TinyMce doesn't have support for maxlength, and putting maxlength in the textfield tag won't do anything either.
If you try to google for a solution, you might come across this site
Don't waste your time on it, because the solution is built with the old tinymce api, it wouldn't work. Instead, use the solution from this post.
J
Showing posts with label J. Show all posts
Showing posts with label J. Show all posts
Monday, September 29, 2008
RoR: attr_accessible with attachment_fu
If you try to use attr_accessible on any model with attachment_fu plugin,
you'll get an error.
This article explains why
J
you'll get an error.
This article explains why
J
Tuesday, September 23, 2008
Stack and Queue Implementation
Array in Ruby already has built in push and pop function you can use, but if you want to make it more strict and idiot proof, here's how you can implement it.
class Stack
def initialize
@stack = []
end
def push(x)
@stack.push(x)
end
def pop
@stack.pop unless is_empty?
end
def peek
@stack.last
end
def is_empty?
@stack.empty?
end
end
class Queue
def initialize
@queue = []
end
def enqueue(x)
@queue << x
end
def dequeue(x)
@queue.shift
end
def peek
@queue.first
end
def is_empty?
@queue.empty?
end
end
J
class Stack
def initialize
@stack = []
end
def push(x)
@stack.push(x)
end
def pop
@stack.pop unless is_empty?
end
def peek
@stack.last
end
def is_empty?
@stack.empty?
end
end
class Queue
def initialize
@queue = []
end
def enqueue(x)
@queue << x
end
def dequeue(x)
@queue.shift
end
def peek
@queue.first
end
def is_empty?
@queue.empty?
end
end
J
Fun with String
This is why Ruby is amazing :D
1. converting strings to numbers
"123".to_i => 123
Duh, everyone knows that
but how bout
"123stfu".to_i => 123
or
" 123stfu ".to_i => 123
you can even indicate the base of your conversion
"111".to_i(2) => 7 # treat it as a binary number
"111".to_i(8) => 73 # treat it as an octal
split a string and convert it to an interger
"123 456 789".split.map {|m| m.to_i} => [123, 456, 789]
2. Replacing text
we can implement the lame rot13 encryption scheme in one line :)
class String; def rot13; self.tr("A-Ma-mN-Zn-z", "N-Zn-zA-Ma-m");end;end
"Please hide this line".rot13 => "Cyrnfr uvqr guvf yvar"
3. Counting Characters
s1 = "abcabcabcde"
s1.count("c") => 3
s1.count("abc") => 9
s1.count(s1) => 11
count can handle negation
s1.count("^abc") => 2
s1.count("^a") => 8
and range of chars
s1.count("a-c") => 9
s1.count("^a-z") => 0
4. Reversing a String
Microsoft loves to ask interviewee to reverse the word order of a String during an interview, it takes around 15 - 20 lines to implement the function in Java or C++, but we can do it in one :)
phrase = "This is a joke"
phrase.split.reverse.join(" ") => "joke a is This"
so next time you goto an interview, asks if they'll let you do it in Ruby ;)
5. Removing Duplicate Characters
string = "aaaaaaaaaaaaaaaaaaa".squeeze => "a"
string = "aaaaaaaaaaaaaaaaaaB".squeeze => "aB"
string = "hehe....".squeeze(".") => "hehe."
J
1. converting strings to numbers
"123".to_i => 123
Duh, everyone knows that
but how bout
"123stfu".to_i => 123
or
" 123stfu ".to_i => 123
you can even indicate the base of your conversion
"111".to_i(2) => 7 # treat it as a binary number
"111".to_i(8) => 73 # treat it as an octal
split a string and convert it to an interger
"123 456 789".split.map {|m| m.to_i} => [123, 456, 789]
2. Replacing text
we can implement the lame rot13 encryption scheme in one line :)
class String; def rot13; self.tr("A-Ma-mN-Zn-z", "N-Zn-zA-Ma-m");end;end
"Please hide this line".rot13 => "Cyrnfr uvqr guvf yvar"
3. Counting Characters
s1 = "abcabcabcde"
s1.count("c") => 3
s1.count("abc") => 9
s1.count(s1) => 11
count can handle negation
s1.count("^abc") => 2
s1.count("^a") => 8
and range of chars
s1.count("a-c") => 9
s1.count("^a-z") => 0
4. Reversing a String
Microsoft loves to ask interviewee to reverse the word order of a String during an interview, it takes around 15 - 20 lines to implement the function in Java or C++, but we can do it in one :)
phrase = "This is a joke"
phrase.split.reverse.join(" ") => "joke a is This"
so next time you goto an interview, asks if they'll let you do it in Ruby ;)
5. Removing Duplicate Characters
string = "aaaaaaaaaaaaaaaaaaa".squeeze => "a"
string = "aaaaaaaaaaaaaaaaaaB".squeeze => "aB"
string = "hehe....".squeeze(".") => "hehe."
J
List of reflective methods
I find the following commands very useful from time to time, but I kept forgetting their names. So I'm creating this post to help remind myself.
a.class
# returns the class of an object a
a.superclass
# returns the superclass of an object a
a.instance_of? A
# determines if a.class == A
a.is_a? A
#determines whether a is an instance of c, or of any of its subclass, or of any modules.
a.respond_to? :something
#determines if a has a public or protected method with the specified name.
J
a.class
# returns the class of an object a
a.superclass
# returns the superclass of an object a
a.instance_of? A
# determines if a.class == A
a.is_a? A
#determines whether a is an instance of c, or of any of its subclass, or of any modules.
a.respond_to? :something
#determines if a has a public or protected method with the specified name.
J
Monday, September 22, 2008
Duck Typing and Type Checking
Consider the following example:
class A
attr_accessor :x
def initialize
@x = 0
end
def +(other)
a = A.new
a.x = @x + other.x
return a
end
end
class B
attr_accessor :x
def initialize
@x = 0
end
end
a = A.new
a.x = 10
b = B.new
b.x = 5
puts (a+b).x # this will return 15
Ruby is a very dynamic language, the addition function doesn't care if the argument passed in is of type A, as long as it looks and behaves like A. This is called duck typing, name after the phase "if it walks like a duck and quacks like a duck, it must be a duck!"
if you want to ensure the object passed into the + function has to have an x accessor, you can add this to def +(other)
raise "error" unless other.respond_to? :x
or if you want to ensure object passed into the + function has to be of class A, you can add this instead:
raise "error" unless other.is_a? A
J
class A
attr_accessor :x
def initialize
@x = 0
end
def +(other)
a = A.new
a.x = @x + other.x
return a
end
end
class B
attr_accessor :x
def initialize
@x = 0
end
end
a = A.new
a.x = 10
b = B.new
b.x = 5
puts (a+b).x # this will return 15
Ruby is a very dynamic language, the addition function doesn't care if the argument passed in is of type A, as long as it looks and behaves like A. This is called duck typing, name after the phase "if it walks like a duck and quacks like a duck, it must be a duck!"
if you want to ensure the object passed into the + function has to have an x accessor, you can add this to def +(other)
raise "error" unless other.respond_to? :x
or if you want to ensure object passed into the + function has to be of class A, you can add this instead:
raise "error" unless other.is_a? A
J
Instance Variable
Java and C++ programmers are used to declaring their variables in a class, and they think they should do the same in Ruby. WRONG!
For example:
class Animal
@age = 0
@name = ""
def initialize(age, name)
@age = age
@name = name
end
end
In this example, two sets of @age, @name are created. When the initialize method is called, self holds an instance of the Animal class. But the code outside of that function are executed as part of the definition of the Animal class. When @age and @name are executed, it refers to the Animal class, not the object instance. Hence @age, @name inside the initialize function are different from the @age, @name on the outside.
J
For example:
class Animal
@age = 0
@name = ""
def initialize(age, name)
@age = age
@name = name
end
end
In this example, two sets of @age, @name are created. When the initialize method is called, self holds an instance of the Animal class. But the code outside of that function are executed as part of the definition of the Animal class. When @age and @name are executed, it refers to the Animal class, not the object instance. Hence @age, @name inside the initialize function are different from the @age, @name on the outside.
J
Sunday, September 21, 2008
Variable Parameters
Sometimes we want a method that can take any number of parameters.
One way to do it is to pass in a hash, but this can be annoying. Another method is to put an * before the method's parameter. Within the body of the method, list will be treated as an array with 0 or more elements.
For example:
def average(*list)
x = 0
list.each {|l| x+= l}
l/list.size
end
irb>average 1,2,3,4,5,6,7,8,9
=> 5
J
One way to do it is to pass in a hash, but this can be annoying. Another method is to put an * before the method's parameter. Within the body of the method, list will be treated as an array with 0 or more elements.
For example:
def average(*list)
x = 0
list.each {|l| x+= l}
l/list.size
end
irb>average 1,2,3,4,5,6,7,8,9
=> 5
J
Copying Objects
When you use =, clone, or dup to copy an object, only the object reference is copied,
not the referenced object itself (Shallow Copy).
In order to do a deep object copy, we can use the marshaling trick by dumping and
loading the object.
For example:
def deepcopy(something)
Marshal.load(Marshal.dump(something))
end
irb>b = "abcd"
=> "abcd"
irb>a = b
=> "abcd"
irb>a.upcase!
=>"ABCD"
irb>b
=>"ABCD" # see how b changes too
irb>b = deepcopy(a)
=>"ABCD"
irb>b.downcase!
=>"abcd"
irb>a
=>"ABCD" # a stayed the same this time
J
not the referenced object itself (Shallow Copy).
In order to do a deep object copy, we can use the marshaling trick by dumping and
loading the object.
For example:
def deepcopy(something)
Marshal.load(Marshal.dump(something))
end
irb>b = "abcd"
=> "abcd"
irb>a = b
=> "abcd"
irb>a.upcase!
=>"ABCD"
irb>b
=>"ABCD" # see how b changes too
irb>b = deepcopy(a)
=>"ABCD"
irb>b.downcase!
=>"abcd"
irb>a
=>"ABCD" # a stayed the same this time
J
Saturday, September 20, 2008
More on enumerable
In ruby, I use .each alot to visit every elements in the array.
Did you know there's a .step(x) function that allows you to visit
every x th element in the array?
For example:
r = 0..3
r.each {|l| prints l.to_s + ' ' } # Prints 0 1 2 3
r.step(2) {|l| prints l.to_s + ' '} # Prints 0 2
J
Did you know there's a .step(x) function that allows you to visit
every x th element in the array?
For example:
r = 0..3
r.each {|l| prints l.to_s + ' ' } # Prints 0 1 2 3
r.step(2) {|l| prints l.to_s + ' '} # Prints 0 2
J
Thousands Seperator
In ruby, underscore can be inserted into integer literals as thousands separator.
For example:
1_000 will be interpreted as 1000
1_000 + 1_000 will equal 2000
1_000_000_000 will be interpreted as 1 billion
the same technique works for float number as well
For example:
1_000.1 will be interpreted as 1000.1
J
For example:
1_000 will be interpreted as 1000
1_000 + 1_000 will equal 2000
1_000_000_000 will be interpreted as 1 billion
the same technique works for float number as well
For example:
1_000.1 will be interpreted as 1000.1
J
Saturday, July 12, 2008
Uploading large file to nginx server
If you upload a file over 1M in size to a nginx server, you might get a "Request Entity Too Large" (413) error.
We can overcome this problem by specifying the client_max_body_size in nginx.conf
nano /etc/nginx/nginx.conf
under "server {"
add the following line
client_max_body_size 5M
this will change the max file size to 5M, you can change that number to whatever you like.
J
We can overcome this problem by specifying the client_max_body_size in nginx.conf
nano /etc/nginx/nginx.conf
under "server {"
add the following line
client_max_body_size 5M
this will change the max file size to 5M, you can change that number to whatever you like.
J
Thursday, May 22, 2008
Remote Host Identification has Changed
I just reinstalled our main server. When I try to ssh into it I got an error:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that the RSA host key has just been changed.
Please contact your system administrator.
Add correct host key in /home/user/.ssh/known_hosts to get rid of this message.
Offending key in /home/user/.ssh/known_hosts:1
RSA host key for ras.mydomain.com has changed and you have requested strict checking.
Host key verification failed.
-----------------------------------------------------------
The reason behind this is because your local computer still has the old RSA host key stored in /home/your_account/.ssh/known_hosts.
The easiest way to solve this problem is simply delete that file or you can delete the host entry in the file.
Joseph
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that the RSA host key has just been changed.
Please contact your system administrator.
Add correct host key in /home/user/.ssh/known_hosts to get rid of this message.
Offending key in /home/user/.ssh/known_hosts:1
RSA host key for ras.mydomain.com has changed and you have requested strict checking.
Host key verification failed.
-----------------------------------------------------------
The reason behind this is because your local computer still has the old RSA host key stored in /home/your_account/.ssh/known_hosts.
The easiest way to solve this problem is simply delete that file or you can delete the host entry in the file.
Joseph
Friday, May 2, 2008
VMware on Hardy
There is currently no vmware package for hardy (DAMNIT!!). So we gotta do it the hard way.
1. apt-get the following
sudo apt-get install build-essential linux-headers-`uname -r`
sudo apt-get install xinetd
2. download the vmware tarball
just goto the website, it's constantly changing so I wouldn't bother posting it.
3. Get your FREE registration number (this used to cost a fortune, lucky us)
http://register.vmware.com/content/registration.html
4. Extract the tarball somewhere and run it by doing
tar -zxvf xxx.tar.gz
go into the directory
sudo ./vmware-install.pl
5. Now it'll ask you bunch of questions, just keep pressing enter. After awhile, it'll start compiling and fail :)
6. This has something to do with hardy's kernel, but don't worry, there's a patch for it.
wget http://uruz.org/files/vmware-any-any-update-116.tgz
tar -xvzf vmware-any-any-update116.tgz
cd vmware-any-any-update116
sudo ./runme.pl
7. VMware should start compiling and asks you more questions after (just keep pressing enter)
8. Once you've configured your vmware server, you need to link up some libraries
sudo ln -sf /lib/libgcc_s.so.1 /usr/lib/vmware/lib/libgcc_s.so.1/libgcc_s.so.1
sudo ln -sf /usr/lib/libpng12.so.0 /usr/lib/vmware/lib/libpng12.so.0/libpng12.so.0
9. And that's it, you can launch it by typing vmware on your console
J
1. apt-get the following
sudo apt-get install build-essential linux-headers-`uname -r`
sudo apt-get install xinetd
2. download the vmware tarball
just goto the website, it's constantly changing so I wouldn't bother posting it.
3. Get your FREE registration number (this used to cost a fortune, lucky us)
http://register.vmware.com/content/registration.html
4. Extract the tarball somewhere and run it by doing
tar -zxvf xxx.tar.gz
go into the directory
sudo ./vmware-install.pl
5. Now it'll ask you bunch of questions, just keep pressing enter. After awhile, it'll start compiling and fail :)
6. This has something to do with hardy's kernel, but don't worry, there's a patch for it.
wget http://uruz.org/files/vmware-any-any-update-116.tgz
tar -xvzf vmware-any-any-update116.tgz
cd vmware-any-any-update116
sudo ./runme.pl
7. VMware should start compiling and asks you more questions after (just keep pressing enter)
8. Once you've configured your vmware server, you need to link up some libraries
sudo ln -sf /lib/libgcc_s.so.1 /usr/lib/vmware/lib/libgcc_s.so.1/libgcc_s.so.1
sudo ln -sf /usr/lib/libpng12.so.0 /usr/lib/vmware/lib/libpng12.so.0/libpng12.so.0
9. And that's it, you can launch it by typing vmware on your console
J
Monday, April 28, 2008
Hardy Heron Connection Problem
Just upgraded to Hardy two days ago. Is it nice? Yes. Is there any problems with it? Yes.
Installation was fast as usual, took around 20 mins. Video settings, sound card, network card ... are all setup and ready to go after the system rebooted itself. Firefox 3 looks better than ever, however, I can't seem to get a connection?!?
What's more weird is that I can actually goto google.com, but everything else will time out on me!
After hours of searching, some dude suggested that I should decrease the MTU (maximum transmission unit) from 1500 (standard for ethernet) to 1492 by typing the following command
sudo ifconfig eth0 mtu 1492
amazingly, my connection is back to normal! (if anyone know why that is, can you please educate me on this issue? I really like to know the reason behind this!)
J
Installation was fast as usual, took around 20 mins. Video settings, sound card, network card ... are all setup and ready to go after the system rebooted itself. Firefox 3 looks better than ever, however, I can't seem to get a connection?!?
What's more weird is that I can actually goto google.com, but everything else will time out on me!
After hours of searching, some dude suggested that I should decrease the MTU (maximum transmission unit) from 1500 (standard for ethernet) to 1492 by typing the following command
sudo ifconfig eth0 mtu 1492
amazingly, my connection is back to normal! (if anyone know why that is, can you please educate me on this issue? I really like to know the reason behind this!)
J
Thursday, April 17, 2008
Responds_to_parent loc error
If the rjs inside your responds_to_parent block ended up removing the iframe from your html page, the loc variable will no longer be defined.
Besides having an ugly error message on your firebug console, it can actually cause problems for the javascripts on that page as well.
In order the get around this problem, you'll need to do the following patches:
in parent_selector_assertion.rb and responds_to_parent.rb
replace all occurrence of
(3 in parent_selector_assertion, 1 in responds_to_parent) and that's it!
J
Besides having an ugly error message on your firebug console, it can actually cause problems for the javascripts on that page as well.
In order the get around this problem, you'll need to do the following patches:
in parent_selector_assertion.rb and responds_to_parent.rb
replace all occurrence of
(3 in parent_selector_assertion, 1 in responds_to_parent) and that's it!
J
Monday, March 31, 2008
Ruby Exception Hiearchy
For those who wants a better understand of the exception hiearchy, here it is!
Exception
Errno
NoMemoryError
ScriptError
LoadError
NotImplementedError
SyntaxError
SignalException
Interrupt
StandardError
ArgumentError
IOError
EOFError
IndexError
LocalJumpError
NameError
NoMethodError
RangeError
FloatDomainError
RegexpError
RuntimeError
SecurityError
SystemCallError
SystemStackError
ThreadError
TypeError
ZeroDivisionError
SystemExit
SystemStackError
Cheers,
Joseph
Exception
Errno
NoMemoryError
ScriptError
LoadError
NotImplementedError
SyntaxError
SignalException
Interrupt
StandardError
ArgumentError
IOError
EOFError
IndexError
LocalJumpError
NameError
NoMethodError
RangeError
FloatDomainError
RegexpError
RuntimeError
SecurityError
SystemCallError
SystemStackError
ThreadError
TypeError
ZeroDivisionError
SystemExit
SystemStackError
Cheers,
Joseph
Monday, March 17, 2008
Bugzilla Installation on Ubuntu
the installation guide on bugzilla's website scares me, you can easily spend over a day in order to get it up and running. Fortunately, that's not the case for ubuntu.
with the help of apt-get, we can easily cut it down to 15 mins
1. apt-get install mysql-server (if it's not already there)
2. then follow on screen instructions
3. mysql -u - root -p (we need to create a new user called bugzilla)
4. GRANT ALL PRIVILEGES ON *.* TO 'bugzilla'@'localhost' IDENTIFIED BY 'password';
5. \q
6. apt-get install bugzilla (we are half way done already lol)
7. follow on screen instructions
and you are done! goto http://yourserver/bugzilla and start using it.
the package we just installed is version 2.2, for those who want the latest and greatest, please keep reading, I need another 15 minutes of your time.
1. goto /var/www/ and wget the latest tarball from bugzilla
2. tar -zxvf the_file_you_just_downloaded.tar.gz
3. log back into mysql and create a 'bugs' account (step 3 and 4 from previous section)
4. cd into the newly extracted bugzilla folder
5. cp -pr ../bugzilla/data .
6. sudo ./checksetup.pl
7. sudo chmod -R 755 .
8. sudo chomd -R 755 /var/lib/bugzilla/data
9. open /etc/apache2/httpd.conf
add the following line to the bottom (if it's not there)
with the help of apt-get, we can easily cut it down to 15 mins
1. apt-get install mysql-server (if it's not already there)
2. then follow on screen instructions
3. mysql -u - root -p (we need to create a new user called bugzilla)
4. GRANT ALL PRIVILEGES ON *.* TO 'bugzilla'@'localhost' IDENTIFIED BY 'password';
5. \q
6. apt-get install bugzilla (we are half way done already lol)
7. follow on screen instructions
and you are done! goto http://yourserver/bugzilla and start using it.
the package we just installed is version 2.2, for those who want the latest and greatest, please keep reading, I need another 15 minutes of your time.
1. goto /var/www/ and wget the latest tarball from bugzilla
2. tar -zxvf the_file_you_just_downloaded.tar.gz
3. log back into mysql and create a 'bugs' account (step 3 and 4 from previous section)
4. cd into the newly extracted bugzilla folder
5. cp -pr ../bugzilla/data .
6. sudo ./checksetup.pl
7. sudo chmod -R 755 .
8. sudo chomd -R 755 /var/lib/bugzilla/data
9. open /etc/apache2/httpd.conf
add the following line to the bottom (if it's not there)
J10. restart the server : sudo /etc/init.d/apache2 restart<Directory /var/www/bugzilla>
AddHandler cgi-script .cgi
Options +Indexes +ExecCGI
DirectoryIndex index.cgi
AllowOverride Limit
</Directory>
11. rename the newly extracted folder to bugzilla
12. enjoy
Saturday, March 15, 2008
Postgres + Rails + Ubuntu Troubleshooting
Problem 1 - forgotten password for postgres
Solution - TOUGH! you gotta re-install, that's what happened to me
Problem 2 - sudo apt-get remove postgresql did not remove any of the configuration files
Solution - use apt-get purge postgresql instead, this applies to all other packages
Problem 3 - sudo apt-get purge postgresql did not remove all the associated files
Solution - use sudo apt-get purge postgresql* instead or you can run apt-get autoclean after
Problem 4 - postgres refuses connection, but I swear I entered the password correctly!!!
Solution - postgres is very protective, the account you are logging in must match your current linux account .
Problem 5 - But what if I want postgres to manage its own account?
Solution - edit /etc/postgresql/8.1/main/pg_hba.conf, look near the bottom of the file, modify "Unix domain Socket" to local all all md5, "IPv4 local connections" to host all all 127.0.0.1/32 md5
and don't forget to restart the server by doing /etc/init.d/postgres-8.2 restart
Problem 6 - I installed postgres-pr but rails can't connect to postgres and I tried installing the
regular postgres gem but it failed!
Solution - in order to install the postgres gem, make sure you have the libpq-dev gem installed first. (gem install libpq-dev). Try installing the postgres gem again, it should work!
Problem 7 - I want postgres to run on some other port, what can I do?
Solution - first edit the /etc/postgresql/8.2/main/postgresql.conf, change the port number there first (don't forget to restart the server) then you have to goto your rails directly and edit config/database.yml, add ":port [portnumber]" to all your environments.
J
Solution - TOUGH! you gotta re-install, that's what happened to me
Problem 2 - sudo apt-get remove postgresql did not remove any of the configuration files
Solution - use apt-get purge postgresql instead, this applies to all other packages
Problem 3 - sudo apt-get purge postgresql did not remove all the associated files
Solution - use sudo apt-get purge postgresql* instead or you can run apt-get autoclean after
Problem 4 - postgres refuses connection, but I swear I entered the password correctly!!!
Solution - postgres is very protective, the account you are logging in must match your current linux account .
Problem 5 - But what if I want postgres to manage its own account?
Solution - edit /etc/postgresql/8.1/main/pg_hba.conf, look near the bottom of the file, modify "Unix domain Socket" to local all all md5, "IPv4 local connections" to host all all 127.0.0.1/32 md5
and don't forget to restart the server by doing /etc/init.d/postgres-8.2 restart
Problem 6 - I installed postgres-pr but rails can't connect to postgres and I tried installing the
regular postgres gem but it failed!
Solution - in order to install the postgres gem, make sure you have the libpq-dev gem installed first. (gem install libpq-dev). Try installing the postgres gem again, it should work!
Problem 7 - I want postgres to run on some other port, what can I do?
Solution - first edit the /etc/postgresql/8.2/main/postgresql.conf, change the port number there first (don't forget to restart the server) then you have to goto your rails directly and edit config/database.yml, add ":port [portnumber]" to all your environments.
J
Sunday, March 2, 2008
Mcolumn reference "id" is ambiguous
Today I tried to improve the performance of my action by doing just one db call through eager loading. For those who have no idea what it is, please read our previous post
http://twoblinddevs.blogspot.com/search?q=eager+loading
This is what I wanted to do
Person.find(:first, :include=>[ :person_info, :messages], :conditions=>["id = :user_id", { :user_id => session[:id]}] )
when I refreshed the browser, it shows me this error message - Mcolumn reference "id" is ambiguous.
The reason rails complain is because all three tables have an id column. In order to work around this problem, you simply have to change id = :user_id to people.id = :user_id
J
http://twoblinddevs.blogspot.com/search?q=eager+loading
This is what I wanted to do
Person.find(:first, :include=>[ :person_info, :messages], :conditions=>["id = :user_id", { :user_id => session[:id]}] )
when I refreshed the browser, it shows me this error message - Mcolumn reference "id" is ambiguous.
The reason rails complain is because all three tables have an id column. In order to work around this problem, you simply have to change id = :user_id to people.id = :user_id
J
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