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MDL-35155 database: better sql_substr() impl. for mssql/sqlsrv + unit tests

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MSSQL's substring() implementation is somehow silly/strict and unable to
perform implicit casts to integer both for the start and length parameters.

This hits Moodle badly because of another problems (MDL-23997) we decided
to cast to string all bound placeholders long ago.

So this commit just enforces the cast of the start and length parameters to
integer. And includes unit tests for using placeholders on all positions in
the sql_substr() method.
This commit is contained in:
Eloy Lafuente (stronk7) 2015-01-12 18:17:36 +01:00 committed by Dan Poltawski
parent 933c8f6a25
commit 5d98ba68f5
3 changed files with 28 additions and 7 deletions
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4
lib/dml/mssql_native_moodle_database.php
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@ -1257,9 +1257,9 @@ class mssql_native_moodle_database extends moodle_database {
s only returning name of SQL substring function, it now requires all parameters.');
}
if ($length === false) {
return "SUBSTRING($expr, $start, LEN($expr))";
return "SUBSTRING($expr, " . $this->sql_cast_char2int($start) . ", 2^31-1)";
} else {
return "SUBSTRING($expr, $start, $length)";
return "SUBSTRING($expr, " . $this->sql_cast_char2int($start) . ", " . $this->sql_cast_char2int($length) . ")";
}
}

4
lib/dml/sqlsrv_native_moodle_database.php
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@ -1324,9 +1324,9 @@ class sqlsrv_native_moodle_database extends moodle_database {
}
if ($length === false) {
return "SUBSTRING($expr, $start, LEN($expr))";
return "SUBSTRING($expr, " . $this->sql_cast_char2int($start) . ", 2^31-1)";
} else {
return "SUBSTRING($expr, $start, $length)";
return "SUBSTRING($expr, " . $this->sql_cast_char2int($start) . ", " . $this->sql_cast_char2int($length) . ")";
}
}

27
lib/dml/tests/dml_test.php
View File

@ -4027,9 +4027,30 @@ class core_dml_testcase extends database_driver_testcase {
$this->assertInstanceOf('coding_exception', $e);
}
$sql = "SELECT id, ".$DB->sql_substr("name", ":param1 + 1")." AS name FROM {{$tablename}}";
$record = $DB->get_record_sql($sql, array('param1' => 4));
$this->assertEquals(substr($string, 5-1), $record->name);
// Cover the function using placeholders in all positions.
$start = 4;
$length = 2;
// 1st param (target).
$sql = "SELECT id, ".$DB->sql_substr(":param1", $start)." AS name FROM {{$tablename}}";
$record = $DB->get_record_sql($sql, array('param1' => $string));
$this->assertEquals(substr($string, $start - 1), $record->name); // PHP's substr is 0-based.
// 2nd param (start).
$sql = "SELECT id, ".$DB->sql_substr("name", ":param1")." AS name FROM {{$tablename}}";
$record = $DB->get_record_sql($sql, array('param1' => $start));
$this->assertEquals(substr($string, $start - 1), $record->name); // PHP's substr is 0-based.
// 3rd param (length).
$sql = "SELECT id, ".$DB->sql_substr("name", $start, ":param1")." AS name FROM {{$tablename}}";
$record = $DB->get_record_sql($sql, array('param1' => $length));
$this->assertEquals(substr($string, $start - 1, $length), $record->name); // PHP's substr is 0-based.
// All together.
$sql = "SELECT id, ".$DB->sql_substr(":param1", ":param2", ":param3")." AS name FROM {{$tablename}}";
$record = $DB->get_record_sql($sql, array('param1' => $string, 'param2' => $start, 'param3' => $length));
$this->assertEquals(substr($string, $start - 1, $length), $record->name); // PHP's substr is 0-based.
// Try also with some expression passed.
$sql = "SELECT id, ".$DB->sql_substr("name", "(:param1 + 1) - 1")." AS name FROM {{$tablename}}";
$record = $DB->get_record_sql($sql, array('param1' => $start));
$this->assertEquals(substr($string, $start - 1), $record->name); // PHP's substr is 0-based.
}
public function test_sql_length() {