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'Delete a Twitter entry' dissected

The following code was copied from my Twitter home page, it shows how to delete a twitter entry on the server.

raw HTML code with embedded JavaScript code.


<a href="/status/destroy/719423092" onclick="if (confirm('Sure you want to delete this update? There is NO undo!')) 
{var f = document.createElement('form'); f.style.display = 'none'; this.parentNode.appendChild(f); f.method = 
'POST'; f.action = this.href;var m = document.createElement('input'); m.setAttribute('type', 'hidden'); 
m.setAttribute('name', '_method'); m.setAttribute('value', 'delete'); f.appendChild(m);var s = 
document.createElement('input'); s.setAttribute('type', 'hidden'); s.setAttribute('name', 'authenticity_token'); 
s.setAttribute('value', 'd0057265c3784d2a6dc6cdb2c26083f638152151'); f.appendChild(s);f.submit(); };return false;" 
title="Delete this update?">

same code as above but with comments.

<a href="/status/destroy/719423092" onclick="

                     // if the user clicks the 'OK' button the confirm function will return true
if (confirm('Sure you want to delete this update? There is NO undo!')) { 

  // -- dhtml: creating html elements on-the-fly -------------------------------
  var f = document.createElement('form'); // create the dhtml 'form' (<form/>) element
  f.style.display = 'none';               // hide the form
  this.parentNode.appendChild(f);         // append the form element to the parent of the current node (<a/>)
  f.method = 'POST';                      // add the method to the form
  f.action = this.href;                   // add the action using the href of the current node (<a/>)
    
  var m = document.createElement('input');   // create the input (<input/>) 'element' 
  m.setAttribute('type', 'hidden');          // set the input type to 'hidden'
  m.setAttribute('name', '_method');         // set the input name to '_method'
  m.setAttribute('value', 'delete');         // set the input value to 'delete'
  f.appendChild(m);                          // append the input element to the form element
  
  var s = document.createElement('input');   // create another input element
  s.setAttribute('type', 'hidden');          // set the type to 'hidden'
  s.setAttribute('name', 'authenticity_token'); // set the name to 'authenticity_token'
  
                                     // set the input element's value using a unique id.
  s.setAttribute('value', 'd0057265c3784d2a6dc6cdb2c26083f638152151'); 
  
  f.appendChild(s);                  // apend the input element to the form element
  // -- end of dhtml: creating html elements on-the-fly -------------------------------
  
  f.submit(); // post the form data back to the server to delete the record, 
              // just as if the user had pressed the submit button.
};

  return false; // returning false cancels the default <a href="..."> request. 
                 // However if JavaScript had been disabled for some reason the 
                 // <a href="..."> would have acted normally, meaning the record 
                 // would have been deleted from following the URL request directly.
 "

Note: Twitter needs JavaScript for the web page to work properly, I've tried and it is not possible to delete a record without JavaScript. The authenticity_token has been altered by me to prevent any malicious activity on my Twitter account.

to javascript form input post dhtml delete twitter hidden by jrobertson on Feb 16, 2008

Empty a Directory with PHP

// ggarciaa at gmail dot com (04-July-2007 01:57)
// I needed to empty a directory, but keeping it
// so I slightly modified the contribution from
// stefano at takys dot it (28-Dec-2005 11:57)
// A short but powerfull recursive function
// that works also if the dirs contain hidden files
//
// $dir = the target directory
// $DeleteMe = if true delete also $dir, if false leave it alone
//
// SureRemoveDir('EmptyMe', false);
// SureRemoveDir('RemoveMe', true);

<?php
function SureRemoveDir($dir, $DeleteMe) {
    if(!$dh = @opendir($dir)) return;
    while (false !== ($obj = readdir($dh))) {
        if($obj=='.' || $obj=='..') continue;
        if (!@unlink($dir.'/'.$obj)) SureRemoveDir($dir.'/'.$obj, true);
    }

    closedir($dh);
    if ($DeleteMe){
        @rmdir($dir);
    }
}
?>

to php directory delete by demods on Jan 18, 2008

Mark directories to be deleted based on their date-stamp

This Ruby code selects file directories which are older than a certain date and outputs an XML file naming all the directories to be removed. It does this by reading a directory listing formatted within the XML file 'dir.xml', all directories are named by a date-stamp, which is used to determine if the directory should be removed.

This example is used to maintain the webcamera (named 'pear') which saves it's images to a date-stamped directory daily. Any directory which is older than 14 days will be marked for deletion.

  def directory_housekeeping()
    lifespan = 14
    format_mask = 'm_d_y'
    separator = format_mask.match(/[\_*\-]/).to_s
    
    earliest_date = Time.now + (60 * 60 * 24) * -lifespan
    cut_off_date = Date.new(y=earliest_date.year,m=earliest_date.month,d=earliest_date.day)
        
    a_format = Array.new
    a_format[0] = format_mask.match(/^[y,m,d]*/).to_s
    a_format[1] = format_mask.match(separator + '[y,m,d]*').to_s.gsub(separator,'')
    a_format[2] = format_mask.match('[y,m,d]$').to_s
    
    file = File.new('../housekeeping/webcam_pear/dir.xml')
    ddoc = REXML::Document.new(file)
    file.close
    
    file_delete = File.new('../housekeeping/webcam_pear/files2delete.xml', 'w')
    doc_delete = Document.new()
    doc_delete.add_element('files')
    
    ddoc.root.elements.each('file') do |file_node|
      sfile = file_node.text
      idate = Array.new
      idate[0] = sfile.match(/^\d*/).to_s.to_i
      idate[1] = sfile.match(/\_\d*/).to_s.gsub(separator,'').to_i
      idate[2] = sfile.match(/\_\d*\d$/).to_s.gsub(separator,'').to_i

      h = Hash.new
      0.upto(2) {|i| h[a_format[i]] = idate[i]}

      file_date = Date.new(y=h['y'], m=h['m'], d=h['d'])

      if file_date < cut_off_date
        o_file2delete = Element.new('file')
        o_file2delete.text = file_date.strftime(dformat)
        doc_delete.root.add_element o_file2delete
      end
    end
    file_delete.puts doc_delete
  end

file: dir.xml

<dir>
  <file>11_4_2007</file>
  <file>11_5_2007</file>
  <file>11_6_2007</file>
  <file>11_7_2007</file>
  <file>11_8_2007</file>
  <file>11_9_2007</file>
  <file>12_10_2007</file>
  <file>12_11_2007</file>
  <file>12_1_2007</file>
  <file>12_12_2007</file>
  <file>12_13_2007</file>
  <file>12_14_2007</file>
  <file>12_15_2007</file>
  <file>12_16_2007</file>
  <file>12_17_2007</file>
  <file>12_18_2007</file>
  <file>12_19_2007</file>
  <file>12_20_2007</file>
  <file>12_21_2007</file>
  <file>12_2_2007</file>
  <file>12_22_2007</file>
  <file>12_23_2007</file>
  <file>12_24_2007</file>
  <file>12_25_2007</file>
  <file>12_26_2007</file>
  <file>12_27_2007</file>
  <file>12_28_2007</file>
  <file>12_3_2007</file>
  <file>12_4_2007</file>
  <file>12_5_2007</file>
  <file>12_6_2007</file>
  <file>12_7_2007</file>
  <file>12_8_2007</file>
  <file>12_9_2007</file>
 </dir>

file: files2delete.xml

<files>
  <file>11_4_2007</file>
  <file>11_5_2007</file>
  <file>11_6_2007</file>
  <file>11_7_2007</file>
  <file>11_8_2007</file>
  <file>11_9_2007</file>
  <file>12_10_2007</file>
  <file>12_11_2007</file>
  <file>12_1_2007</file>
  <file>12_12_2007</file>
  <file>12_13_2007</file>
  <file>12_14_2007</file>
  <file>12_15_2007</file>
  <file>12_2_2007</file>
  <file>12_3_2007</file>
  <file>12_4_2007</file>
  <file>12_5_2007</file>
  <file>12_6_2007</file>
  <file>12_7_2007</file>
  <file>12_8_2007</file>
  <file>12_9_2007</file>
 </files>

to ruby date formatting xml directory validation file delete by jrobertson on Dec 30, 2007 2 Comments

Using Ruby to delete a file directory

In this example the file we want to delete is a non-empty directory called sample.

  require 'fileutils' 

  FileUtils.rm_r 'sample'

to ruby shell directory command delete by jrobertson on Dec 22, 2007

Hash#deep_delete


class Object
   def deep_clone
      Marshal.load(Marshal.dump(self))
   end
end


class Hash

   # From: http://www.sameshirteveryday.com/2007/09/23/ruby-get-full-history-all-parents-of-a-hash-node
   # Author: Alex Gorbatchev
   # for further recursive hash methods see: 
   # - http://snippets.dzone.com/posts/show/1908
   # - http://snippets.dzone.com/posts/show/4706
   
   def nested_key(desired_key, &block)

      return false unless Hash === self
      #return false unless self.is_a?(Hash)

      self.each_pair do |k,v|  
         if k == desired_key or v.nested_key(desired_key, &block)  
            yield(k,v)  
            return true  
         end  
      end  

      return false  
   end


   def deep_values(key)   # cf. http://snippets.dzone.com/posts/show/1908 

      hash = self.deep_clone
      ret = []

      begin

         ar = []
         result = hash.nested_key(key) { |k, v| ar << k }
         break unless result
         ar = ar.reverse

         hk = ""
         ar.size.times { |i| hk << "[ar[#{i}]]" }
         #str = "hash" << hk << " rescue nil"
         str = "hash" << hk 

         # get value for hash key hk
         ret << eval(str)

         # delete the hash key
         key_to_delete = [ar.pop]

         hk = ""
         ar.size.times { |i| hk << "[ar[#{i}]]" }
         str = "hash" << hk
         str = str << ".delete(key_to_delete.first)"
         eval(str)


      end while result

      hash.clear  # optional
      ret

   end


   def deep_delete(key)

      hash = self

      begin

         ar = []
         result = hash.nested_key(key) { |k, v| ar << k }
         break unless result
         ar = ar.reverse

         # delete the hash key
         key_to_delete = [ar.pop]

         hk = ""
         ar.size.times { |i| hk << "[ar[#{i}]]" }
         str = "hash" << hk
         str = str << ".delete(key_to_delete.first)"
         eval(str)

      end while result

   end

end



puts
hash = {  
  :level_1 => {  
    :level_2 => {  :search => 'test1',
      :level_3 => {  
        :search => 'test2', :level_4 => {:search => 'test3'}
      }  
    }  
  }  
}  


require 'pp'

p hash
puts

pp hash
puts

hash.nested_key(:search) { |k, v| puts "#{k}  ::  #{v.inspect}" }

# prints out...
# search  ::  "test1"
# level_2  ::  {:search=>"test1", :level_3=>{:search=>"test2", :level_4=>{:search=>"test3"}}}
# level_1  ::  {:level_2=>{:search=>"test1", :level_3=>{:search=>"test2", :level_4=>{:search=>"test3"}}}}

puts


puts "DEEP VALUES"
p hash.deep_values(:search)   #=> ["test1", "test2", "test3"]
puts

puts "DEEP VALUES DELETED"
hash.deep_delete(:search)
p hash   #=> {:level_1=>{:level_2=>{:level_3=>{:level_4=>{}}}}}
puts

puts "DEEP VALUES"
p hash.deep_values(:search)   #=> []

to ruby hash recursive delete deep by ntk on Nov 01, 2007

Deleting an xml node from a REXML::document

// Reads an XML file, then deletes the root element's 1st child element.

require 'rexml/document'
include REXML

file = File.new('journal250907.xml')
doc = Document.new(file)

puts doc

o_element = Element.new('abc')
o_element.text = "123"

o_node = doc.elements['journal/entry']

o_node.parent.delete(o_node)

to ruby rexml delete by jrobertson on Sep 26, 2007

DELETE - SQL

// description of your code here

DELETE ... 
    [ FROM ... ] 
    [ ... JOIN ... ] 
    [ WHERE ... ] 

// FULL Syntax follows:
DELETE [ FROM ] 
    {
       [ database. ] [ owner. ] table_name 
         [
           WITH (  INDEX ( Index_1,   [ index_2,  ...,  n ] ) 
                      | FASTFIRSTROW 
                      | HOLDLOCK 
                      | PAGLOCK 
                      | READCOMMITTED 
                      | REPEATABLEREAD 
                      | ROWLOCK 
                      | SERIALIZABLE 
                      | TABLOCK 
                      | TABLOCKX 
                      [   ...   n  |  ...,  n ] 
                     )
       ]
     |
       OPENQUERY( server, 'query' ) 
     |
       OPENROWSET( 'provider_name', 
                                 { 'datasource';'user_id';'password',  |  'provider_string', }
                                 { [ catalog. ] [ schema. ] object  |  'query' }
                               ) 
     |
       view_name 
    }

    [
      FROM 
      {
          derived_table 
            [ [ AS ] table_alias ]
            [ ( column_alias_1,   [ column_alias_2,   ...,  n ]  )  ]
        |
          CONTAINSTABLE ( table, column  |  *, 'search_conditions' ) 
            [ [ AS ] table_alias ]
        |
          FREETEXTTABLE ( table, column  |  *, 'free_text_string' ) 
            [ [ AS ] table_alias ]
        |
          table_name [ [ AS ] table_alias ]
            [
               WITH (  INDEX ( Index_1,   [ index_2,   ...,  n ]  ) 
                          | FASTFIRSTROW 
                          | HOLDLOCK 
                          | NOLOCK 
                          | PAGLOCK 
                          | READCOMMITTED 
                          | READPAST 
                          | READUNCOMMITTED 
                          | REPEATABLEREAD 
                          | ROWLOCK 
                          | SERIALIZABLE 
                          | TABLOCK 
                          | TABLOCKX 
                          | UPDLOCK 
                          [ ...   n  |  ...,  n ] 
                         )
            ]
        |
          view_name [ [ AS ] table_alias ]
      }





      [
          INNER JOIN  |  LEFT [ OUTER ] JOIN  |  RIGHT [ OUTER ] JOIN 
            {
               derived_table [ ON search_conditions ]
             |
               OPENQUERY( server, 'query' ) [ ON search_conditions ]
             |
               OPENROWSET
                               ( 'provider_name', 
                                 { 'datasource';'user_id';'password',  |  'provider_string', }
                                 { [ catalog. ] [ schema. ] object  |  'query' }
                               ) [ ON search_conditions ]
             | 
               table_name [ ON search_conditions ]
             | 
               view_name [ ON search_conditions ]
            }
            [   ...,  n ]
          |
          CROSS JOIN  |  FULL [ OUTER ] JOIN 
            {
               derived_table 
             | 
               OPENQUERY( server, 'query' ) 
             |
               OPENROWSET
                               ( 'provider_name', 
                                 { 'datasource';'user_id';'password',  |  'provider_string', }
                                 { [ catalog. ] [ schema. ] object  |  'query' }
                               ) 
             | 
               table_name 
             | 
               view_name 
            }
            [   ...,  n ]
       ]
   ] 

   [
      {
         WHERE search_conditions 
       |
         WHERE CURRENT OF [ GLOBAL ] cursor_name 
       |
         WHERE CURRENT OF cursor_variable_name 
      }
         [
           OPTION (  FAST number_rows 
                          | FORCE ORDER 
                          | HASH GROUP 
                          | ORDER GROUP 
                          | HASH JOIN 
                          | LOOP JOIN 
                          | MERGE JOIN 
                          | KEEP PLAN 
                          | MAXDOP 
                          | ROBUST PLAN 
                          | CONCAT UNION 
                          | HASH UNION 
                          | MERGE UNION 
                          [   ...,  n ]
                        )
         ]
   ]

//Full explanation follows:

KEYWORDS Keywords are denoted with upper case letters. Obey the spelling.

variables All user-supplied variables are denoted with lower case letters.

..., n Signifies that there can be more than one value in a comma delimited list. Note that the dots and n are not part of the code and must not appear in the SQL query.

... n Signifies that there can be more than one value in a blank space delimited list. Note that the dots and n are not part of the code and must not appear in the SQL query.

{ } Signifies that all, or some portion, of the code elements between the braces are required elements and must appear in the SQL query. Note that these braces are not part of the code and must not appear in the SQL query.

[ ] Signifies that the code elements between the square brackets can optionally appear in the SQL query, but are not required. Note that these brackets are not part of the code and must not appear in the SQL query.

| The or symbol signifies that you may use only one of the code elements or values from the possible choices. Note that the or symbol is not part of the code and must not appear in the SQL query.

to sql syntax delete join union SQL 2005 inner by dubby on Sep 06, 2007

SQL SERVER: Delete Duplicate Rows with Primary Id

Deletes duplicates (leaving one instance) where the table has a primary key. Good for tables with Id, DupColumn, DupColumn...

(This is MS-SQL specific)

DELETE
FROM 	TableName
WHERE 	Id NOT IN
	(SELECT 	MAX(Id)
        FROM   		TableName
        GROUP BY 	DuplicateColumName1, DuplicateColumName2)

to sql mssql delete duplicate SQL Server by cornerblue on Aug 31, 2007

Delete empty directories (UNIX)

// Shell command to delete empty directories. May have to run several times to get everything.

find . -type d -empty | xargs rmdir -

to unix shell directory command remove directories delete empty by jasonbentley on Nov 17, 2006 2 Comments

Confirm Delete with javascript

// confirm() returns true or false
// submit() is only called on true and submits the form

<h1>Howto Confirm Delete</h1>
<form action="delete.html" method="post">
<input type="button" onclick="if (confirm('sure?')) submit();" value="delete">
</form>

to html javascript delete confirm by ovhaag on Sep 16, 2006