Details
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Type:
Bug
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Status: Closed
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Priority:
Minor
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Resolution: Fixed
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Affects Version/s: 2.2.3, 2.3
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Component/s: Quiz
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Labels:
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Testing Instructions:
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Affected Branches:MOODLE_22_STABLE, MOODLE_23_STABLE
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Fixed Branches:MOODLE_22_STABLE, MOODLE_23_STABLE
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Pull from Repository:
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Pull Master Branch:
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Pull Master Diff URL:
Description
I have several hundreds of quiz questions that use TeX to render mathematical equations in Moodle 1.9.
I've just installed the new version of Moodle 2.2. I exported my question categories from Moodle 1.9 in GIF format and imported them to Moodle 2.3. During this process, Moodle 2.2 deletes one of the double backslashes that TeX uses to build mathematical Matrices.
Since I can't upload example files here, I'll leave you with an example of what happened to one of the questions:
-> Question exported from Moodle 1.9
// question: 743 name: InversaCalculo_01
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::InversaCalculo_01::[html]<p><span>A inversa da matriz $$A \= \left[ \{\begin\{array\}1 & 0 & 0\\0 & 1& 0\\1 & 0 & 1\\ \end\{array\}\} \right]$$ é </span></p>\n<p></p>\n<p></p>\n<p></p>{
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=$$\left[ \{\begin\{array\}1 & 0 & 0\\0 & 1& 0\\-1 & 0 & 1\\ \end\{array\}\} \right]$$
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~%-33.333%$$\left[ \{\begin\{array\}1 & 0 & 0\\0 & -1& 0\\1 & 0 & -1\\ \end\{array\}\} \right]$$
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~%-33.333%$$\left[ \{\begin\{array\}1 & 1 & 0\\0 & 1& 0\\1 & 0 & 1\\ \end\{array\}\} \right]$$
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~%-33.333%$$\left[ \{\begin\{array\}-1 & 0 & 0\\0 & 1& 0\\1 & 0 & -1\\ \end\{array\}\} \right]$$
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}
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-> Same question after importing to Moodle 2.2 (the same thing happens in Moodle 2.3)
// question: 4 name: InversaCalculo_01
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::InversaCalculo_01::[html]<p><span>A inversa da matriz $$A \= \left[ \{\begin\{array\}1 & 0 & 0\0 & 1& 0\1 & 0 & 1\ \end\{array\}\} \right]$$ é </span></p>\n<p> </p>\n<p> </p>{
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=<p>$$\left[ \{\begin\{array\}1 & 0 & 0\0 & 1& 0\-1 & 0 & 1\ \end\{array\}\} \right]$$</p>
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~<p>$$\left[ \{\begin\{array\}1 & 0 & 0\0 & -1& 0\1 & 0 & -1\ \end\{array\}\} \right]$$</p>
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~<p>$$\left[ \{\begin\{array\}1 & 1 & 0\0 & 1& 0\1 & 0 & 1\ \end\{array\}\} \right]$$</p>
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~<p>$$\left[ \{\begin\{array\}-1 & 0 & 0\0 & 1& 0\1 & 0 & -1\ \end\{array\}\} \right]$$</p>
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}
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Thank you!
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Actually, this is a known issue: MDL-28540
The problem is that a lot of the characters used by TeX are also special characters used by GIFT. Therefore you need to escape them. That includes \.
I suppose the problem is that Moodle 1.9 is not correctly doing the export It should be exporting \ as
, and
as \\\\.
However, we are not fixing bugs in 1.9 any more.
If you want to transfer questions from 1.9 to 2.x I recommend Moodle XML format.
Hello Tim,
I can confirm that your fix is working. Here is the test I made.
I created a similar multichoice in Moodle 2.3. I exclusively used Dragmath to create the matrix both in questiontext and in choices.
For reference I will upload picture of the question preview and of the display in the editor (both question text and choices) when creating the question. Then I exported it using GIFT format and re-imported it. I find no difference with the original question and the display of math formulas is still OK. I will post the GIFT file so that it is possible to make comparisons with the tex.gift.txt file that you posted.
But if this fix is applied to Moodle, I think that the doc at http://docs.moodle.org/23/en/GIFT#Special_Characters_.7E_.3D_.23_.7B_.7D need to be fixed too because currently it tells NOT to escape the backslash character so this must be changed.
All files from my test with moodle 2.3
Unfortunately fixing broken GIFT files is very difficult because we must escape backslash used as backslash but not backslash used to escape all other special characters !! For instance backslash+bracket used outside of a TeX formula should be left unchanged but inside a TeX formula the backslash should be escaped !!
I will look at MDL-28540 to see if I can make a math GIFT format.
I think import leave \ alone, so to fix an existing GIFT file, just try replacing
with \\\\.
Yes you are right, I hadn't spotted that in Luciana's description : fortunately import leave single backslash untouched. I was able to fix tex.gift.text just by replacing double backslahs by quad backslashs (By the way it's very painfull to have a discussion about backslashs on JIRA !!) and it imported fine.
So I think the docs should be modified
- to enforce the need to escape backslashs when writting files in GIFT format
- to explain the trick to import 1.9 GIFT files
If you are OK I can try to edit the doc page ?
Yes, please edit the docs.
Thanks a lot Tim, integrated to master, 23 and 22
Tested in 2.2 and master. Gift files are now exporting \ characters as expected.
Test passed 
Congratulations!
You've made it into the weekly release!
Thanks for your contribution - here are some random drummers to keep you inspired for the next week!
http://www.youtube.com/watch?v=_QhpHUmVCmY
Here is the test question as a file. The problem definitely happens on import.