JSON in Ruby

Myhand

OK, with the single quote now working, I have run into the next (and hopefully the last) problem. It appears as if the

WebDialog.execute_script

method strips all \ characters from its arguments as it passes it into JavaScript. I think it is because it does a eval() call on the JS.

e.g.

js_command = "material_maintenance.Sketchup.callUI(\"a string >\\< with a \\\" in the middle\")"; puts "js_command = #{js_command}";

produces this in the Ruby console:


js_command = material_maintenance.Sketchup.callUI("a string >\< with a \" in the middle")

and this when you print the parameter to the callUI function as it hits JS.


a string >< with a " in the middle

replacing js_command with

js_command = "material_maintenance.Sketchup.callUI(\"a string >\\u005c\\u0022< with a \\u005c\\u0022 in the middle\")"

works and produces the desired output in JS


a string >\"< with a \" in the middle

but this feels a bit clunky. Any other ideas?

Aerilius

You need to escape \ characters in the double-quoted javascript code that you want to bring into the webdialog (this first escaping is what makes a valid Ruby string).
%(#000000)["alert('C:\users')"] # bad Ruby string
%(#000000)["alert('C:\\users')"] # good Ruby string
In the webdialog, the string arrives written in a script element. As always, the same escaping rules apply again:
%(#000000)[alert('C:\users')] // bad JavaScript code
%(#000000)[alert('C:\\users')] // good JavaScript code

=> So finally this means we need double escaping on the Ruby side!
%(#000000)["alert('C:\\\\users')"] # Ruby string

P.S: SketchUp does not offer error handling for syntax errors in the Ruby-to-JavaScript string. Assuming my js contains user generated data with unknown characters, or is broken (truncated), we will definitely get a popup about "Syntax Error" that we cannot suppress and handle in other ways. In order to get control of such errors, we could send the code as a JavaScript string and eval() it:
%(#000000)[webdialog.execute_script("try{eval(\"}bad_$yn7aX{\")}catch(e){}")]

All of this is an old story and to many people have suffered, discovered, solved this and re-invented the wheel. For an all-in-one solution that covers this and many other WebDialog issues (for example you will discovered that when sending \\\ from JS to Ruby, it randomly drops some ), please take a look and make use of the WebDialogX project.

thomthom

@myhand said:

method strips all \ characters from its arguments as it passes it into JavaScript. I think it is because it does a eval() call on the JS.

Almost - it injects a SCRIPT element in the webdialog - does pretty much the same thing.
So when you pass data to the WebDialog and something is amiss - check the string you're sending to the WebDialog - is it valid? What throws people off is that you have the quoting needed to create the Ruby string with the JS - and within the JS string you need to follow JS's own quoting and escaping rules.

(Because execute_script adds a SCRIPT element for every call I prefer to remove the SCRIPT element on the JS side afterwards - as I don't like the idea of the DOM tree flooded with SCRIPT elements. I've yet to experience problems with it - but there's something about it that makes my OCD-nerve tingle.)

Myhand

@aerilius said:

=> So finally this means we need double escaping on the Ruby side!
%(#000000)["alert('C:\\\\users')"] # Ruby string

I am sure I tried this last night, but will do some further tests again tonight.

@aerilius said:

In order to get control of such errors, we could send the code as a JavaScript string and eval() it:
%(#000000)[webdialog.execute_script("try{eval(\"}bad_$yn7aX{\")}catch(e){}")]
[/size]

Nice idea, I might use this going forward.

@aerilius said:

please take a look and make use of the WebDialogX project.

I cannot access the content. I get "You do not have access to the wiki." message, even after I have registered.

Dan Rathbun

@myhand said:

@aerilius said:

please take a look and make use of the WebDialogX project.

I cannot access the content. I get "You do not have access to the wiki." message, even after I have registered.

Sorry, it is a 5-slot private repository at this time, and we really need very experienced Rubyists for the slots.

And you are kinda re-inventing the wheel. Js has %(#8000BF)[escape()] and %(#8000BF)[unescape()], and Ruby has them in the URI library.

See topic: http://sketchucation.com/forums/viewtopic.php?f=180&t=49183#p442102

In fact I would vote for Ruby's URI::Escape module to be mixed into the SketchUp API UI::WebDialog class.

Myhand

@dan rathbun said:

Sorry, it is a 5-slot private repository at this time, and we really need very experienced Rubyists for the slots.

No problem Dan, I only looked there as Aerilius recommended I do so.

@dan rathbun said:

And you are kinda re-inventing the wheel. Js has %(#8000BF)[escape()] and %(#8000BF)[unescape()], and Ruby has them in the URI library.

See topic: http://sketchucation.com/forums/viewtopic.php?f=180&t=49183#p442102

In fact I would vote for Ruby's URI::Escape module to be mixed into the SketchUp API UI::WebDialog class.

Thank you, I will try the URI library (I already use escape() in my latest JS code). I do not really want to reinvent the wheel, hence me asking the question here.

Myhand

@aerilius said:

You need to escape \ characters in the double-quoted javascript code that you want to bring into the webdialog (this first escaping is what makes a valid Ruby string).
%(#000000)["alert('C:\users')"] # bad Ruby string
%(#000000)["alert('C:\\users')"] # good Ruby string

In the webdialog, the string arrives written in a script element. As always, the same escaping rules apply again:
%(#000000)[alert('C:\users')] // bad JavaScript code
%(#000000)[alert('C:\\users')] // good JavaScript code

=> So finally this means we need double escaping on the Ruby side!
%(#000000)["alert('C:\\\\users')"] # Ruby string

Thanks for a very clear explanation. I tried this last night and it worked. Need 7 '''s for a "!

thomthom

@myhand said:

Need 7 '''s for a "!

What?

Myhand

@dan rathbun said:

And you are kinda re-inventing the wheel. Js has %(#8000BF)[escape()] and %(#8000BF)[unescape()], and Ruby has them in the URI library.

See topic: http://sketchucation.com/forums/viewtopic.php?f=180&t=49183#p442102

Thanks for this Dan! It works well, and I do not need to remember the number of slashes.

I see that escape() and unescape() are deprecated though and that you are recommended to use

decodeURI()

decodeURIComponent()

Which do you recommend or should I continue with unescape()?

Myhand

@thomthom said:

@myhand said:

Need 7 '''s for a "!

What?

Sorry, meant you need

"a JSON escaped double quote need to be specified like this \\\\\\\" in Ruby for a WebDialog call"

to produce

"a JSON escaped double quote need to be specified like this \" in Ruby for a WebDialog call"

as the parameter of the JS function called.

Dan Rathbun

Hmmm..

given a Js function named say()

.. and a Ruby string:
jarg = %q('a JSON escaped double quote need to be specified like this %q(\") in Ruby for a WebDialog call')

I usually do something like this:

dlg.execute_script("say(#{jarg});")

or I will leave the single quotes out of the jarg string, and put them in at the call ...

jarg = %q(a JSON escaped double quote need to be specified like this %q(\") in Ruby for a WebDialog call.)
dlg.execute_script( "say('" << jarg << "');" )

Dan Rathbun

[quote="Myhand":31wco2xd]I see that %(#8000BF)[escape()] and %(#8000BF)[unescape()] are deprecated (in Javascript,) though, and that you are recommending to use [them]
***%(#BF4000)[
@unknownuser said:

]***

@unknownuser said:

](http://msdn.microsoft.com/en-us/library/dz4x90hk(v)":31wco2xd]The unescape function should not be used to decode Uniform Resource Identifiers (URI). Use decodeURI and decodeURIComponent functions instead.
%(#8000BF)[decodeURI()]
%(#8000BF)[decodeURIComponent()]

Which do you recommend or should I continue with %(#8000BF)[unescape()]?

The old functions are ASCII, the new ones are Unicode.

Taking a look at the most recent released ECMA-262 (but not the latest proposed revision,) the old functions are no longer listed.

see: ECMA-262, 5.1, Global Object: 15.1.3 URI Handling Function Properties
ECMAScript Language Specification
Standard ECMA-262
5.1 Edition / June 2011

Link to the downloadable PDF of the specification.

But you need to handle the situation where an older browser does not have these functions so, write a wrapper in JS:

var unesc = function(uri) {
    var test = false;
    if (typeof(decodeURI) == "function") test = true;
    return test ? decodeURI(uri) ; unescape(uri);
}