1: # The LearningOnline Network with CAPA
2: # MySQL utility functions
3: #
4: # $Id: lonmysql.pm,v 1.7 2002/08/21 21:29:51 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: $debugstring = "Unable to connect to loncapa database.";
330: if (! defined($dbh)) {
331: $debugstring = "Unable to connect to loncapa database.";
332: $errorstring = "dbh was undefined.";
333: } elsif ($dbh->err) {
334: $errorstring = "Connection error: ".$dbh->errstr;
335: }
336: return undef;
337: }
338: $debugstring = "Successfully connected to loncapa database.";
339: return 1;
340: }
341:
342: ###############################
343:
344: =pod
345:
346: =item &disconnect_from_db()
347:
348: Inputs: none.
349:
350: Returns: Always returns 1.
351:
352: Severs the connection to the mysql database.
353:
354: =cut
355:
356: ###############################
357: sub disconnect_from_db {
358: foreach (keys(%Tables)) {
359: # Supposedly, having statement handlers running around after the
360: # database connection has been lost will cause trouble. So we
361: # kill them off just to be sure.
362: if (exists($Tables{$_}->{'row_insert_sth'})) {
363: delete($Tables{$_}->{'row_insert_sth'});
364: }
365: }
366: $dbh->disconnect if ($dbh);
367: $debugstring = "Disconnected from database.";
368: $dbh = undef;
369: return 1;
370: }
371:
372: ###############################
373:
374: =pod
375:
376: =item &number_of_rows()
377:
378: Input: table identifier
379:
380: Returns: the number of rows in the given table, undef on error.
381:
382: =cut
383:
384: ###############################
385: sub number_of_rows {
386: my ($table_id) = @_;
387: return undef if (! defined(&connect_to_db()));
388: return undef if (! defined(&update_table_info($table_id)));
389: return $Tables{&translate_id($table_id)}->{'Rows'};
390: }
391:
392: ###############################
393:
394: =pod
395:
396: =item &get_error()
397:
398: Inputs: none.
399:
400: Returns: The last error reported.
401:
402: =cut
403:
404: ###############################
405: sub get_error {
406: return $errorstring;
407: }
408:
409: ###############################
410:
411: =pod
412:
413: =item &get_debug()
414:
415: Inputs: none.
416:
417: Returns: A string describing the internal state of the lonmysql package.
418:
419: =cut
420:
421: ###############################
422: sub get_debug {
423: return $debugstring;
424: }
425:
426: ###############################
427:
428: =pod
429:
430: =item &update_table_info($table_id)
431:
432: Inputs: table id
433:
434: Returns: undef on error, 1 on success.
435:
436: &update_table_info updates the %Tables hash with current information about
437: the given table.
438:
439: The default MySQL table status fields are:
440:
441: Name Type Row_format
442: Max_data_length Index_length Data_free
443: Create_time Update_time Check_time
444: Avg_row_length Data_length Comment
445: Rows Auto_increment Create_options
446:
447: Additionally, "Col_order" is updated as well.
448:
449: =cut
450:
451: ###############################
452: sub update_table_info {
453: my ($table_id) = @_;
454: return undef if (! defined(&connect_to_db()));
455: my $table_status = &check_table($table_id);
456: return undef if (! defined($table_status));
457: if (! $table_status) {
458: $errorstring = "table $table_id does not exist.";
459: return undef;
460: }
461: my $tablename = &translate_id($table_id);
462: #
463: # Get MySQLs table status information.
464: #
465: my @tabledesc = qw/
466: Name Type Row_format Rows Avg_row_length Data_length
467: Max_data_length Index_length Data_free Auto_increment
468: Create_time Update_time Check_time Create_options Comment /;
469: my $db_command = "SHOW TABLE STATUS FROM loncapa LIKE '$tablename'";
470: my $sth = $dbh->prepare($db_command);
471: $sth->execute();
472: if ($sth->err) {
473: $errorstring = "$dbh ATTEMPTED:\n".$db_command."\nRESULTING ERROR:\n".
474: $sth->errstr;
475: &disconnect_from_db();
476: return undef;
477: }
478: #
479: my @info=$sth->fetchrow_array;
480: for (my $i=0;$i<= $#info ; $i++) {
481: $Tables{$tablename}->{$tabledesc[$i]}= $info[$i];
482: }
483: #
484: # Determine the column order
485: #
486: $db_command = "DESCRIBE $tablename";
487: $sth = $dbh->prepare($db_command);
488: $sth->execute();
489: if ($sth->err) {
490: $errorstring = "$dbh ATTEMPTED:\n".$db_command."\nRESULTING ERROR:\n".
491: $sth->errstr;
492: &disconnect_from_db();
493: return undef;
494: }
495: my $aref=$sth->fetchall_arrayref;
496: $Tables{$tablename}->{'Col_order'}=[]; # Clear values.
497: # The values we want are the 'Field' entries, the first column.
498: for (my $i=0;$i< @$aref ; $i++) {
499: push @{$Tables{$tablename}->{'Col_order'}},$aref->[$i]->[0];
500: }
501: #
502: $debugstring = "Retrieved table info for $tablename";
503: return 1;
504: }
505:
506: ###############################
507:
508: =pod
509:
510: =item &create_table
511:
512: Inputs:
513: table description
514:
515: Input formats:
516:
517: table description = {
518: permanent => 'yes' or 'no',
519: columns => {
520: colA => {
521: type => mysql type,
522: restrictions => 'NOT NULL' or empty,
523: primary_key => 'yes' or empty,
524: auto_inc => 'yes' or empty,
525: }
526: colB => { .. }
527: colZ => { .. }
528: },
529: column_order => [ colA, colB, ..., colZ],
530: }
531:
532: Returns:
533: undef on error, table id on success.
534:
535: =cut
536:
537: ###############################
538: sub create_table {
539: return undef if (!defined(&connect_to_db($dbh)));
540: my ($table_des)=@_;
541: #
542: # Build request to create table
543: ##################################
544: my @Columns;
545: my $col_des;
546: my $table_id = &get_new_table_id();
547: my $tablename = &translate_id($table_id);
548: my $request = "CREATE TABLE IF NOT EXISTS ".$tablename." ";
549: foreach my $column (@{$table_des->{'column_order'}}) {
550: $col_des = '';
551: my $coldata = $table_des->{'columns'}->{$column};
552: if (lc($coldata->{'type'}) =~ /(enum|set)/) { # 'enum' or 'set'
553: $col_des.=$column." ".$coldata->{'type'}."('".
554: join("', '",@{$coldata->{'values'}})."')";
555: } else {
556: $col_des.=$column." ".$coldata->{'type'};
557: if (exists($coldata->{'size'})) {
558: $col_des.="(".$coldata->{'size'}.")";
559: }
560: }
561: # Modifiers
562: if (exists($coldata->{'restrictions'})){
563: $col_des.=" ".$coldata->{'restrictions'};
564: }
565: if (exists($coldata->{'default'})) {
566: $col_des.=" DEFAULT '".$coldata->{'default'}."'";
567: }
568: $col_des.=' AUTO_INCREMENT' if (exists($coldata->{'auto_inc'}) &&
569: ($coldata->{'auto_inc'} eq 'yes'));
570: $col_des.=' PRIMARY KEY' if (exists($coldata->{'primary_key'}) &&
571: ($coldata->{'primary_key'} eq 'yes'));
572: } continue {
573: # skip blank items.
574: push (@Columns,$col_des) if ($col_des ne '');
575: }
576: if (exists($table_des->{'fulltext'}) && (@{$table_des->{'fulltext'}})) {
577: push (@Columns,'FULLTEXT ('.join(',',@{$table_des->{'fulltext'}}).')');
578: }
579: $request .= "(".join(", ",@Columns).") ";
580: unless($table_des->{'permanent'} eq 'yes') {
581: $request.="COMMENT = 'temporary' ";
582: }
583: $request .= "TYPE=MYISAM";
584: #
585: # Execute the request to create the table
586: #############################################
587: my $count = $dbh->do($request);
588: if (! defined($count)) {
589: $errorstring = "$dbh ATTEMPTED:\n".$request."\nRESULTING ERROR:\n";
590: return undef;
591: }
592: #
593: # Set up the internal bookkeeping
594: #############################################
595: delete($Tables{$tablename}) if (exists($Tables{$tablename}));
596: return undef if (! defined(&update_table_info($table_id)));
597: $debugstring = "Created table $tablename at time ".time.
598: " with request\n$request";
599: return $table_id;
600: }
601:
602: ###############################
603:
604: =pod
605:
606: =item &get_new_table_id
607:
608: Used internally to prevent table name collisions.
609:
610: =cut
611:
612: ###############################
613: sub get_new_table_id {
614: my $newid = 0;
615: my @tables = &tables_in_db();
616: foreach (@tables) {
617: if (/^$ENV{'user.name'}_$ENV{'user.domain'}_(\d+)$/) {
618: $newid = $1 if ($1 > $newid);
619: }
620: }
621: return ++$newid;
622: }
623:
624: ###############################
625:
626: =pod
627:
628: =item &get_rows
629:
630: Inputs: $table_id,$condition
631:
632: Returns: undef on error, an array ref to (array of) results on success.
633:
634: Internally, this function does a 'SELECT * FROM table WHERE $condition'.
635: $condition = 'id>0' will result in all rows where column 'id' has a value
636: greater than 0 being returned.
637:
638: =cut
639:
640: ###############################
641: sub get_rows {
642: my ($table_id,$condition) = @_;
643: return undef if (! defined(&connect_to_db()));
644: my $table_status = &check_table($table_id);
645: return undef if (! defined($table_status));
646: if (! $table_status) {
647: $errorstring = "table $table_id does not exist.";
648: return undef;
649: }
650: my $tablename = &translate_id($table_id);
651: my $request = 'SELECT * FROM '.$tablename.' WHERE '.$condition;
652: my $sth=$dbh->prepare($request);
653: $sth->execute();
654: if ($sth->err) {
655: $errorstring = "$dbh ATTEMPTED:\n".$request."\nRESULTING ERROR:\n".
656: $sth->errstr;
657: $debugstring = "Failed to get rows matching $condition";
658: return undef;
659: }
660: $debugstring = "Got rows matching $condition";
661: my @Results = @{$sth->fetchall_arrayref};
662: return @Results;
663: }
664:
665: ###############################
666:
667: =pod
668:
669: =item &store_row
670:
671: Inputs: table id, row data
672:
673: returns undef on error, 1 on success.
674:
675: =cut
676:
677: ###############################
678: sub store_row {
679: my ($table_id,$rowdata) = @_;
680: #
681: return undef if (! defined(&connect_to_db()));
682: my $table_status = &check_table($table_id);
683: return undef if (! defined($table_status));
684: if (! $table_status) {
685: $errorstring = "table $table_id does not exist.";
686: return undef;
687: }
688: #
689: my $tablename = &translate_id($table_id);
690: #
691: my $sth;
692: if (exists($Tables{$tablename}->{'row_insert_sth'})) {
693: $sth = $Tables{$tablename}->{'row_insert_sth'};
694: } else {
695: # Build the insert statement handler
696: return undef if (! defined(&update_table_info($table_id)));
697: my $insert_request = 'INSERT INTO '.$tablename.' VALUES(';
698: foreach (@{$Tables{$tablename}->{'Col_order'}}) {
699: $insert_request.="?,";
700: }
701: chop $insert_request;
702: $insert_request.=")";
703: $sth=$dbh->prepare($insert_request);
704: $Tables{$tablename}->{'row_insert_sth'}=$sth;
705: }
706: my @Parameters;
707: if (ref($rowdata) eq 'ARRAY') {
708: @Parameters = @$rowdata;
709: } elsif (ref($rowdata) eq 'HASH') {
710: foreach (@{$Tables{$tablename}->{'Col_order'}}) {
711: push(@Parameters,$rowdata->{$_});
712: }
713: }
714: $sth->execute(@Parameters);
715: if ($sth->err) {
716: $errorstring = "$dbh ATTEMPTED insert @Parameters RESULTING ERROR:\n".
717: $sth->errstr;
718: return undef;
719: }
720: $debugstring = "Stored row.";
721: return 1;
722: }
723:
724: ###########################################
725:
726: =pod
727:
728: =item tables_in_db
729:
730: Returns a list containing the names of all the tables in the database.
731: Returns undef on error.
732:
733: =cut
734:
735: ###########################################
736: sub tables_in_db {
737: return undef if (!defined(&connect_to_db()));
738: my $sth=$dbh->prepare('SHOW TABLES');
739: $sth->execute();
740: if ($sth->err) {
741: $errorstring = "$dbh ATTEMPTED:\n".'SHOW TABLES'.
742: "\nRESULTING ERROR:\n".$sth->errstr;
743: return undef;
744: }
745: my $aref = $sth->fetchall_arrayref;
746: my @table_list=();
747: foreach (@$aref) {
748: push @table_list,$_->[0];
749: }
750: $debugstring = "Got list of tables in DB: @table_list";
751: return @table_list;
752: }
753:
754: ###########################################
755:
756: =pod
757:
758: =item &translate_id
759:
760: Used internally to translate a numeric table id into a MySQL table name.
761: If the input $id contains non-numeric characters it is assumed to have
762: already been translated.
763:
764: Checks are NOT performed to see if the table actually exists.
765:
766: =cut
767:
768: ###########################################
769: sub translate_id {
770: my $id = shift;
771: # id should be a digit. If it is not a digit we assume the given id
772: # is complete and does not need to be translated.
773: return $id if ($id =~ /\D/);
774: return $ENV{'user.name'}.'_'.$ENV{'user.domain'}.'_'.$id;
775: }
776:
777: ###########################################
778:
779: =pod
780:
781: =item &check_table($id)
782:
783: Checks to see if the requested table exists. Returns 0 (no), 1 (yes), or
784: undef (error).
785:
786: =cut
787:
788: ###########################################
789: sub check_table {
790: my $table_id = shift;
791: return undef if (!defined(&connect_to_db()));
792: #
793: $table_id = &translate_id($table_id);
794: my @Table_list = &tables_in_db();
795: my $result = 0;
796: foreach (@Table_list) {
797: if (/^$table_id$/) {
798: $result = 1;
799: last;
800: }
801: }
802: # If it does not exist, make sure we do not have it listed in %Tables
803: delete($Tables{$table_id}) if ((! $result) && exists($Tables{$table_id}));
804: $debugstring = "check_table returned $result for $table_id";
805: return $result;
806: }
807:
808: ###########################################
809:
810: =pod
811:
812: =item &remove_from_table($table_id,$column,$value)
813:
814: Executes a "delete from $tableid where $column like binary '$value'".
815:
816: =cut
817:
818: ###########################################
819: sub remove_from_table {
820: my ($table_id,$column,$value) = @_;
821: return undef if (!defined(&connect_to_db()));
822: #
823: $table_id = &translate_id($table_id);
824: my $command = 'DELETE FROM '.$table_id.' WHERE '.$dbh->quote($column).
825: " LIKE BINARY ".$dbh->quote($value);
826: my $sth = $dbh->prepare($command);
827: $sth->execute();
828: if ($sth->err) {
829: $errorstring = "ERROR on execution of ".$command."\n".$sth->errstr;
830: return undef;
831: }
832: my $rows = $sth->rows;
833: return $rows;
834: }
835:
836:
837: 1;
838:
839: __END__;
840:
841: =pod
842:
843: =back
844:
845: =cut
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