1: # The LearningOnline Network with CAPA
2: # MySQL utility functions
3: #
4: # $Id: lonmysql.pm,v 1.5 2002/08/09 17:08:19 matthew Exp $
5: #
6: # Copyright Michigan State University Board of Trustees
7: #
8: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
9: #
10: # LON-CAPA is free software; you can redistribute it and/or modify
11: # it under the terms of the GNU General Public License as published by
12: # the Free Software Foundation; either version 2 of the License, or
13: # (at your option) any later version.
14: #
15: # LON-CAPA is distributed in the hope that it will be useful,
16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18: # GNU General Public License for more details.
19: #
20: # You should have received a copy of the GNU General Public License
21: # along with LON-CAPA; if not, write to the Free Software
22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23: #
24: # /home/httpd/html/adm/gpl.txt
25: #
26: # http://www.lon-capa.org/
27: #
28: ######################################################################
29:
30: package Apache::lonmysql;
31:
32: use strict;
33: use DBI;
34: use Apache::lonnet();
35:
36: ######################################################################
37: ######################################################################
38:
39: =pod
40:
41: =head1 Name
42:
43: lonmysql - LONCAPA MySQL utility functions
44:
45: =head1 Synopsis
46:
47: lonmysql contains utility functions to make accessing the mysql loncapa
48: database easier.
49:
50: =head1 Description
51:
52: lonmysql does its best to encapsulate all the database/table functions
53: and provide a common interface. The goal, however, is not to provide
54: a complete reimplementation of the DBI interface. Instead we try to
55: make using mysql as painless as possible.
56:
57: Each table has a numeric ID that is a parameter to most lonmysql functions.
58: The table id is returned by &create_table.
59: If you lose the table id, it is lost forever.
60: The table names in MySQL correspond to
61: $ENV{'user.name'}.'_'.$ENV{'user.domain'}.'_'.$table_id. If the table id
62: is non-numeric, it is assumed to be the full name of a table. If you pass
63: the table id in a form, you MUST ensure that what you send to lonmysql is
64: numeric, otherwise you are opening up all the tables in the MySQL database.
65:
66: =over 4
67:
68: =item Creating a table
69:
70: To create a table, you need a description of its structure. See the entry
71: for &create_table for a description of what is needed.
72:
73: $table_id = &create_table({
74: columns => {
75: id => {
76: type => 'INT',
77: restrictions => 'NOT NULL',
78: primary_key => 'yes',
79: auto_inc => 'yes'
80: }
81: verbage => { type => 'TEXT' },
82: },
83: column_order => [qw/id verbage idx_verbage/],
84: fulltext => [qw/verbage/],
85: });
86:
87: The above command will create a table with two columns, 'id' and 'verbage'.
88:
89: 'id' will be an integer which is autoincremented and non-null.
90:
91: 'verbage' will be of type 'TEXT', which (conceivably) allows any length
92: text string to be stored. Depending on your intentions for this database,
93: setting restrictions => 'NOT NULL' may help you avoid storing empty data.
94:
95: the fulltext element sets up the 'verbage' column for 'FULLTEXT' searching.
96:
97:
98:
99: =item Storing rows
100:
101: Storing a row in a table requires calling &store_row($table_id,$data)
102:
103: $data is either a hash reference or an array reference. If it is an array
104: reference, the data is passed as is (after being escaped) to the
105: "INSERT INTO <table> VALUES( ... )" SQL command. If $data is a hash reference,
106: the data will be placed into an array in the proper column order for the table
107: and then passed to the database.
108:
109: An example of inserting into the table created above is:
110:
111: &store_row($table_id,[undef,'I am not a crackpot!']);
112:
113: or equivalently,
114:
115: &store_row($table_id,{ verbage => 'I am not a crackpot!'});
116:
117: Since the above table was created with the first column ('id') as
118: autoincrement, providing a value is unnecessary even though the column was
119: marked as 'NOT NULL'.
120:
121:
122:
123: =item Retrieving rows
124:
125: Retrieving rows requires calling get_rows:
126:
127: @row = &Apache::lonmysql::get_rows($table_id,$condition)
128:
129: This results in the query "SELECT * FROM <table> HAVING $condition".
130:
131: @row = &Apache::lonmysql::get_rows($table_id,'id>20');
132:
133: returns all rows with column 'id' greater than 20.
134:
135: =back
136:
137: =cut
138:
139: ######################################################################
140: ######################################################################
141: =pod
142:
143: =head1 Package Variables
144:
145: =over 4
146:
147: =cut
148:
149: ##################################################
150: ##################################################
151:
152: =pod
153:
154: =item %Tables
155:
156: Holds information regarding the currently open connections. Each key
157: in the %Tables hash will be a unique table key. The value associated
158: with a key is a hash reference. Most values are initialized when the
159: table is created.
160:
161: The following entries are allowed in the hash reference:
162:
163: =over 4
164:
165: =item Name
166:
167: Table name.
168:
169: =item Type
170:
171: The type of table, typically MyISAM.
172:
173: =item Row_format
174:
175: Describes how rows should be stored in the table. DYNAMIC or STATIC.
176:
177: =item Create_time
178:
179: The date of the tables creation.
180:
181: =item Update_time
182:
183: The date of the last modification of the table.
184:
185: =item Check_time
186:
187: Usually NULL.
188:
189: =item Avg_row_length
190:
191: The average length of the rows.
192:
193: =item Data_length
194:
195: The length of the data stored in the table (bytes)
196:
197: =item Max_data_length
198:
199: The maximum possible size of the table (bytes).
200:
201: =item Index_length
202:
203: The length of the index for the table (bytes)
204:
205: =item Data_free
206:
207: I have no idea what this is.
208:
209: =item Comment
210:
211: The comment associated with the table.
212:
213: =item Rows
214:
215: The number of rows in the table.
216:
217: =item Auto_increment
218:
219: The value of the next auto_increment field.
220:
221: =item Create_options
222:
223: I have no idea.
224:
225: =item Col_order
226:
227: an array reference which holds the order of columns in the table.
228:
229: =item row_insert_sth
230:
231: The statement handler for row inserts.
232:
233: =back
234:
235: Col_order and row_insert_sth are kept internally by lonmysql and are not
236: part of the usual MySQL table information.
237:
238: =cut
239:
240: ##################################################
241: ##################################################
242: my %Tables;
243:
244: ##################################################
245: ##################################################
246: =pod
247:
248: =item $errorstring
249:
250: Holds the last error.
251:
252: =cut
253: ##################################################
254: ##################################################
255: my $errorstring;
256:
257: ##################################################
258: ##################################################
259: =pod
260:
261: =item $debugstring
262:
263: Describes current events within the package.
264:
265: =cut
266: ##################################################
267: ##################################################
268: my $debugstring;
269:
270: ##################################################
271: ##################################################
272:
273: =pod
274:
275: =item $dbh
276:
277: The database handler; The actual connection to MySQL via the perl DBI.
278:
279: =cut
280:
281: ##################################################
282: ##################################################
283: my $dbh;
284:
285: ##################################################
286: ##################################################
287:
288: # End of global variable declarations
289:
290: =pod
291:
292: =back
293:
294: =cut
295:
296: ######################################################################
297: ######################################################################
298:
299: =pod
300:
301: =head1 Internals
302:
303: =over 4
304:
305: =cut
306:
307: ######################################################################
308: ######################################################################
309:
310: =pod
311:
312: =item &connect_to_db()
313:
314: Inputs: none.
315:
316: Returns: undef on error, 1 on success.
317:
318: Checks to make sure the database has been connected to. If not, the
319: connection is established.
320:
321: =cut
322:
323: ###############################
324: sub connect_to_db {
325: return 1 if ($dbh);
326: if (! ($dbh = DBI->connect("DBI:mysql:loncapa","www",
327: $Apache::lonnet::perlvar{'lonSqlAccess'},
328: { RaiseError=>0,PrintError=>0}))) {
329: $debugstring = "Unable to connect to loncapa database.";
330: if ($dbh->err) {
331: $errorstring = "Connection error: ".$dbh->errstr;
332: }
333: return undef;
334: }
335: $debugstring = "Successfully connected to loncapa database.";
336: return 1;
337: }
338:
339: ###############################
340:
341: =pod
342:
343: =item &disconnect_from_db()
344:
345: Inputs: none.
346:
347: Returns: Always returns 1.
348:
349: Severs the connection to the mysql database.
350:
351: =cut
352:
353: ###############################
354: sub disconnect_from_db {
355: foreach (keys(%Tables)) {
356: # Supposedly, having statement handlers running around after the
357: # database connection has been lost will cause trouble. So we
358: # kill them off just to be sure.
359: if (exists($Tables{$_}->{'row_insert_sth'})) {
360: delete($Tables{$_}->{'row_insert_sth'});
361: }
362: }
363: $dbh->disconnect if ($dbh);
364: $debugstring = "Disconnected from database.";
365: $dbh = undef;
366: return 1;
367: }
368:
369: ###############################
370:
371: =pod
372:
373: =item &number_of_rows()
374:
375: Input: table identifier
376:
377: Returns: the number of rows in the given table, undef on error.
378:
379: =cut
380:
381: ###############################
382: sub number_of_rows {
383: my ($table_id) = @_;
384: return undef if (! defined(&connect_to_db()));
385: return undef if (! defined(&update_table_info($table_id)));
386: return $Tables{&translate_id($table_id)}->{'Rows'};
387: }
388:
389: ###############################
390:
391: =pod
392:
393: =item &get_error()
394:
395: Inputs: none.
396:
397: Returns: The last error reported.
398:
399: =cut
400:
401: ###############################
402: sub get_error {
403: return $errorstring;
404: }
405:
406: ###############################
407:
408: =pod
409:
410: =item &get_debug()
411:
412: Inputs: none.
413:
414: Returns: A string describing the internal state of the lonmysql package.
415:
416: =cut
417:
418: ###############################
419: sub get_debug {
420: return $debugstring;
421: }
422:
423: ###############################
424:
425: =pod
426:
427: =item &update_table_info($table_id)
428:
429: Inputs: table id
430:
431: Returns: undef on error, 1 on success.
432:
433: &update_table_info updates the %Tables hash with current information about
434: the given table.
435:
436: The default MySQL table status fields are:
437:
438: Name Type Row_format
439: Max_data_length Index_length Data_free
440: Create_time Update_time Check_time
441: Avg_row_length Data_length Comment
442: Rows Auto_increment Create_options
443:
444: Additionally, "Col_order" is updated as well.
445:
446: =cut
447:
448: ###############################
449: sub update_table_info {
450: my ($table_id) = @_;
451: return undef if (! defined(&connect_to_db()));
452: my $table_status = &check_table($table_id);
453: return undef if (! defined($table_status));
454: if (! $table_status) {
455: $errorstring = "table $table_id does not exist.";
456: return undef;
457: }
458: my $tablename = &translate_id($table_id);
459: #
460: # Get MySQLs table status information.
461: #
462: my @tabledesc = qw/
463: Name Type Row_format Rows Avg_row_length Data_length
464: Max_data_length Index_length Data_free Auto_increment
465: Create_time Update_time Check_time Create_options Comment /;
466: my $db_command = "SHOW TABLE STATUS FROM loncapa LIKE '$tablename'";
467: my $sth = $dbh->prepare($db_command);
468: $sth->execute();
469: if ($sth->err) {
470: $errorstring = "$dbh ATTEMPTED:\n".$db_command."\nRESULTING ERROR:\n".
471: $sth->errstr;
472: &disconnect_from_db();
473: return undef;
474: }
475: #
476: my @info=$sth->fetchrow_array;
477: for (my $i=0;$i<= $#info ; $i++) {
478: $Tables{$tablename}->{$tabledesc[$i]}= $info[$i];
479: }
480: #
481: # Determine the column order
482: #
483: $db_command = "DESCRIBE $tablename";
484: $sth = $dbh->prepare($db_command);
485: $sth->execute();
486: if ($sth->err) {
487: $errorstring = "$dbh ATTEMPTED:\n".$db_command."\nRESULTING ERROR:\n".
488: $sth->errstr;
489: &disconnect_from_db();
490: return undef;
491: }
492: my $aref=$sth->fetchall_arrayref;
493: $Tables{$tablename}->{'Col_order'}=[]; # Clear values.
494: # The values we want are the 'Field' entries, the first column.
495: for (my $i=0;$i< @$aref ; $i++) {
496: push @{$Tables{$tablename}->{'Col_order'}},$aref->[$i]->[0];
497: }
498: #
499: $debugstring = "Retrieved table info for $tablename";
500: return 1;
501: }
502:
503: ###############################
504:
505: =pod
506:
507: =item &create_table
508:
509: Inputs:
510: table description
511:
512: Input formats:
513:
514: table description = {
515: permanent => 'yes' or 'no',
516: columns => {
517: colA => {
518: type => mysql type,
519: restrictions => 'NOT NULL' or empty,
520: primary_key => 'yes' or empty,
521: auto_inc => 'yes' or empty,
522: }
523: colB => { .. }
524: colZ => { .. }
525: },
526: column_order => [ colA, colB, ..., colZ],
527: }
528:
529: Returns:
530: undef on error, table id on success.
531:
532: =cut
533:
534: ###############################
535: sub create_table {
536: return undef if (!defined(&connect_to_db($dbh)));
537: my ($table_des)=@_;
538: #
539: # Build request to create table
540: ##################################
541: my @Columns;
542: my $col_des;
543: my $table_id = &get_new_table_id();
544: my $tablename = &translate_id($table_id);
545: my $request = "CREATE TABLE IF NOT EXISTS ".$tablename." ";
546: foreach my $column (@{$table_des->{'column_order'}}) {
547: $col_des = '';
548: my $coldata = $table_des->{'columns'}->{$column};
549: if (lc($coldata->{'type'}) =~ /(enum|set)/) { # 'enum' or 'set'
550: $col_des.=$column." ".$coldata->{'type'}."('".
551: join("', '",@{$coldata->{'values'}})."')";
552: } else {
553: $col_des.=$column." ".$coldata->{'type'};
554: if (exists($coldata->{'size'})) {
555: $col_des.="(".$coldata->{'size'}.")";
556: }
557: }
558: # Modifiers
559: if (exists($coldata->{'restrictions'})){
560: $col_des.=" ".$coldata->{'restrictions'};
561: }
562: if (exists($coldata->{'default'})) {
563: $col_des.=" DEFAULT '".$coldata->{'default'}."'";
564: }
565: $col_des.=' AUTO_INCREMENT' if (exists($coldata->{'auto_inc'}) &&
566: ($coldata->{'auto_inc'} eq 'yes'));
567: $col_des.=' PRIMARY KEY' if (exists($coldata->{'primary_key'}) &&
568: ($coldata->{'primary_key'} eq 'yes'));
569: } continue {
570: # skip blank items.
571: push (@Columns,$col_des) if ($col_des ne '');
572: }
573: if (exists($table_des->{'fulltext'}) && (@{$table_des->{'fulltext'}})) {
574: push (@Columns,'FULLTEXT ('.join(',',@{$table_des->{'fulltext'}}).')');
575: }
576: $request .= "(".join(", ",@Columns).") ";
577: unless($table_des->{'permanent'} eq 'yes') {
578: $request.="COMMENT = 'temporary' ";
579: }
580: $request .= "TYPE=MYISAM";
581: #
582: # Execute the request to create the table
583: #############################################
584: my $count = $dbh->do($request);
585: if (! defined($count)) {
586: $errorstring = "$dbh ATTEMPTED:\n".$request."\nRESULTING ERROR:\n";
587: return undef;
588: }
589: #
590: # Set up the internal bookkeeping
591: #############################################
592: delete($Tables{$tablename}) if (exists($Tables{$tablename}));
593: return undef if (! defined(&update_table_info($table_id)));
594: $debugstring = "Created table $tablename at time ".time.
595: " with request\n$request";
596: return $table_id;
597: }
598:
599: ###############################
600:
601: =pod
602:
603: =item &get_new_table_id
604:
605: Used internally to prevent table name collisions.
606:
607: =cut
608:
609: ###############################
610: sub get_new_table_id {
611: my $newid = 0;
612: my @tables = &tables_in_db();
613: foreach (@tables) {
614: if (/^$ENV{'user.name'}_$ENV{'user.domain'}_(\d+)$/) {
615: $newid = $1 if ($1 > $newid);
616: }
617: }
618: return ++$newid;
619: }
620:
621: ###############################
622:
623: =pod
624:
625: =item &get_rows
626:
627: Inputs: $table_id,$condition
628:
629: Returns: undef on error, an array ref to (array of) results on success.
630:
631: Internally, this function does a 'SELECT * FROM table WHERE $condition'.
632: $condition = 'id>0' will result in all rows where column 'id' has a value
633: greater than 0 being returned.
634:
635: =cut
636:
637: ###############################
638: sub get_rows {
639: my ($table_id,$condition) = @_;
640: return undef if (! defined(&connect_to_db()));
641: my $table_status = &check_table($table_id);
642: return undef if (! defined($table_status));
643: if (! $table_status) {
644: $errorstring = "table $table_id does not exist.";
645: return undef;
646: }
647: my $tablename = &translate_id($table_id);
648: my $request = 'SELECT * FROM '.$tablename.' WHERE '.$condition;
649: my $sth=$dbh->prepare($request);
650: $sth->execute();
651: if ($sth->err) {
652: $errorstring = "$dbh ATTEMPTED:\n".$request."\nRESULTING ERROR:\n".
653: $sth->errstr;
654: $debugstring = "Failed to get rows matching $condition";
655: return undef;
656: }
657: $debugstring = "Got rows matching $condition";
658: my @Results = @{$sth->fetchall_arrayref};
659: foreach my $row (@Results) {
660: for(my $i=0;$i<@$row;$i++) {
661: $row->[$i]=&Apache::lonnet::unescape($row->[$i]);
662: }
663: }
664: return @Results;
665: }
666:
667: ###############################
668:
669: =pod
670:
671: =item &store_row
672:
673: Inputs: table id, row data
674:
675: returns undef on error, 1 on success.
676:
677: =cut
678:
679: ###############################
680: sub store_row {
681: my ($table_id,$rowdata) = @_;
682: #
683: return undef if (! defined(&connect_to_db()));
684: my $table_status = &check_table($table_id);
685: return undef if (! defined($table_status));
686: if (! $table_status) {
687: $errorstring = "table $table_id does not exist.";
688: return undef;
689: }
690: #
691: my $tablename = &translate_id($table_id);
692: #
693: my $sth;
694: if (exists($Tables{$tablename}->{'row_insert_sth'})) {
695: $sth = $Tables{$tablename}->{'row_insert_sth'};
696: } else {
697: # Build the insert statement handler
698: return undef if (! defined(&update_table_info($table_id)));
699: my $insert_request = 'INSERT INTO '.$tablename.' VALUES(';
700: foreach (@{$Tables{$tablename}->{'Col_order'}}) {
701: $insert_request.="?,";
702: }
703: chop $insert_request;
704: $insert_request.=")";
705: $sth=$dbh->prepare($insert_request);
706: $Tables{$tablename}->{'row_insert_sth'}=$sth;
707: }
708: my @Parameters;
709: if (ref($rowdata) eq 'ARRAY') {
710: @Parameters = @$rowdata;
711: } elsif (ref($rowdata) eq 'HASH') {
712: foreach (@{$Tables{$tablename}->{'Col_order'}}) {
713: push(@Parameters,&Apache::lonnet::escape($rowdata->{$_}));
714: }
715: }
716: $sth->execute(@Parameters);
717: if ($sth->err) {
718: $errorstring = "$dbh ATTEMPTED insert @Parameters RESULTING ERROR:\n".
719: $sth->errstr;
720: return undef;
721: }
722: $debugstring = "Stored row.";
723: return 1;
724: }
725:
726: ###########################################
727:
728: =pod
729:
730: =item tables_in_db
731:
732: Returns a list containing the names of all the tables in the database.
733: Returns undef on error.
734:
735: =cut
736:
737: ###########################################
738: sub tables_in_db {
739: return undef if (!defined(&connect_to_db()));
740: my $sth=$dbh->prepare('SHOW TABLES');
741: $sth->execute();
742: if ($sth->err) {
743: $errorstring = "$dbh ATTEMPTED:\n".'SHOW TABLES'.
744: "\nRESULTING ERROR:\n".$sth->errstr;
745: return undef;
746: }
747: my $aref = $sth->fetchall_arrayref;
748: my @table_list=();
749: foreach (@$aref) {
750: push @table_list,$_->[0];
751: }
752: $debugstring = "Got list of tables in DB: @table_list";
753: return @table_list;
754: }
755:
756: ###########################################
757:
758: =pod
759:
760: =item &translate_id
761:
762: Used internally to translate a numeric table id into a MySQL table name.
763: If the input $id contains non-numeric characters it is assumed to have
764: already been translated.
765:
766: Checks are NOT performed to see if the table actually exists.
767:
768: =cut
769:
770: ###########################################
771: sub translate_id {
772: my $id = shift;
773: # id should be a digit. If it is not a digit we assume the given id
774: # is complete and does not need to be translated.
775: return $id if ($id =~ /\D/);
776: return $ENV{'user.name'}.'_'.$ENV{'user.domain'}.'_'.$id;
777: }
778:
779: ###########################################
780:
781: =pod
782:
783: =item &check_table($id)
784:
785: Checks to see if the requested table exists. Returns 0 (no), 1 (yes), or
786: undef (error).
787:
788: =cut
789:
790: ###########################################
791: sub check_table {
792: my $table_id = shift;
793: return undef if (!defined(&connect_to_db()));
794: #
795: $table_id = &translate_id($table_id);
796: my @Table_list = &tables_in_db();
797: my $result = 0;
798: foreach (@Table_list) {
799: if (/^$table_id$/) {
800: $result = 1;
801: last;
802: }
803: }
804: # If it does not exist, make sure we do not have it listed in %Tables
805: delete($Tables{$table_id}) if ((! $result) && exists($Tables{$table_id}));
806: $debugstring = "check_table returned $result for $table_id";
807: return $result;
808: }
809:
810: ###########################################
811:
812: =pod
813:
814: =item &remove_from_table($table_id,$column,$value)
815:
816: Executes a "delete from $tableid where $column like binary '$value'".
817:
818: =cut
819:
820: ###########################################
821: sub remove_from_table {
822: my ($table_id,$column,$value) = @_;
823: return undef if (!defined(&connect_to_db()));
824: #
825: $table_id = &translate_id($table_id);
826: my $command = 'DELETE FROM '.$table_id.' WHERE '.$dbh->quote($column).
827: " LIKE BINARY ".$dbh->quote($value);
828: my $sth = $dbh->prepare($command);
829: $sth->execute();
830: if ($sth->err) {
831: $errorstring = "ERROR on execution of ".$command."\n".$sth->errstr;
832: return undef;
833: }
834: my $rows = $sth->rows;
835: return $rows;
836: }
837:
838:
839: 1;
840:
841: __END__;
842:
843: =pod
844:
845: =back
846:
847: =cut
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