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• Detach current session and attach to another session, done with one script, can I?

  - by Jimm Chen

  After reading the vague official doc of GNU screen( http://www.gnu.org/software/screen/manual/screen.html ) and asking quite some questions at this site. I still cannot figure out how to accomplish such a task with a shell script. This task costs some words to describe. Assume I'm using PuTTY to telnet into my Linux server. ?STEP 1? Launch 2 telnet connections . From putty window 1 (PTWIN1),telnet into Linux Bash shell, execute screen -RR to launch a screen session, and get session name 21385.pts-4.linux-ic37 . From putty window 2 (PTWIN2), do that same as in PTWIN1, but this time, I get session name 22041.pts-9.linux-ic37 . Now, we have two screen sessions running simultaneously. We can check this: $ screen -ls There are screens on: 22041.pts-9.linux-ic37 (Attached) 21385.pts-4.linux-ic37 (Attached) 2 Sockets in /var/run/uscreens/S-chj2. ?STEP 2? Assume that for some reason, PTWIN1's TCP connection is lost abnormally(but server doesn't know that), and an urgent work is pending on session 21385 and I want to quickly regain control of it. Fortunately, we know the 21385 session is still there, so, I want to have PTWIN2 attach to session 21385. Because I hate to remember the esoteric screen option all the time, so I decide to write a script called sttach. I hope that sttach 21385.pts-4.linux-ic37 can let me attach to session 21385(for PTWIN2). Now, let's say sttach works well and I take control of 21385 on PTWIN2. ?STEP 3? Some minutes later. I want to go back to work on session 22041. Here, please allow me to have PTWIN2 remain associated with session 21385. What I would like to do is to launch another putty window (PTWIN3), telnet into server, and execute sttach 22041.pts-9.linux-ic37 in hope that I can resume session 22041 on PTWIN3 . You can see the benefit of sttach: as long as I know the target session name, I can call it to have my PuTTY window switch to that session, regardless whether the target session is "(Attached)" or "(Detached)", and regardless whether the running context is inside a screen session or not. Now the question: How to write the (Bash) script sttach? I mean, run screen with appropriate options in sttach to accomplish the goal. Waiting for your kind answer. Thank you. My previous questions regarding GNU screen: GNU screen, how to get current sessionname programmatically Is it possible to change GNU screen session name after created? How do I know I'm running inside a linux "screen" or not? My env: openSUSE Linux 11.3, GNU screen 4.00.03 (FAU) 23-Oct-06

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• ADExplorer, how to search with "distinguishedName contains" condition?

  - by Jimm Chen

  I'm using ADExplorer 1.42 from Microsoft. I'm not very versed at this program so please kindly help me out with a search-related problem. Right click on a node(e.g., CN=NlscanStaff) and select Search Container... , with default search attributes, I can see all objects inside NlscanStaff listed as result. Note that there is a CN=CHJTEST object listed. Now, my question is, how to search for CHJTEST specifically? I tried search condition: Attribute : distinguishedName Relation : contains Value : CN=CHJTEST Click Add , then Search . But no result. Can someone tell me what's going wrong? Thanks.

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• Some Windows AD user property cannot be changed by AD user himself, what controls it?

  - by Jimm Chen

  I'm curious with a question I find. An Windows Active Directory user can change his own telephone number, street address etc, but can NOT change his own email-address registered on the AD. Using Python+pywin32 I can also verify this behavior. When trying to change own EmailAddress, I got error General access denied error . I'd like to know where in the AD this allow/deny behavior is defined. Thank you.

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• Exchange 2010 Mail Enabled Public Folder Unable to Recieve External (anon) e-mail.

  - by Alex

  Hello All, I am having issues with my "Public Folders" mail enabled folders receiving e-mails from external senders. The folder is setup with three Accepted Domains (names changed for privacy reasons): 1 - domain1.com (primary & Authoritative) 2 - domain2.com (Authoritative) 3 - domain3.com (Authoritative) When someone attempts to send an e-mail to [email protected] from inside the organization, the e-mail is received and placed in the appropriate folder. However, when someone tries to send an e-mail from outside the organization (such as a gmail account), the following error message is received: "Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 554 554 Recipient address rejected: User unknown (state 14)." When I try to send an e-mail to the same folder, using the same e-mail address above ([email protected]), but with domain2.com instead of domain3.com, it works as intended (both internal & external). I have checked, double checked, and triple checked my DNS settings comparing those from domain2 & domain3 with them both appearing identical. I have tried recreating the folders in question with the same results. I have also ran Get-PublicFolderClientPermission "\Web Programs\folder" with the following results for user anonymous: RunspaceId : 5ff99653-a8c3-4619-8eeb-abc723dc908b Identity : \Web Programs\folder User : Anonymous AccessRights : {CreateItems} Domain2.com & Domain3.com are duplicates of each other, but only domain2.com works as intended. All other exchange functions are functioning properly. If anyone out there has any suggestions, I would love to hear them. I've just hit a brick wall. Thanks for all your help in advance! --Alex

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• Forward Apache to Django dev server

  - by Alex Jillard

  I'm trying to get apache to forward all requests on port 80 to 127.0.0.1:8000, which is where the django dev server runs. I think I have it forwarding properly, but there must be an issue with 127.0.0.1:8000 not being run by apache? I'm running the django dev server in an ubuntu vmware instance, and I'd other people in the office to see the apps in development without having to promote anything to our actual dev/staging servers. Right now the virtual machine picks up an IP for itself, and when I point a browser to that url with the defualt apache config, I get the default apache page. I've since changed the httpd.conf file to the following to try and get it to forward the requests to the django dev server: ServerName localhost <Proxy *> Order deny,allow Allow from all </Proxy> <VirtualHost *> ServerName localhost ServerAdmin [email protected] ProxyRequests off ProxyPass * http://127.0.0.1:8000 </VirtualHost> All I get are 404s with this, and in error.log I get the following (192.168.1.101 is the IP of my computer 192.168.1.142 is the IP of the virtual machine): [Mon Mar 08 08:42:30 2010] [error] [client 192.168.1.101] File does not exist: /htdocs

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• Limit vsftpd upload to a given set of file-names

  - by Chen Levy

  I need to configure an anonymous ftp with upload. Given this requirement I try to lock this server down to the bear minimum. One of the restrictions I wish to impose is to enable the upload of only a given set of file-names. I tried to disallow write permission to the upload folder, and put in it some empty files with write permission: /var/ftp/ [root.root] [drwxr-xr-x] |-- upload/ [root.root] [drwxr-xr-x] | |-- upfile1 [ftp.ftp] [--w-------] | `-- upfile2 [ftp.ftp] [--w-------] `-- download/ [root.root] [drwxr-xr-x] `-- ... But this approach didn't work because when I tried to upload upfile1, it tried to delete and create a new file in its' place, and there is no permissions for that. Is there a way to make this work, or perhaps use a different approach like abusing the deny_file option?

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• How can user change the jre parameter values after the exe is generated in Launch4j?

  - by Wing C. Chen

  Is it possible to change the jre parameter values after the exe file is generated through Launch4j? The ideal scenario is like this: The default parameter values are applied when the program is started. However, when the user wants to change some jre parameter values, he goes to a .ini file, MyProgram.ini for example, changes the values there, and the new values will be applied next time the program is started. I think eclipse uses the same way for its memory and some other parameter settings.

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• Recovering data from mangodb raw files

  - by Jin Chen

  we use mongodb for our database and set the replset(two servers), but we mistakenly deleted some raw files that under /path/to/dbdata on both servers, after we used tool to get back the deleted files(we ran the extundelete on both server and mix the result together), like database.1, database.2 etc. we could not start the mongod, it raised the following error when starting mongod or executing mongodump, here is the console output: root@mongod:/opt/mongodb# mongodump --repair --dbpath /opt/mongodb -d database_production Thu Aug 21 16:22:43.258 [tools] warning: repair is a work in progress Thu Aug 21 16:22:43.258 [tools] going to try and recover data from: database_production Thu Aug 21 16:22:43.262 [tools] Assertion failure isOk() src/mongo/db/pdfile.h 392 0xde1b01 0xda42fd 0x8ae325 0x8ac492 0x8bd8e0 0x8c1c51 0x80e345 0x80e607 0x80e6a4 0x6db92a 0x6dc1ff 0x6e0db9 0xd9e45e 0x6ccdc7 0x7f499d856ead 0x6ccc29 mongodump(_ZN5mongo15printStackTraceERSo+0x21) [0xde1b01] mongodump(_ZN5mongo12verifyFailedEPKcS1_j+0xfd) [0xda42fd] mongodump(_ZNK5mongo7Forward4nextERKNS_7DiskLocE+0x1a5) [0x8ae325] mongodump(_ZN5mongo11BasicCursor7advanceEv+0x82) [0x8ac492] mongodump(_ZN5mongo8Database19clearTmpCollectionsEv+0x160) [0x8bd8e0] mongodump(_ZN5mongo14DatabaseHolder11getOrCreateERKSsS2_Rb+0x7b1) [0x8c1c51] mongodump(_ZN5mongo6Client7Context11_finishInitEv+0x65) [0x80e345] mongodump(_ZN5mongo6Client7ContextC1ERKSsS3_b+0x87) [0x80e607] mongodump(ZN5mongo6Client12WriteContextC1ERKSsS3+0x54) [0x80e6a4] mongodump(_ZN4Dump7_repairESs+0x3a) [0x6db92a] mongodump(_ZN4Dump6repairEv+0x2df) [0x6dc1ff] mongodump(_ZN4Dump3runEv+0x1b9) [0x6e0db9] mongodump(_ZN5mongo4Tool4mainEiPPc+0x13de) [0xd9e45e] mongodump(main+0x37) [0x6ccdc7] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xfd) [0x7f499d856ead] mongodump(__gxx_personality_v0+0x471) [0x6ccc29] assertion: 0 assertion src/mongo/db/pdfile.h:392 Thu Aug 21 16:22:43.271 dbexit: Thu Aug 21 16:22:43.271 [tools] shutdown: going to close listening sockets... Thu Aug 21 16:22:43.271 [tools] shutdown: going to flush diaglog... Thu Aug 21 16:22:43.271 [tools] shutdown: going to close sockets... Thu Aug 21 16:22:43.272 [tools] shutdown: waiting for fs preallocator... Thu Aug 21 16:22:43.272 [tools] shutdown: closing all files... Thu Aug 21 16:22:43.273 [tools] closeAllFiles() finished Thu Aug 21 16:22:43.273 [tools] shutdown: removing fs lock... Thu Aug 21 16:22:43.273 dbexit: really exiting now my env: 1) Debian 3.2.35-2 x86_64(it's a XEN virtual machine) 2) mongodb 2.4.6 and we did not delete the .0 and .ns files we tried to create a new database with the same name and copy these db.ns and db.2, db.3 to the new db, we still met the same error. is there any way to check the valid of raw .ns and datafiles, and how to recover the database?

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• setting up rhel 5.x RPM build server for mortal users

  - by Chen Levy

  My task is to setup a RHEL 5.x build host, that can build RPMs for mortal users. On RHEL 6.x with rpm version 4.8, I have in /usr/lib/macros: # Path to top of build area. %_topdir %{getenv:HOME}/rpmbuild On RHEL 5.x with rpm version 4.4, the %{getevn:HOME} is not available. I know that I can use /home/someuser/.rpmmacros: %_topdir /home/someuser/rpmbuild and this will work for that user, however I don't want to do this for every user separately. Moreover, since .rpmmacro will not expand ${HOME} or ~ I suspect it is unsafe to use those. This in turn make /etc/skel unstable for this task (or so I suspect). So in short, my question is: How to setup RHEL 5.x host that allow all users to build RPM packages in their home directory?

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• Can ZenOSS integrate Ganglia smoothly?

  - by chen

  I like Ganglia for its Gmetric function, and I like its multi-layer capability. But Ganglia does not have healthiness check, alerting and etc. for the server monitor functionality. So it would be great to bring this two species together. Sure, we can install Ganglia, and then install ZenOSS. But is there a plugin or something that can smoothly integrate them together? At least integration at the presentation level. Thanks

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• Any program to help me check whether an ethernet channel can support full-length VLAN packet?

  - by Jimm Chen

  Sometimes, I have to face such a situation that I need to quickly and explicitly know whether a full length VLAN packet can traverse between two RJ45 ports. Yes, I mean 802.1Q ethernet frame with Etype=81 00 (diagram below). What I can do now is: Get two Windows PCs, for each PC, intall Intel Gigabit NIC and Intel specific driver to create a virtual NIC, with VLAN ID=3 assigned. Then connect the two PCs to each of the two RJ45 port. Finally execute ping to generate a full-length ethernet packet. ping -f -l 1472 <dest-IP> This way, I can be sure that the sent packet has the maximum "IP data payload" of 1500 bytes(8 bytes of ICMP header and 1472 bytes of ICMP data). If the ping gets reply, I know that the ethernet channel support full-length VLAN packet. From my experiment, some home switch or broad band routers(e.g. Linksys WRT54G) does not support full-length VLAN packet switching, so only ping -f -l 1468 succeeds. You see, I have to use an expensive Intel NIC to carry on that test, quite inconvenient. You know, for most laptop today, they do not equip an Intel NIC, and, even it is an Intel NIC, Intel VLAN driver, Intel has limitations on the models on which VLAN driver can be installed. So, my question is: Is there a small program that can let me send a full-length VLAN packet without installing a dedicated VLAN driver? Or better, the program has a stock feature that does the very job for my situation. Windows programs preferred, Linux solution welcome. Simpler the program, the better. Thank you.

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• Is there any problem using the ftpd that comes with Kerberos on CentOS?

  - by Chen Levy

  Hello, I need to configure ftpd on a CentOS 5.3 host to allow anonymous ftp (upload and download) from a well defined directory. I wish the setup to be as simple as possible, and to introduce as little new dependencies as possible. Scanning the current server configuration, I found the ftpd server that comes as part of the Kerberos workstation: > rpm -ql krb5-workstation | grep ftpd$ /usr/kerberos/sbin/ftpd Is there any reason I could or should not use this ftp server?

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• GNU screen, how to get current sessionname programmatically

  - by Jimm Chen

  [ This can be considered step 2 of my previous question Is it possible to change GNU screen session name after created? ] Actually, I'd like to write a script that can display current screen session name and change current session name. For example: sren armcross It will change the session name to armcross (ARM gcc cross compiler) and output something like: screen session name changed from '25278.pts-15.linux-ic37' to 'armcross' So, the key question now is how to get current session name. Not only for display the old session name, but according to Is it possible to change GNU screen session name after created? , I have to know it(pass to -d -r) before I can change it to something else. Can we use $STY for current session name? No. $STY will not change after you have changed the session name to a user-defined one. However, for command screen -d -r <oldsessname> -X sessionname armcross should be the user-defined name(if ever defined) instead of $STY, otherwise, screen spouts error "No screen session found." Maybe, there is a verbose way, use screen -list to list all sessions(user-defined name listed), then, match the pid part from $STY against those listed sessions and we will find current session's user-defined name. It should not be so verbose for such a straightforward question. Don't you think so? The -d -D and -r -R options seems to expose too much implementation detail to screen's user. It seems, to rename a session, you have to detach it, then do the rename, then reattach it. Right? My env: opensuse 11.3, GNU screen 4.00.03 (FAU) 23-Oct-06 Thank you.

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• Is there keyboard shortcut to move input focus to the Google Search box?

  - by Chen Jun

  I'm searching on Google a lot. I find it very annoying to move my mouse to the search box and click once so that I can input another search term. I did Googled some time, but no one seems to be annoyed with this, quite unbelievable. I'm using Firefox 8 and Chrome 16, on Windows 7. If you know Atlassian Confluence, you might probably know that pressing / will move input focus to the upper right search box, very convenient for a keyboard shortcut hobbyist . Try it here.

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• Possible to use DRBD on two ESXi virtualized servers?

  - by chen

  I have two servers (attached disks have been set up as hardware RAID1 for disk device level failure resilience). Here is the setup in my mind: 1) Install ESXi on each of the physical server, M1, M2; 2) Start one VM on each of the ESXi virtualized physical server V1, V2; 3) Install the DRDB drivers within V1 and V2. Essentially, this is a "virtualizing machine running DRBD in the VM's instead of bare metal hardware" idea. My question is whether the above setup can achieve the same "networked RAID1" goal that DRDB can achieve in the bare-metal physical machines (http://www.drbd.org/). Thanks. [EDIT] I found this (http://serverfault.com/questions/49305/drbd-experimentation-and-virtualization) is a similar question, but the answer does not seem to be firmative enough for me to follow.

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• How to set specific environment variables for Apache service run on Windows

  - by Jimm Chen

  I'm facing a problem. I use xampp 1.7.7 on Windows which installs a Apache service. I find that I have to some tweak to have all PHP modules load properly. For example, php_ldap.dll cannot be loaded. It is mysterious why it cannot be loaded until I tried to run httpd.exe from command line, which reveals that libsasl.dll cannot be founded. Actually, there exist D:\xampp\php\libsasl.dll but httpd.exe cannot find it. OK. The best way is to add D:\xampp\php to PATH env-var. Now my question is: How do I set a specific PATH value for that specific Apache service but not system wide. -- because I think it is better not to disturb other processes with that extra PATH value. Is there a general way to do that for a specific Windows service? or, is there a Apache specific way to load extra env-var settings from some specific configuration files?

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• Google Apps, SPF, softfail problem (validates with validation tools, but still softfails otherwise)

  - by mq.chen

  Hi, I guess this is probably a commonly asked and boring question but I'm really at a loss and I don't know what else to do. This might be a duplicate of other questions, but none of the solutions worked for me. I've Googled around and read just about anything I could find but I'm still puzzled as to why it doesn't work. The gist of my problem is that I have set-up Google Apps for a client of mine with the domain fintan.dk. Everthing works just excellent, except emails sent from *@fintan.dk (either with the Gmail web-interface or desktop client) to a non-Google Apps email gets a softfail (I have sent to my University email, an email hosted at MediaTemple and even Hotmail). The emails gets a pass when sent to a Google Apps or Gmail address though... (All emails from that domain are sent via email clients.) So this is what I have done so far: I've added the SPF record Google recommended (v=spf1 include:_spf.google.com ~all), waited several days hoping it would a DNS update delay problem. Now, three days later there is no change. I have verified the settings in the desktop clients several times. I have validated the records with validation tools like the SPF Query Tool, [email protected] and [email protected]. All of them validate and gives a pass, saying there shouldn't be a problem, but strangely there still is. So, I really don't know what else to do. Any help is very much appreciated. Thank you in advance!

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• Nginx save file to local disk

  - by Dean Chen

  My case is: In our China company, we have to access one web server in USA headquarter through Internet. But network is too slow, and we download many big image files. All our developers have to wait. So we want to setup a Nginx which acts as reverse proxy, its upstream is our USA web server. Question is can we make Nginx save the image files from USA web server into its local disk? I mean let Nginx act as one cache server.

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• Only allow the POST method for a specific file in a directory

  - by Dave Chen

  I have one file that should only be accessible via the POST method. /var/www/folder/index.php The document root is /var/www/ and index.php is nested inside a folder. My configurations are as follows: <Directory "/var/www/folder"> <Files "index.php"> order deny,allow Allow from all <LimitExcept POST> Deny from all </LimitExcept> </Files> </Directory> I visit my server at 127.0.0.1/folder but I can GET and POST the file just like normal. I've also tried reversing the order, order allow,deny, require, limitexcept and limit. How can I only allow POST requests to be processed by one file in a folder?

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• Can I disable the message line when launching ``screen -RR``

  - by Jimm Chen

  screen -RR is great. It does one of the two thing automatically: If there is any detached screen session, it picks up one can attach to it. If there is no detached screen session(no session yet, or all have been attach to other terminal), it creates a new screen session automatically. I use Windows server Remote Desktop a lot, screen -RR behaves almost the same when a client connects to a remote desktop server. It is natural and I like it. However, when screen -RR determines it should create a new session, it displays a message line at terminal bottom for 5 second. I'd like to suppress this message line because it brings us little benefit. In my opinion, a remote user can always easily distinguish whether he is connected to a resumed session(a piled-up display) or a newly created session(a clean display) from what he sees in the terminal window. So, is there a way to suppress the nag "New screen..." ? Just suppress that very one, not suppress message line globally. My env: opensuse 11.3, GNU screen 4.00.03 (FAU) 23-Oct-06

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• How do I know I'm running inside a linux "screen" or not?

  - by Jun Chen

  The "screen" refers to a program mentioned in How to reconnect to a disconnected ssh session . That is a good facility. But there is a question I'd really like to know. How do I know whether I'm running inside a "screen"? The difference is: If yes, I know I can safely close current terminal window, e.g., close a PuTTY window, without losing my shell(Bash etc) session. If no, I know I have to take care of any pending works before I close the terminal window. Better, I'd like this status to be displayed in PS1 prompt so that I can see it any time automatically.

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• Odd behavior in Django Form (readonly field/widget)

  - by jamida

  I'm having a problem with a test app I'm writing to verify some Django functionality. The test app is a small "grade book" application that is currently using Alex Gaynor's readonly field functionality http://lazypython.blogspot.com/2008/12/building-read-only-field-in-django.html There are 2 problems which may be related. First, when I flop the comment on these 2 lines below: # myform = GradeForm(data=request.POST, instance=mygrade) myform = GradeROForm(data=request.POST, instance=mygrade) it works like I expect, except of course that the student field is changeable. When the comments are the shown way, the "studentId" field is displayed as a number (not the name, problem 1) and when I hit submit I get an error saying that studentId needs to be a Student instance. I'm at a loss as to how to fix this. I'm not wedded to Alex Gaynor's code. ANY code will work. I'm relatively new to both Python and Django, so the hints I've seen on websites that say "making a read-only field is easy" are still beyond me. // models.py class Student(models.Model): name = models.CharField(max_length=50) parent = models.CharField(max_length=50) def __unicode__(self): return self.name class Grade(models.Model): studentId = models.ForeignKey(Student) finalGrade = models.CharField(max_length=3) # testbed.grades.readonly is alex gaynor's code from testbed.grades.readonly import ReadOnlyField class GradeROForm(ModelForm): studentId = ReadOnlyField() class Meta: model=Grade class GradeForm(ModelForm): class Meta: model=Grade // views.py def modifyGrade(request,student): student = Student.objects.get(name=student) mygrade = Grade.objects.get(studentId=student) if request.method == "POST": # myform = GradeForm(data=request.POST, instance=mygrade) myform = GradeROForm(data=request.POST, instance=mygrade) if myform.is_valid(): grade = myform.save() info = "successfully updated %s" % grade.studentId else: # myform=GradeForm(instance=mygrade) myform=GradeROForm(instance=mygrade) return render_to_response('grades/modifyGrade.html',locals()) // template <p>{{ info }}</p> <form method="POST" action=""> <table> {{ myform.as_table }} </table> <input type="submit" value="Submit"> </form> // Alex Gaynor's code from django import forms from django.utils.html import escape from django.utils.safestring import mark_safe from django.forms.util import flatatt class ReadOnlyWidget(forms.Widget): def render(self, name, value, attrs): final_attrs = self.build_attrs(attrs, name=name) if hasattr(self, 'initial'): value = self.initial return mark_safe("<span %s>%s</span>" % (flatatt(final_attrs), escape(value) or '')) def _has_changed(self, initial, data): return False class ReadOnlyField(forms.FileField): widget = ReadOnlyWidget def __init__(self, widget=None, label=None, initial=None, help_text=None): forms.Field.__init__(self, label=label, initial=initial, help_text=help_text, widget=widget) def clean(self, value, initial): self.widget.initial = initial return initial

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• Searches (and general querying) with HBase and/or Cassandra (best practices?)

  - by alexeypro

  I have User model object with quite few fields (properties, if you wish) in it. Say "firstname", "lastname", "city" and "year-of-birth". Each user also gets "unique id". I want to be able to search by them. How do I do that properly? How to do that at all? My understanding (will work for pretty much any key-value storage -- first goes key, then value) u:123456789 = serialized_json_object ("u" as a simple prefix for user's keys, 123456789 is "unique id"). Now, thinking that I want to be able to search by firstname and lastname, I can save in: f:Steve = u:384734807,u:2398248764,u:23276263 f:Alex = u:12324355,u:121324334 so key is "f" - which is prefix for firstnames, and "Steve" is actual firstname. For "u:Steve" we save as value all user id's who are "Steve's". That makes every search very-very easy. Querying by few fields (properties) -- say by firstname (i.e. "Steve") and lastname (i.e. "l:Anything") is still easy - first get list of user ids from "f:Steve", then list from "l:Anything", find crossing user ids, an here you go. Problems (and there are quite a few): Saving, updating, deleting user is a pain. It has to be atomic and consistent operation. Also, if we have size of value limited to some value - then we are in (potential) trouble. And really not of an answer here. Only zipping the list of user ids? Not too cool, though. What id we want to add new field to search by. Eventually. Say by "city". We certainly can do the same way "c:Los Angeles" = ..., "c:Chicago" = ..., but if we didn't foresee all those "search choices" from the very beginning, then we will have to be able to create some night job or something to go by all existing User records and update those "c:CITY" for them... Quite a big job! Problems with locking. User "u:123" updates his name "Alex", and user "u:456" updates his name "Alex". They both have to update "f:Alex" with their id's. That means either we get into overwriting problem, or one update will wait for another (and imaging if there are many of them?!). What's the best way of doing that? Keeping in mind that I want to search by many fields? P.S. Please, the question is about HBase/Cassandra/NoSQL/Key-Value storages. Please please - no advices to use MySQL and "read about" SELECTs; and worry about scaling problems "later". There is a reason why I asked MY question exactly the way I did. :-)

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• 3d implementation with Datacash

  - by Vijay Dabas

  Hi All/Alex, I am getting Based 64 not encoded for PaReq although I am actually encodin it. Please suggect some solution I know Alex asking same kind of question.

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• log4net dependency problem

  - by Alex DeLarge

  I have an issue with log4net which has been bugging me for a while and I've resolved to sort it. I have a class library which references log4net. If I reference this class library in another project I must then reference log4net in this project otherwise I get a build error Unknown build error, 'Cannot resolve dependency to assembly 'log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=1b44e1d426115821' because it has not been preloaded. When using the ReflectionOnly APIs, dependent assemblies must be pre-loaded or loaded on demand through the ReflectionOnlyAssemblyResolve event.' I'm aware that the error message is probably telling me the solution, unfortunately I don't speak gibberish... Cheers guys Alex..

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