ProgrammingHelp:Wikka

Revision [4529]

This is an old revision of ProgrammingHelp made by JavaWoman on 2005-01-12 15:39:53.

How would you replace every 2nd occurence of a "needle" in a haystack string? I'm sure you can see where I'm going with this, I want to parse output from a table read so that **'s and //'s are replaced alternately with and etc in a string so I can minimally format table content in the output tales in the forum and calendar actions after stripping out html on the way "in" to the database (both of which pick up on what other wikkausers suggested as desireable features for them). I've searched everywhere on this & spent ages on it and have found bupkuss. Thanks for any guidance. -- GmBowen
Finding a function that replaces only the first occurence in the string led me to the solution. I've coded 3 functions that can be included to turn bold & italics wikka code into html tags for output into a table (such as in my scheduler & wikka forum). Code below....

function str_replace_once($needle, $replace, $haystack) {
// Looks for the first occurence of $needle in $haystack
// and replaces it with $replace.
$pos = strpos($haystack, $needle);
if ($pos === false) {
// Nothing found
return $haystack;
}
return substr_replace($haystack, $replace, $pos, strlen($needle));
}

function bold_formatting_replace($haystack) {
//replaces bold wikka formatting (**) with html bold tags
$needle="**";
$count=(int)(substr_count($haystack, $needle)/2);
$replace="";
$replace2="";
while ($counter<$count)
{
$counter++;
$haystack=str_replace_once($needle, $replace2, str_replace_once($needle, $replace, $haystack));
}
return $haystack;
}

function italics_formatting_replace($haystack) {
//replaces italics wikka formatting (//) with html italics tags
$needle="//";
$count=(int)(substr_count($haystack, $needle)/2);
$replace="";
$replace2="";
while ($counter<$count)
{
$counter++;
$haystack=str_replace_once($needle, $replace2, str_replace_once($needle, $replace, $haystack));
}
return $haystack;
}

Actually, from your description I did not see what you were aiming at ... looking at your code I get an idea now - but still don't get the context. Yes, you can do it this way. But you can also do it much simpler. Remember: the Formatter does exactly this - and it doesn't use a load of extra functions for it. ;-) So: the first question is: can you smply feed the code through the formatter?
$string = Format($string);

should probably do it. If not, please explain the context (and why this doesn't work) and I should be able to give you much simpler code. --JavaWoman

Well, for starters, I want to allow users to put only 'minimal' formatting (bold, italics, underline....for starters) in their message content in wikkaforum....and I wanted to use strip_tags on the input for security. I didn't want full wikka formatting in there tho' (and I certainly never thought that $string=format($string) would work anyways) I thought the above would allow me to replace $this->text with bold_formatting_replace(italic_formatting_replace($this->text)) in the Show_SForum_Threads function (line 17 of that function in wikkaforumfunctions.php) to format the output in the table.

So tell me why my solution doesn't work: we already have a formatter that can do exactly what your functions do. Whatever you feed your functions you can feed the Format() function and get the same result. - I guess still don't get what your problem is... context needed... (BTW, please add one indent when replying to an inline comment!) --JavaWoman

Multiple copies of actions

Not being able to put multiple copies of an action on a page. Can be caused by multiple copies of the same functions being loaded. Solution: have the functions "included" from a separate file using include_once() which stops repeated loading of the functions. Example where implemented: WikkaForum

Only single copies of generated images on a wikka page

In developing my WikkaGrapher action I have it both generating an image and wikka code (that calls an action) that can be placed on a page to place the graph on the page. The action is below (saved as graph.php) and examples of the code are at http://gmbowen.educ.unb.ca/wiki/wakka.php?wakka=Sandbox5 (the code generating interface is at SandBox6). Only the code for the first image is processed for some reason (as can be seen at Sandbox5). Not surprisingly, I'd like users to be able to place more than one graph on a page. Ideas? The graphing engine is at http://www.phpclasses.org/browse/package/1993.html.

<?php
echo '<img src="./scripts/graphmaker.php?'.$code.'> ';
?>

Three problems with that code:

the break tag should be written as (note the forward slash)

just like the break tag the img tag should be closed - but isn't: - you need ' />' at the end (not just '>');

once you do that the main problem causing only one image to appear becomes more visible: the src attribute has only an opening " but not a closing one

Change the code as follows:
<?php
echo '<img src="./scripts/graphmaker.php?'.$code.'" /> ';
?>

BTW, why not use the nice features of class.graphic.php to let the user specify the data it needs as separate action parameters and let the class generate the query string? That would be much more user-friendly. That's what OO is all (well, mostly) about: hiding the complexities... (The form is horribly messy though...)--JavaWoman

you should *blush* again....look at SandBox6 and you'll see I am essentially using his interface....I spent 2 days adapting it so it'd work in wikka & give a preview of the graph. A "save" feature is next (Carlos sent me a copy of his code with that incorporated). And perhaps a series of "if" statements so parameters that are blank are not added onto the string -- GmBowen

Yes, I commented on that messy form, didn't I? (I even updated the link to it. ;-)) What I meant is that your action (apparently) isn't using the class interface to generate the query. Which makes the action hard to use. You could still have it accept the $code paramater, but at the same time have it accept the actual parameters the class can use to generate the query, so it's easier to directly create and/or update the action as embedded in a page. --JavaWoman

Well, I couldn't use his interface directly in wikka because it was non-compatible. But I'm generating his code in almost exactly the same way he did (but w/o java scripts), I'm just using post instead of get. In addition, and I'm sure you'll :) at this, I removed the code that was non-compliant (I had a computer science major looking over my shoulder at one point when I was working on this who pointed out what the compliance problem was). It's quite possible that I'm missing your point here, because I do think I'm doing what you're saying I'm not. Hmmmm.... --GmBowen

How is it not compatible? A class is about the easiest to integrate, I would think. Anyway, show us your action code then so we can see what you are actually doing... --JavaWoman

Now at GraphMaker. His class had embedded formatting all over the place that threw-off wikka....I'm not sure it's a "true" class in the sense of what one of those is (easily embeddable)....it's more like a single-script standalone program.--GmBowen

Mike, it's definitely a valid class, but the html() method is producing a whole page rather than just body content, so you'd need to subclass the class and override the html() method at least. That makes it somewhat harder to use in an application like Wikka, or anything that needs body content only instead of a whole page, but it doesn't mean you can't use it. (The html() method should be refactored though, so it uses a body() method to only generate that part.) Like I said, if you want to use classes, learn how to use classes - sorry. It's the way you are using the file in this context that is causing the problems; it comes with a bunch of examples how to use it - have you tried any of those before even trying to integrate with Wikka? I'd advise you to do that sso you get a feel for how to interface with the class in general, and what it's capable of. --JavaWoman

I could tell it was something with the closing tags (by looking at properties there were things at the end of the code that shouldn't be) but I couldn't figure out what. I tried multiple things, and obviously one resulted in the loss of the end '>'. Why does it have to be '/>' and not just '>'?? (there are vagaries to php that vary from html that I'm not clear on). Thanks JW. Works like a charm now.

Because the html-syntax is <tag></tag> (opening tag - closing tag). There was (and is) no </image> or , and it wasn't necessary in older html-standards, so they defined the form <tag /> for this cases, which opens and closes the tag. --NilsLindenberg

Hmmm, okay. I'll have to work at remembering that...ugh. Thanks Nils. (Now off to bed). -- GmBowen

Actually there is a closing tag for every opening tag in XHTML, so </img> exists, and so does . And in XHTML every tag needs to be closed - which implies that every tag also has a closing tag. However when a tag is empty, you can "shortcut-close" it by ending the tag with '<tag/>' instead of closing it with '<tag></tag>'. That's less to type - but an additional advantage is that some browsers (still) don't support the "full" form but do support the "shortcut" form - especially if you use "compatibilty mode" by putting a space before the slash: <tag />. The latter form is what we use in Wikka , to ensure compatibilty with many browsers. --JavaWoman

Another note: it's probably wise not to have the action accept the $code value blindly; at the very least first build the URL and then URL-encode it to prevent any attacks. Without that, the code is a security risk. (Isn't it surprising how many problems there can be with a single short line of code? ;-)) --JavaWoman

I need more guidance on this I'm afraid (my non-programming background leaping to the fore ;-) )....do you mean do a urlencode($code) in the graph.php file before the "<img src" statement, or alter the output from graphentry.php somehow, or process it through urlencode before being generated by graphentry.php? (these files now at GraphMaker) -- GmBowen

No I mean first build the full URL to be used for the src attribute (first part concatenated with $code), then urlencode() that, then use the result for the img src attribute. The $code is not necessarily generated by the class (you don't know that it is!) - it's accepted blindly by this action without checking.

Okay. I tried this...

$url="./scripts/graphmaker.php?".$code;

$url=urlencode($url);

and then echoed it, and it didn't work. So I played around some and found that even if I entered http://gmbowen.educ.unb.ca/wiki%2Fscripts%2Fgraphmaker.php (with the / replaced with % 2 F) then it didn't work. No surprise then that the urlencoded output didn't work. So, I encoded and then decoded it and that seemed to solve the problem (and, I'm assuming, the security issue). Is this acceptable?

Exactly what do you mean by "didn't work"? What happens when you use a URL-encoded URL for the img src attribute? --JavaWoman

I mean I got a little box with a red x on the wiki page. I played with it lots in the graph.php file and only got the same. So I echoed the code out and it looked fine (both before and after the urlencode was done) so I placed the imgsrc reference in the URL bar....still nothing...didn't generate a graph (or anything). So I took only the http://gmbowen.educ.unb.ca/wiki%2Fscripts%2Fgraphmaker.php bit and still nothing was generated....it should have given me the graph form at least. So, I tried replacing more and more of the %2F's with a slash (in the URL bar) and when they were all replaced THEN it generated the graph form (which my class has been changed to do by default). So I went to php.net and looked to see if there was a way to urlunencode & found there was. So I changed the line (urlencode($code)) (which was generating encoded img src reference to (urldecode(urlencode($code))) and it worked just fine. I subsequently changed it to (urldecode(urlencode(strip_tags($code)))) so that it wasn't possible to put tags into what was being passed at all and that generated graphs too. Because of both striptags and the urlencoding I think I've addressed your concern because urldecoding shouldn't affect the effect of urlencoding should id?

Well, urlencoding a URL and then immediately decoding it before passing it on, just gives you back the original, so that's no security at all. :) Just using strip_tags() on the $code parameter would give a reasonable protection though. I'll have to play with the class myself to see why it doesn't work with an encoded URL - it should, I think. --JavaWoman

The problem might be the server. It doesn't recognize http://gmbowen.educ.unb.ca/wiki%2Fscripts%2F either...so clearly not a problem with the class. Weird. --GmBowen

Hmm - that URL gives me a 404 error: "The requested URL /wiki/scripts/ was not found on this server." Clearly is is interpreting the %2F correctly as a / . --JavaWoman

But if I just copy that line, try it....it doesn't work. If I then edit the url bar and replace %2F with / then it does.

Copy the encoded URL is just what I did, and what generates the 404. Must be your browser that's having a problem with it, I think; try Firefox! (I must be tired...) Indeed, if I replace %2F by / it does work, and I get a directory listing (oops, another security hole); but actually, an encoded URL should be used within HTML only; the browser then takes care of sending the correct request to the server. IOW, if you use it as the href attribute of an a tag, it should work, but not when you paste it into the browser's address bar. --JavaWoman

I was accessing the graph class directly to see how it looked/worked while I was developing the wikkagrapher, that's why that dir is accessible. I've noticed in the past that some servers you can send encoded statements to in the url bar and it works, and others not. What you say is interesting tho'...I wonder why the encoded stuff isn't working in this case because with the usage you describe it should.

Well, actually I think it should work from the address bar, too. (yaaawwn - it's late; can't quite remember now.) Strange, though. What server are you using?

A linux red-hat variant intended to be a small to medium business server called sme-server (www.contribs.org) that's a much modded version of Redhat 7.2. It's got secure information bays (individual root directories essentially) etc. that variables won't pass across and are not cross-browsable for instance. Plus bays are individually controllable for running scripts, access etc. -- mike

BTW, thanks for your help on this. You know a million resources...any idea where I'd find code that would allow me to parse the action statement in the textarea box back IN to variables/values? (then a user could re-edit the graph parameters using the form by placing it in the textarea box and "submitting" it).

Have a look at what I conconcted on your GraphMaker page ;-) Not quite what you're asking, but it could easily be extended with a custom form. --JavaWoman

ya, I'll look at it tomorrow. Got some course-related web developing to do for tomorrow. -- m

I've looked at the code & it works nicely....I see what you're talking about now re: parameters vs. a string.....I'll first work at re-doing the form output so that it generates that sort of parameter output. --m

Unresolvable Issues

Double-Click Edit

Is there any way to insert code into an action that disables the double-click editing on a page? I thought I saw something on this site but cannot find it anymore.

Not per page, and not as an action - but each registered user can enable/disable it in their own user settings. --JavaWoman

Rats. I was hoping for a workaround. - m

CategoryDevelopment

Wikka : ProgrammingHelp

Revision [4529]