Mailman 3 December 2004 - Twisted-web

nevow.liveevil question (dynamically adding a link with its own handler)
by David Moore 21 Dec '04

21 Dec '04

I'm working on a project[1] which will require very dynamic webpages. I'm very excited to discover nevow.liveevil (I'd rather program in Python than JavaScript). But I'm having trouble dynamically adding a link which can then call further Python code. My code.... --------------------------------------------------------------------- #!/usr/bin/python from nevow import rend from nevow import loaders from nevow import tags from nevow import liveevil from twisted.internet import reactor def adder(client): # newLink = loaders.stan(tags.a(href="#")["Nothing"]) newLink = loaders.stan(tags.a(href="#", onclick=liveevil.handler(adder))["AddAgain"]) client.append('content', newLink) mycontent = loaders.stan( tags.html[ tags.head[liveevil.glue], tags.body[ tags.a(href="#", onclick=liveevil.handler(adder))["Add"], tags.div(id="content"), ] ]) mypage = rend.Page(docFactory=mycontent) mypage.addSlash = True mysite = liveevil.LiveSite(mypage) reactor.listenTCP(8080, mysite) reactor.run() --------------------------------------------------------------------- When I click on the Add link I get --------------------------------------------------------------------- Traceback (most recent call last): File "br.py", line 28, in ? reactor.run() File "/usr/lib/python2.3/site-packages/twisted/internet/default.py", line 126, in run self.mainLoop() File "/usr/lib/python2.3/site-packages/twisted/internet/default.py", line 134, in mainLoop self.runUntilCurrent() --- <exception caught here> --- File "/usr/lib/python2.3/site-packages/twisted/internet/base.py", line 423, in runUntilCurrent call.func(*call.args, **call.kw) File "/usr/lib/python2.3/site-packages/Nevow/nevow/liveevil.py", line 101, in handleInput self.events.publish(identifier, *(self, ) + args) File "/usr/lib/python2.3/site-packages/Nevow/nevow/events.py", line 41, in publish sub(*args) File "br.py", line 12, in adder client.append('content', newLink) File "/usr/lib/python2.3/site-packages/Nevow/nevow/liveevil.py", line 130, in append client.sendScript( File "/usr/lib/python2.3/site-packages/Nevow/nevow/liveevil.py", line 112, in flt fl = flatten(stan, ctx=ctx) File "/usr/lib/python2.3/site-packages/Nevow/nevow/flat/ten.py", line 146, in flatten list(iterflatten(stan, ctx, result.append)) File "/usr/lib/python2.3/site-packages/Nevow/nevow/flat/ten.py", line 104, in iterflatten for item in gen: File "/usr/lib/python2.3/site-packages/Nevow/nevow/flat/flatstan.py", line 84, in TagSerializer yield serialize(toBeRenderedBy, context) File "/usr/lib/python2.3/site-packages/Nevow/nevow/flat/ten.py", line 91, in serialize return partialflatten(context, obj) File "/usr/lib/python2.3/site-packages/Nevow/nevow/flat/ten.py", line 82, in partialflatten return flattener(obj, context) File "/usr/lib/python2.3/site-packages/Nevow/nevow/flat/flatstan.py", line 168, in FunctionSerializer data = convertToData(context.locate(IData), context) File "/usr/lib/python2.3/site-packages/Nevow/nevow/context.py", line 100, in locate return self.parent.locate(interface, depth) File "/usr/lib/python2.3/site-packages/Nevow/nevow/context.py", line 203, in locate return WebContext.locate(self, interface, depth) File "/usr/lib/python2.3/site-packages/Nevow/nevow/context.py", line 99, in locate raise KeyError, "Interface %s was not remembered." % key exceptions.KeyError: 'Interface nevow.inevow.IData was not remembered.' --------------------------------------------------------------------- I don't get this problem if I replace the AddAnother link with the Nothing link (as commented out in the code.) Is this expected-behaviour, a bug in my code, or a bug in liveevil???? Any help would be greatly appreciated. Thanks! David. [1] https://eduforge.org/projects/exe E-learning XML Editor -- (o_ David Moore //\ LinuxSoftware - Custom software development for Linux! V_/_ http://www.linuxsoftware.co.nz

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loaders.xmlstr versus loader.xmlfile
by Michael Wilson 21 Dec '04

21 Dec '04

If I have a form definition like the one in customform.py: FORM = loaders.xmlstr( """<?xml version="1.0"?> <div id="centerContent"> <form xmlns:n="http://nevow.com/ns/nevow/0.1" n:pattern="freeform-form">  <n:attr name="action"><n:slot name="form-action"/></n:attr> .... Shouldn't I be able to put it into a file and replace "loaders.xmlstr(...)' with "loaders.xmlfile(...)" and have it act exactly the same? I thought so to, but when I do that, the form now acts like a formless -- all of the information in FORM above is ignored. I thought it was a problem with the file name, so I tried .html, .xml, .xhtml, and they all produced the same results. I've looked at the docs and the code, and I can't see why it might be doing this. Thanks!

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Twisted PostgreSQL Library
by J Turner 18 Dec '04

18 Dec '04

Hello list, I've been working on and off over the last few weeks on a twisted-based pgsql library--driven by my desire to keep threads completely out of my apps! It's come together at this point into something worth releasing.. you can find it here: http://www.jamwt.com/pgasync/ It's DB API 2.0 compliant, and it has a adbapi wrapper as well for existing implementations. I could rattle off all the details here, but I've already done that like three times in the last few hours (freshmeat, home page, README, blah blah blah). So far, in my informal benchmarks performance and scalability look to be very promising vs. adbapi/threads. Anyway, feel free to check it out, and I'd love to get feedback, suggestions (and certainly bug reports). Thanks, - Jamie Turner

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Rendering error messages
by Michael Wilson 17 Dec '04

17 Dec '04

I have a form where the inputs various values, which I then check for validity. If there are errors, I'd like to re-display the form, with errors. >From the examples, I see how to use pasting to get the error into the form: .... <td>School name:</td> <td>  </td> <td><input type="text" name="name" /></td> <td><nevow:slot name="nameError">error</nevow:slot></td> .... def render_aPasting(self, context, data): context.tag.fillSlots('nameError', self.nameError) ---- That works great. The problem is, I initialize self.nameError in __init__: self.nameError = '' And then set it in the formless autocall if there is an error: ----- if self.schoolDb.exists( name ): self.nameError = 'School already exists!' return ---- The problem is that when the page is re-rendered, __init__ is being called again, which means the errors get cleared. My instinct is that maybe I should use session variables, but before I got an do that I wanted to make sure there wasn't another, more correct way to do this. Thanks!

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Re: [Nevow-commits] r952 - adding documentation for inevow.ISession
by Matt Goodall 16 Dec '04

16 Dec '04

On Wed, 2004-12-15 at 14:03 -0500, dialtone(a)divmod.net wrote: > Author: dialtone > Date: Wed Dec 15 14:03:44 2004 > New Revision: 952 > > Modified: > trunk/nevow/inevow.py > Log: > adding documentation for inevow.ISession Great stuff! I'm just about to eat dinner so this is a bit rushed ... I think we should differentiate between a typical session and a guard/cred session. Most applications don't (and probably shouldn't) care about the cred side of things except for some way to locate the avatar. It also looks like there's a good case for extracting a IComponentized interface. Perhaps that's already been done for twisted 2? So, how about a class hierarchy more like: class IComponentized(Interface): pass class ISession(IComponentized): pass class I(Guard|Cred)Session(ISession): pass >From the (newly) current ISession class ... setComponent, getComponent, unsetComponent, removeComponent would be IComponentized methods, although unsetComponent looks unnecessary unless it's the opposite of setComponent and there should also be an addComponent. getLoggedInRoot, resourceForPortal, setResourceForPortal, portalLogout, are IGuardSession methods. However, getLoggedInRoot sounds strange, and resourceForPortal and setResourceForPortal sound like guard implementation. setLifetime, notifyOnExpire, expire, touch, checkExpired are ISession methods. However, IIRC checkExpired is an implementation method used as the timed callback to automatically expire individual sessions. Finally, of the attributes listed in the class docstring, I think only uid and guard are part of the interface and guard should be part of IGuardSession. Hope that makes sense and that I didn't miss anything. What do others think? Cheers, Matt > > Modified: trunk/nevow/inevow.py > ============================================================================== > --- trunk/nevow/inevow.py (original) > +++ trunk/nevow/inevow.py Wed Dec 15 14:03:44 2004 > @@ -378,13 +378,94 @@ > """A web session > > You can locate a Session object to represent a unique web session using > - ctx.locate(ISession). This default session implementation uses cookies to > + ISession(ctx). This default session implementation uses cookies to > store a session identifier in the user's browser. > - > + > + guard: SessionWrapper object > + uid: Session uid > + expireCallbacks: callbacks for expiration event > + checkExpiredID > + portals: portals in which the session is logged in > + > TODO: Need better docs; what's a session and why and how do you use it > """ > - > + def getLoggedInRoot(self): > + """Get the most-recently-logged-in avatar. > + """ > + > + def resourceForPortal(self, port): > + """Gather the resource set for the portal port > + """ > + > + def setResourceForPortal(self, rsrc, port, logout): > + """Set returned resource when asking for something in portal port > + logout is called when logged out from the resource > + """ > + > + def portalLogout(self, port): > + """Logout from portal port > + """ > + > + def setLifetime(self, lifetime): > + """Set the approximate lifetime of this session, in seconds. > + > + This is highly imprecise, but it allows you to set some general > + parameters about when this session will expire. A callback will be > + scheduled each 'lifetime' seconds, and if I have not been 'touch()'ed > + in half a lifetime, I will be immediately expired. > + > + If you need to change the lifetime of all the sessions change sessionsLifeTime > + attribute in class guard.SessionWrapper > + """ > + > + def notifyOnExpire(self, callback): > + """Call this callback when the session expires or logs out. > + """ > + > + def expire(self): > + """Expire/logout of the session. > + """ > + > + def touch(self): > + """Refresh the session > + """ > + > + def checkExpired(self): > + """ Check expiration state for the session > + """ > + > + def setComponent(self): > + """ > + Add a component to me, for all appropriate interfaces. > + """ > + > + def getComponent(self, interface, registry=None, default=None): > + """Create or retrieve an adapter for the given interface. > + > + If such an adapter has already been created, retrieve it from the cache > + that this instance keeps of all its adapters. Adapters created through > + this mechanism may safely store system-specific state. > + > + If you want to register an adapter that will be created through > + getComponent, but you don't require (or don't want) your adapter to be > + cached and kept alive for the lifetime of this Componentized object, > + set the attribute 'temporaryAdapter' to True on your adapter class. > + > + If you want to automatically register an adapter for all appropriate > + interfaces (with addComponent), set the attribute 'multiComponent' to > + True on your adapter class. > + """ > + > + def unsetComponent(self, interfaceClass): > + """Remove my component specified by the given interface class.""" > + > + def removeComponent(self, component): > + """ > + Remove the given component from me entirely, for all interfaces for which > + it has been registered. > > + @return: a list of the interfaces that were removed. > + """ > > class IRemainingSegments(compy.Interface): > """During the URL traversal process, requesting this from the context > > _______________________________________________ > Nevow-commits mailing list > Nevow-commits(a)divmod.org > http://divmod.org/users/mailman.twistd/listinfo/nevow-commits

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Nevow: How to use sessions?
by Mohamed Lrhazi 15 Dec '04

15 Dec '04

Hello all, Can someone give a helloworld example of how to store and retrieve objects specific to a session ? maybe a counter example. The objects would need to be destroyed automatically when the session expires. In the examples I see things like: def setupSession(self, ctx): #need to place the user, usermanager in the session inevow.ISession(ctx).setComponent(ICurrentUser, self.user) inevow.ISession(ctx).setComponent(IUserManager, self.userManager) and self.userManager = request.session.getComponent(IUserManager) Can I just do that to store any object? do I have to create an interface for it? When I looked for more in the source all I found was: class ISession(compy.Interface): """A web session You can locate a Session object to represent a unique web session using ctx.locate(ISession). This default session implementation uses cookies to store a session identifier in the user's browser. TODO: Need better docs; what's a session and why and how do you use it """ Thanks a lot. Mohamed~

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Accessing ISession from formless autocallable
by Michael Wilson 15 Dec '04

15 Dec '04

An autocall gets (self, request...), but not context. If I want to set session variables (as discussed in the previous exchange), how can I do it without ctx? Thanks!

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newbie: Stan syntax question
by Mohamed Lrhazi 15 Dec '04

15 Dec '04

Hello again, I just spent sometime trying to figure this one out by myself... but could not :( How do you build a table dynamically, or any other stan structure for that matter? Here is what I am trying to do: def render_tasks(self, context, data): attrs = ['task_id', 'task', 'arguments'] mytrs=T.tr for row in self.tasklist: for attr in attrs: mytrs += T.td[row.get(attr)] header_tr=T.tr[T.th["ID"],T.th["Task"],T.th["Arguments"]] mytable=T.table[header_tr,(mytrs)] return context.tag[mytable] This gives: exceptions.TypeError: cannot concatenate 'str' and 'Tag' objects I tried many other different ways to no avail.... I guess my question is how do you build the document dynamically, adding, inserting into it? Sorry for my newbie questions... Mohamed~

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maxlength input with formless
by Andrea Arcangeli 10 Dec '04

10 Dec '04

How can I define a maxlength for my input fields in a form? Do I need to modify the formless module or is there a trick? Wouldn't be much simpler if the attributes passed as last parameter to annotate.Typed would be rendered without any parsing inside the input block? Or can I use the css to set the maxlength based on the id? (I tried that, but I couldn't find a way to do it with the css yet ;) Otherwise another way that would be fine, is if I can write some code to edit myself the result of webform.renderForms() before returning it from the "def render_form()". Thanks.

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Accessing CSS Style sheets and the like
by Michael Wilson 07 Dec '04

07 Dec '04

Hi I'm a nevow newbie, and I have a quick question. Imagine I have a .xhtml like this: <?xml version="1.0"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:nevow="http://nevow.com/ns/nevow/0.1"> <head> <title>Main page</title> <style type="text/css" media="screen">@import "styles-site-nl.css";</style> </head> <body> <div id="banner"> .... The import for "styles-site-nl.css" goes to Twisted/Nevow, who then looks for a styles-site-nl.css object, which exists on disk, but of course there's no method for it anywhere. Of course I can make this a straight http://... reference, but that seems a little clunky. Is there a way to tell Newvow/Twisted "All references beginning with (say) "blatz/" should just be fetched as files? Thanks! Michael Wilson http://www.tzec-maun.com

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