DZone Snippets: delete code

'Delete a Twitter entry' dissected

jrobertson (James Robertson) — Sat, 16 Feb 2008 13:17:07 GMT

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.





title="Delete this update?">

same code as above but with comments.

 request. 

                 // However if JavaScript had been disabled for some reason the 

                 //  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.

Empty a Directory with PHP

demods () — Fri, 18 Jan 2008 13:58:47 GMT

// 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);



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);

    }

}

?>

Mark directories to be deleted based on their date-stamp

jrobertson (James Robertson) — Sun, 30 Dec 2007 17:33:47 GMT

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

file: files2delete.xml

Using Ruby to delete a file directory

jrobertson (James Robertson) — Sat, 22 Dec 2007 14:06:52 GMT

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



  require 'fileutils' 



  FileUtils.rm_r 'sample'

Hash#deep_delete

ntk () — Thu, 01 Nov 2007 15:42:50 GMT





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)   #=> []

Deleting an xml node from a REXML::document

jrobertson (James Robertson) — Wed, 26 Sep 2007 18:13:10 GMT

// 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)

DELETE - SQL

dubby (Dave) — Thu, 06 Sep 2007 10:30:33 GMT

// 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.

SQL SERVER: Delete Duplicate Rows with Primary Id

cornerblue (CornerBLUE, Inc.) — Fri, 31 Aug 2007 19:12:09 GMT

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)

Delete empty directories (UNIX)

jasonbentley (Jason Bentley) — Sat, 18 Nov 2006 03:21:34 GMT

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



find . -type d -empty | xargs rmdir -

Confirm Delete with javascript

ovhaag (Oliver Haag) — Sat, 16 Sep 2006 21:07:45 GMT

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



Howto Confirm Delete