Send announcement via API problem: Pragraph marks not preserved

[mmtscn]

Hello,

When I send announcement via API, paragraph marks are not preserved. For instance, the original message is:

this is a test message
this is a test message
this is a test message
this is a test message

on Canvas, it will show this:

this is a test message this is a test message this is a test message this is a test message

(Send message to student API works find. It will preserve the paragraph marks.)

Might be a bug?

[James]

 @mmtscn  

Are you formatting your announcement using HTML ?

<p>this is a test message</p>

<p>this is a test message</p>

<p>this is a test message</p>

<p>this is a test message</p>

Conversations / messages don't support HTML, so line breaks would make sense there. Announcements are expecting HTML, so line breaks are meaningless.

[mmtscn]

Hello James,

Thanks a lot for your explanation. I don't have any html labels.

An example of the shell script is like this:

curl https://canvas.instructure.com/api/v1/courses/myCanvasCourseID/discussion_topics \
-X POST \
-F title="this is a test title" \
-F message="this is a test message.
this is a test message.
this is a test message." \
-F is_announcement=True \
-F published=True \
-H "Authorization: Bearer myCanvasToken" \

If I put

<p>this is a test paragraph</p>
<p>this is a test paragraph</p>
<p>this is a test paragraph</p>

the shell script will not run.

[mmtscn]

I've found the solution here: https://community.canvaslms.com/thread/17931-conversations-api-formatting-multi-line-message 

Replacing "\n" with "<br>" before executing the shell script will preserve the line breaks.

Thanks!

[James · Accepted solution]

You didn't mention that you were using curl.

You need to use --form-string instead of -F. @ and < are special characters in -F. If there are no @ or < then you can just use -F.

Here's what the curl manual says about -F

This enables uploading of binary files etc. To force the 'content' part to be a file, prefix the file name with an @ sign. To just get the content part from a file, prefix the file name with the symbol <. The difference between @ and < is then that @ makes a file get attached in the post as a file upload, while the < makes a text field and just get the contents for that text field from a file.

For --form-string, it says:

(HTTP SMTP IMAP) Similar to -F, --form except that the value string for the named parameter is used literally. Leading '@' and '<' characters, and the ';type=' string in the value have no special meaning. Use this in preference to -F, --form if there's any possibility that the string value may accidentally trigger the '@' or '<' features of -F, --form.

Here's how my request looked, with <token>, <instance>, and <course_id> being replaced.

curl -X POST \
  -F "title=this is a test title" \
  --form-string 'message=<p>This is a test message.</p>
<p>This is a test message.</p>
<p>This is a test message.</p>
<p>This is a test message.</p>' \
  -F "is_announcement=true" \
  -F "published=true" \
  -H "Authorization: Bearer <token>" \
  -H "Accept: application/json" \
  "<instance>/api/v1/courses/<course_id>/discussion_topics"‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

You can also use -d to put all of the fields together like you would for a GET. According to the curl manual, this should be url encoded.

-d "title=This is a test title&message=<p>this is a test messsage.</p><p>this is a test messsage.</p><p>this is a test messsage.</p><p>this is a test messsage.</p>&is_announcement=true&published=true"

Adding a <br> means that you're using HTML, but specifying line breaks. You were asking about paragraphs, which is what the <p></p> element gives you.

[mmtscn]

James,

Thank you so much!

I'm new to API and curl. I just assumed curl was the only way to do it, and I was just using the shell command created by others. I did not see on the official Canvas API that announcement expects html. I heard the first time from you.

Thank you for your detailed explanation. It has solved my problem.

Even better, I also found that semicolon would cut the rest of the paragraph if I just do "-F". It would not be a problem to "--form-string".

[James]

Most people use a programming language and a request library to make the API calls. CURL may be good for testing and PHP commonly uses the CURL library. In Node JS, I use fetch-node because it's similar to what's built into the browser so I am familiar with it, but the other day I used the https library, which is part of the core product.  Some languages like python even have Canvas-specific libraries.

The Canvas API may not say that it expects HTML. It's more of a familiarity with the Canvas and knowing what it does that led me to that statement. When you create an announcement, you get to use HTML. The same thing with discussions, which is the codebase that announcements are built off of.