we can say set range text this the element dot set range text from this is going to be our like text and then we&#39;re going to have selection start selection end and that should be good so here we want to pass in our markdown and that should work I think so let&#39;s come back over here refresh the page and highlight all this test and then let&#39;s actually test more and say that we happened to drop an image in between the two all right cool so that uploaded the image and it injected it directly into our markdown and it has the correct format and everything so if we say submit now we have test at the top we have test more at the bottom and the image is uploading so another thing that I do all the time when I&#39;m writing these articles is I&#39;ll take a snapshot and add it to the clipboard you can do I don&#39;t know alt control Shift 4 or something and let&#39;s say you take a screenshot now that like gets added to the clipboard and if I paste I want it to I want to be able to like command V to paste the image in here and have that also upload so in order to do that we needed to add a second sort of flow here so right now we have our drop upload let&#39;s also add our paste upload that&#39;s going to be pretty similar eat up prevent default and eventually we are going to upload some files but the API is just slightly different so paste upload we&#39;re going to check to make sure that there is something on the clipboard so we&#39;re going to check to see if there&#39;s something on the clipboard and then otherwise we&#39;re going to go through the clipboard data.files and for each of those we will again call Dot for each and we&#39;ll upload that so this is actually called e okay so now we&#39;re going to go through each of those files that are on the clipboard call upload file for each one and that should end up inserting it the same way that we want that we want that to happen over here oh you know what we didn&#39;t do we didn&#39;t wire up this paste upload method okay so we got to go to our article form and in our data action we need paste to the markdown upload controller and we&#39;re going to call this paste upload method so save that refresh the page and let&#39;s take a screenshot again and paste it in boom look at that okay so let&#39;s see if that&#39;s actually the pasted one and not something else nice okay so this is the screenshot that we just took so that is now being uploaded locally cool so then yeah the rest is just a matter of going to if we were to go to development here and where we have this set up for local we can switch this to Amazon and again we would want to also go to production and go to our storage and make sure that we are using Amazon in production okay refresh this and we&#39;ll go back to slash edit and let&#39;s just remove all of these and we&#39;ll say did this upload to Amazon and we will drop in another picture here so yeah let&#39;s use a headshot sure okay submit all right uploaded and now if we look at the yeah so if we look at the element here you&#39;ll notice that the URL is still going to this local storage whatever URL and this is oh it&#39;s technically still on disk okay so that did not work so we got to restart our server I think so let&#39;s restart the server come back over here delete we&#39;ll go back over here edit and let&#39;s drop something else you might be wondering why I&#39;m typing edit in and that&#39;s because I just haven&#39;t added a button to go to edit because it&#39;s just me again that&#39;s using this form so let&#39;s say submit all right did this upload to Amazon because it&#39;s like lagged when it was loading I think it might have actually worked so now if we look at this image all right so now you notice that it&#39;s this one is hosted on Amazon aws.com so now it&#39;s the direct upload URL is different rather than being for our local disk storage now it&#39;s uploading it to Amazon S3 and working just the same and we have the same sort of tooling and functionality so this is pretty fun this is going to speed up my process so much before I&#39;m embarrassed to say that I was just like manually adding images to my public directory and then linking to them in different blog posts but I want to add much more like a lot more images and screenshots and Detail in future blog posts and this will make it so much faster so thanks so much for watching and we&#39;ll see in the next one

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