Revision [4577]
This is an old revision of ProgrammingHelp made by GmBowen on 2005-01-13 01:48:09.
Programming Help
See also:
Many people work at developing various aspects of code for wikka and yet we often struggle for hours, or even days, to solve programming problems that others in the wikka community know the answer to. Even more of an issue, sometimes coding problems aren't rectified until after initial code releases and feedback from other members lead to new code being posted (which means that the old code might now be running on others' wikka implementations) because the initial developer could not figure out how to solve a problem. To reduce these problems, this page is intended for people to be able to pose programming issues they've encountered and have the opportunity to draw on the knowledge of others' in our community as to how to resolve those issues. There are two sections...."Issues Needing assistance" & "Solved Issues". When a user has either solved an issue on their own that they've posted, or received help on the issue that satisfactorily addresses it, then the solution should be posted and it should be moved from the first to the second category.
Issues Needing Assistance
Resolved Issues
Replace
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 withFinding 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="<strong>";
$replace2="</strong>";
while ($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="<em>";
$replace2="</em>";
while ($counter<$count)
{
$counter++;
$haystack=str_replace_once($needle, $replace2, str_replace_once($needle, $replace, $haystack));
}
return $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="<strong>";
$replace2="</strong>";
while ($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="<em>";
$replace2="</em>";
while ($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... If you want to ignore any other formatting, just strip it before feeding the Format() function. (BTW, please add one indent when replying to an inline comment!) --JavaWoman
- Uh, it could just be my lack of understanding re: functions. Can I call wikka functions "in" other functions that I've written and included in a script?
- Sure, you can. How you do that depends no the context (scope) from where you're calling. Have a look at how actions call Wikka functions, and how the Formatter (wakka.php) calls Wikka functions for instance. --JavaWoman
- I didn't know that....I'll give it a try. Then I guess I just strip un-wanted wikka formatting out using a replace? Okay, if I can get the first bit working I'll try that too. (A good exercise for me anyways "writing" a completely new function....those above are the first I've done from scratch...learned ya GOTTA put a "return" statement in...took AGES to figure that out). I'll get back to you if I cannot make this approach work. --M
- Hmm, okay, using format($this->text) on line 17 of the Show_SForum_Threads function doesn't work at all (the output is only partial and all wiki headers/footers etc disappear), but, sigh, my functions don't work either if I use them in the same place. I don't have time to play with them more today to figure out why.....they work on strings "independent" of wikka (if I hard code a string into a file with just them in it and process the string) the output looks correct (see http://gmbowen.educ.unb.ca/test2/rename.php)...but see the note there...maybe there's a problem with output (like I have to do something for the html tags to be picked up... if you go to the root of that directory you can get to a copy of the file with a txt extension you can download). Anyhow, I've mucked with it and calling the wikka function (I looked at how actions & the wikka formatter do it as you suggested) and tried $this->format($this->text) instead on line 17 and that didn't work either....same output format as above using $this->format($this->text) as format($this->text). -m
- okay, I played with it more. Yup, I can use wikka formatter BUT I have to declare global $wakka; (darn those globals) in the function I'm using it in and then use $wakka->format($this->text);. I still have to strip out other wikka tags (I'll keep underlining, bold, italics, center, highlight text, strikethrough & lists) & I don't want actions to work...but I'll continue to play with this. Thanks for the help so far. -- mike
- Okay, I came up with the following to go into Show_SForum_Threads function....it strips out header code etc, and converts }} and {{ to |.| (I wanted to de-activate action code, but not use ||)
$printtext = (stripslashes($row['for_text']));
$brackets = Array ('/{{/i', '/}}/i');
$changeto = '|.|';
$printtext = preg_replace($brackets, $changeto, $printtext);
$remove = array("#%", "======", "=====", "====", "===", "==", "[[", "]]", "||", "
", "$brackets = Array ('/{{/i', '/}}/i');
$changeto = '|.|';
$printtext = preg_replace($brackets, $changeto, $printtext);
$remove = array("#%", "======", "=====", "====", "===", "==", "[[", "]]", "||", "
", "
", "
");
tags, and I've found no way of removing double quotes. Any ideas? -- mike
==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 [[http://gmbowen.educ.unb.ca/wiki/wakka.php?wakka=Sandbox6 SandBox6]]). Only the code for the first image is processed for some reason (as can be seen at [[http://gmbowen.educ.unb.ca/wiki/wakka.php?wakka=Sandbox5 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)
'; ?>%% ~& 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)
'; ?>%% BTW, why not use the nice features of [[http://www.phpclasses.org/browse/package/1993.html 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 [[http://gmbowen.educ.unb.ca/wiki/wakka.php?wakka=Sandbox6 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
$url="./scripts/graphmaker.php?".$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?
$printtext = str_replace($remove, , $printtext);
$printtext = $wakka->format($printtext);
%%
But, it doesn't actually strip out the
or '; ?>%% ~& 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)
'; ?>%% BTW, why not use the nice features of [[http://www.phpclasses.org/browse/package/1993.html 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 [[http://gmbowen.educ.unb.ca/wiki/wakka.php?wakka=Sandbox6 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
- 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
CategoryDevelopment
