Categories
JavaScript

Delayed javascript function/handler gets the right variable/parameter values

So we have a function that adds a handler function that is called after an ajax load or at a later time and we need to execute the handler function code for each item inside an array allowing the function to access the array values. Usually with the simplest try you would get some code that get’s executed with invalid variable values. Examples are below.

The wrong code:

//the function that will do the stuff for each array
var dostuff = function (arr) {
var n = arr.length,
    i;
    for(i = 0; i < n; i++) {
        var o = arr[i];
        //event bind or delayed function call
        setTimeout(function () {
                //we want to access here the correct arr[i]
                //when the code gets here the value of o is arr[arr.length-1]
                console.log(o);
        }, 1000);
    }
}
dostuff([1,2,3,4]);

You can load the code into your javascript console to see it in action.
The output appears after 1 second and it is like this:

4
4
4
4

I don't need that. I need something that works so we need to wrap the handler call into a function call that will pass the current values as parameters.

var dostuff = function (arr) {
var n = arr.length,
    i;
    for(i = 0; i < n; i++) {
        var o = arr[i];
        (function (y) {
            setTimeout(function () {
                console.log(y);
            }, 1000);
        }) (o);
    }
}
dostuff([1,2,3,4]);

The output appears after 1 second and it is like this:

1
2
3
4

The final best solution would be to have the function inside for already defined so you don't define it on every loop:

var dostuff_item = function (y) {
            setTimeout(function () {
                console.log(y);
         }, 1000);
 }
var dostuff = function (arr) {
var n = arr.length,
    i;
    for(i = 0; i < n; i++) {
        var o = arr[i];
        dostuff_item (o);
    }
}
dostuff([1,2,3,4]);

Tada!

Categories
MySQL

Updating multiple fields in multiple rows with different values in a single query in MySQL using the CASE operator does not supply a correct result

Suppose we have a table with rows representing nodes of a tree structure, each node being represented by an id, a parent id and a position between the children of its parent node:

CREATE TABLE  `tree`.`node` (
`idnode` TINYINT NOT NULL AUTO_INCREMENT ,
`idnode_parent` TINYINT NULL ,
`position` TINYINT NULL ,
PRIMARY KEY ( `idnode` )
);

The nodes with idnode_parent set to 0 or NULL are on the first level of the tree structure.

Now we populate the table:

#add some first level nodes
INSERT INTO `tree`.`node` VALUES (NULL, 0, 1); #idnode = 1
INSERT INTO `tree`.`node` VALUES (NULL, 0, 2); #idnode = 2
#add some children for the first node on the first level
INSERT INTO `tree`.`node` VALUES (NULL, 1, 1); #idnode = 3
INSERT INTO `tree`.`node` VALUES (NULL, 1, 2); #idnode = 4
#add some children for the node with idnode 2
INSERT INTO `tree`.`node` VALUES (NULL, 2, 1); #idnode = 5
INSERT INTO `tree`.`node` VALUES (NULL, 2, 2); #idnode = 6
INSERT INTO `tree`.`node` VALUES (NULL, 2, 3); #idnode = 7
#add a child for the node with idnode 7
INSERT INTO `tree`.`node` VALUES (NULL, 7, 1); #idnode = 8

Now the table looks like this:
idnode idnode_parent position
1 0 1
2 0 2
3 1 1
4 1 2
5 2 1
6 2 2
7 2 3
8 3 1
9 7 1

We want to delete:
– node 1, so we move its children (3, 4) up one level (idnode_parent changes from 1 to 0) and update their positions to the position of their parent (position changes from 1, 2 respectively to 1);
– node 7, so we move its children (8) up one level (idnode_parent changes from 7 to 2) and update their positions to the position of their parent (position changes from 1 to 3)

a) We try this query:

UPDATE node
SET idnode_parent = CASE(idnode_parent)
WHEN 1 THEN 0
WHEN 7 THEN 2
END,
position = CASE(idnode_parent)
WHEN 1 THEN 1
WHEN 7 THEN 3
END
WHERE idnode_parent IN (1, 7);

Running this query, MySQL says 3 rows were affectedand the table looks as follows:

idnode idnode_parent position
1 0 1
2 0 2
3 0 NULL
4 0 NULL
5 2 1
6 2 2
7 2 3
8 3 1
9 2 NULL

We can see that only the field idnode_parent updated as expected, the position field for the moved nodes being set to NULL.

b) We reset the table to the initial test data and we run the above query with the difference of using the ELSE clause in the CASE expression:

UPDATE node
SET idnode_parent = CASE(idnode_parent)
WHEN 1 THEN 0
WHEN 7 THEN 2
ELSE idnode_parent
END,
position = CASE(idnode_parent)
WHEN 1 THEN 1
WHEN 7 THEN 3
ELSE position
END
WHERE idnode_parent IN (1, 7);

The result is:

idnode idnode_parent position
1 0 1
2 0 2
3 0 1
4 0 2
5 2 1
6 2 2
7 2 3
8 3 1
9 2 1

So the idnode_parent field updates correctly, but position remains unchanged.

My conclusion is that that the query runs as if there were two different queries running over the bunch of rows resulted after evaluating the WHERE condition, the second CASE operator applying over the data modified by the first CASE operator:
1. WHERE condition is evaluated; resulted data set:

idnode idnode_parent position
3 1 1
4 1 2
9 7 1

2. idnode_parent is set by evaluating the first CASE expression:

idnode idnode_parent position
3 0 1
4 0 2
9 2 1
3. position is set by evaluating the second CASE expression:

a) Using the query without the ELSE condition, position is set to NULL for all the rows in the data set, as after running the first CASE expression there are no more rows with the idnode_parent needed for the second CASE expression:
idnode idnode_parent position
3 0 NULL
4 0 NULL
9 2 NULL

b) Using the query with the ELSE condition, position remains unchanged for all the rows in the data set, as there are no more rows with the needed idnode_parent, as they were modified by applying the previous CASE operator, and the ELSE condition is evaluated:
idnode idnode_parent position
3 0 1
4 0 2
9 2 1

So if we want the query to run correctly, we set the position first, and then the id of the parent node, as position does not modify data needed for subsequent idnode_parent updates in the same query:

UPDATE node
SET position = CASE(idnode_parent)
WHEN 1 THEN 1
WHEN 7 THEN 3
END,
idnode_parent = CASE(idnode_parent)
WHEN 1 THEN 0
WHEN 7 THEN 2
END
WHERE idnode_parent IN (1, 7);

We finally obtain the expected result:
idnode idnode_parent position
3 0 1
4 0 1
9 2 3

Categories
Uncategorized

NTLDR is missing

Problem: Computer with Windows XP Professional operation system froze unexpectedly. No recent hardware changes performed, no applications recently installed. I reeboted. “NTLDR is missing” error occured.

I noticed that the system did not detect the hard disk drive where the operating system resided but I fixed this by reseating the IDE cables. Though the error persisted.

I then inserted the Windows XP boot CD in the CD-ROM drive in order to repair the operaton system. But I realized that if I changed in BIOS the Primary Boot Device from Hard Disk to CD-ROM, when the system asked if I wanted to boot from CD, I should not press any key and the system booted from Hard Disk. But this only happend if a bootable Windows XP CD was in the CD-ROM Drive.

While searching the Internet for solutions to this problem, i found this article.
No need for me to make a bootable anything as this guy describes here, but something caught my eye:

Once back into Windows, right click on the My Computer option, choose the Manage option. The Computer Management window will open, click on “Disk Management” on the left pane. One of the disks it lists, and one of the drives on it, will need to be marked as active. It will be which drive letter you have placed the 3 boot files into (this will likely be the C: drive on Disk 0). Right click on that drive letter and select “Mark Partition as Active”, you may first have to convert the partition to a Primary partition before you can mark it as active. Close and reboot.

I noticed that in Disk Management it was marked as active a partition on a slave hard disk. I wanted to unmark it, but I realized that I could not do that from the Disk Management interface.
Reading on the mentioned article, I found the solution to this last occured problem:
Mark Partition as Active with diskpart from Jim the Bean

I did that and it worked. It not only solved the active partition problem, but also my bigger problem as the system reebooted just fine with the Primary Boot Device set to Hard Disk and there was no need to set any partition as active on my system.

Categories
How to PHP

How to convert server date and time to the local date and time taking into account daylight saving time

‘Many countries, or even parts of countries, adopt daylight saving time (DST, also known as “Summer Time”) during part of the year. This typically involves advancing clocks by an hour near the start of spring and adjusting back in autumn (“spring” forward, “fall” back).’ (see Wikipedia)

Now I will demonstrate how we can convert a server date and time to the corresponding date and time in another timezone in Europe, taking Romania as example.

‘All countries in Europe except Iceland observe DST, and most change on the same date and time, starting on the last Sunday in March and ending on the last Sunday in October.’
‘In the West European (UTC), Central European (CET, UTC+1), and East European (UTC+2) time zones the change is simultaneous: on both dates the clocks are changed everywhere at 01:00 UTC, i.e. from local times of 01:00/02:00/03:00 to 02:00/03:00/04:00 in March, and vice versa in October.’ (see Wikipedia)

Romania is a country in the Eastern Europe, which falls under the East European Time (EET) also known as UTC+2 time zone and uses Eastern European Summer Time (UTC+3) as a summer daylight saving time.

The next function will be used to find out the offset in hours from UTC (GMT) of a local date and time of Romania or another region that switches between DST and standard time on the same date and time as Romania (is the local date and time in DST or in standard time?)

function local_offset_from_utc($timestamp, $standard_offset)
//$timestamp - the timestamp of the server date and time we want to convert to local date and time
//$standard_offset - the offset from UTC of the local date and time when observing the standard time; in daylight saving time the offset is $standard_offset + 1
{
	$year = gmdate("Y", $timestamp); //get the UTC year of the given date and time
//get the date to 'spring forward'
	$mar_31_utc_ts = gmmktime(0, 0, 0, 4, 0, $year); //the UTC timestamp of March 31, the last day of March, equivalent to gmmktime(0, 0, 0, 3, 31, $year)
	$last_sun_mar = 31 - gmdate("w", $mar_31_utc_ts); //the day of the month under which falls the last Sunday in March
	$spring_ts = gmmktime(1, 0, 0, 3, $last_sun_mar, $year); //the timestamp of the last Sunday in March 01:00 UTC
//get the date to 'fall back'
	$oct_31_utc_ts = gmmktime(0, 0, 0, 11, 0, $year); //the UTC timestamp of October 31, the last day of October, equivalent to gmmktime(0, 0, 0, 10, 31, $year)
	$last_sun_oct = 31 - gmdate("w", $oct_31_utc_ts); //the day of the month under which falls the last Sunday in October
	$fall_ts = gmmktime(1, 0, 0, 10, $last_sun_oct, $year); //the timestamp of the last Sunday in October, 01:00 UTC
	if($timestamp >= $spring_ts && $timestamp < $fall_ts) //daylight saving time
	{
		return $standard_offset + 1;
	}
//standard time
	return $standard_offset;
}

If the server switches between DST and standard time simultaneously with your timezone, you can simply use date("I") to find out if your local date and time is in daylight saving time or standard time:

if(date("I", $timestamp) == 1)
{
	$offset = $standard_offset + 1;
}
else
{
	$offset = $standard_offset;
}

Be careful with that, because a sever don't always switch between DST and standard time at the same hour as the timezone it has set, for example my server switches from DST to standard time at 03:00 UTC+3, which becomes 02:00 UTC+2, when it should go from 04:00 UTC+3 to 03:00 UTC+2). So I better use the function above that works not caring if or when the timezone of the server switches between DST and standard time.

If an offset of a timezone from UTC is negative, then the UTC date and time is greater than the corresponding date and time in the considered timezone; if the offset is positive then the UTC date and time is lower than the corresponding date and time in the considered timezone. If we consider t being the date and time in a given timezone, utc being the corresponding UTC date and time and offset being the offset of the given timezone from UTC, then we have:

t = utc + offset
utc = t - offset

So if we consider t1 being a server date and time and o1 being the offset of the timezone of the server from UTC (in hours) and t2 being the local date and time and o2 being the offset of the timezone of the server from UTC (in hours) we have:

utc = t1 - o1
t2 = utc + o2 = t1 - o1 + o2

In practice we only have a server date and time which we convert to timestamp ts1 based on which we find out the timestamp ts2 when the date and time in the timezone of the server equaled/will equal to the local date and time corresponding to ts1:

ts2 = ts1 - os1 + os2, where os1 = o1 * 60 *60 seconds and os2 = o2 * 60 *60 seconds

E.g. Let's consider the timezone of the server date and time is UTC-5 and Romania is in standard time (has an offset of 2 hours from UTC).

The UTC date and time that corresponds to the given timestamp equals to the server date and time that was/will be 5 hours later than the given timestamp:

ts_aux = ts1 - (-5 * 3600) = ts1 + 5 * 3600

The local date and time of Romania corresponding to the given timestamp equals to the UTC date and time that was/will be 2 hours later than the UTC date and time computed above:

ts2 = ts_aux + 2 * 3600 = ts1 + (5 + 2) * 3600 = ts1 + 7 * 3600

But this is NOT true if the server time and date that equals the needed local date and time falls under DST and the original server date falls under standard time or vice versa, which means that the offsets from UTC of the two server dates are different by 1 hour.

For example, if the server we considered before is in UTC-5 DST and goes back one hour on the first of November at 03:00:00 local server time and we want to see what Romania local date and time corresponds to the server date and time November 1st 01:00:00, then, applying the formula above, we will obtain a timstamp that corresponds to the server date and time November 1st 07:00:00 which should correspond to the local Romania time for the original server time, but the correct Romania date and time being November 1st 08:00:00. That is because, between November 1st 01:00:00 and November 1st 07:00:00, the server goes back one hour so that 03:00:00 DST becomes 02:00:00 standard time and 08:00:00 becomes 07:00:00, while the Romania time does not, Romania switching to DST one week earlier, so the correct formula in this case is:

ts2 = ts1 - os1 + os2 + 3600
ts2 = ts1 + (5 + 2 + 1) * 3600 = ts1 + 8 * 3600

Similarly, if the server switches from standard time to DST between the two dates, the formula becomes:

ts2 = ts1 - os1 + os2 - 3600
ts2 = ts1 + (5 + 2 - 1) * 3600 = ts1 + 6 * 3600

The next function is used to determine what the timestamp was/will be in the timezone of the server when the server date and time equaled/will be equal to the needed local date and time.

function get_timestamp_for_local($date = "", $standard_offset = 2)
{
	if(!empty($date))
	{
		$timestamp = strtotime($date);
	}
	else
	{
		$timestamp = time();
	}
	$os1 = date("Z", $timestamp);
	$os2 = local_offset_from_utc($timestamp, $standard_offset) * 3600;
	$ts = $timestamp - $os1 + $os2;
	//check the offset from UTC of the server date and time that equal the needed local date and time
	$os3 = date("Z", $ts);
	if($os3 == $os1) //the two server dates are both in DST or both in standard time
	{
		return $ts;
	}
	elseif($os3 > $os1) //the server date and time that equal the needed local date and time are in DST and the original server date and time are in standard time
	{
		return $ts - 3600;
	}
 	//the server date and time that equal the needed local date and time are in standard time and the original server date and time are in DST
	return $ts + 3600;
}

And finally we get the needed date and time:

function get_ro_date($date)
{
	return date("d.m.Y H:i:s", get_timestamp_for_local($date));
}

Next l will show how we can convert a server date and time to the corresponding date and time in another timezone in North America, taking the State of Washington as example.

'North America generally follows the same procedure, with each time zone switching at 02:00 LST (local standard time) to 03:00 LDT (local daylight time) on the second Sunday in March, and back from 02:00 LDT to 01:00 LST on the first Sunday in November since 2007.'
In the United States of America, 'the start of DST now occurs on the second Sunday in March and ends on the first Sunday in November.' (see Wikipedia)

The State of Washington falls under the Pacific Time Zone (PT), which is Pacific Standard Time (PST) or UTC-8 when observing standard time and Pacific Daylight Time (PDT) or UTC-7 during daylight saving time.

So we have to change the previous local_offset_from_utc function to find out the offset in hours from UTC (GMT) of a local date and time of Washington:

function local_offset_from_utc2($timestamp, $standard_offset, $spring_forward_hour, $fall_back_hour)
//$timestamp - the timestamp of the server date and time we want to convert to local date and time
//$standard_offset - the offset from UTC of the local date and time when observing the standard time; in daylight saving time the offset is $standard_offset + 1
//$spring_forward_hour - the hour of the local time when switching to DST
//$fall_back_hour - the hour of the local time when switching to standard time
{
//find out the year of the local date and time corresponding to the given server date and time, based on the corresponding UTC date and time
	$year = gmdate("Y", $timestamp); //UTC year of the given server date and time
	if($standard_offset < 0) //local timezone is behind UTC
	{
		//if the given sever date and time corresponds to January the 1st in UTC and the UTC hour is lower than the absolute value of the offset of the local time from UTC, then the corresponding local date and time falls in the year previous to the UTC year
		$month = gmdate("n", $timestamp);
		if($month == 1)
		{
			$day = gmdate("j", $timestamp);
			if($day == 1)
			{
				$hour = gmdate("G", $timestamp);
				if($hour + $standard_offset < 0)
				{
					$year -= 1;
				}
			}
		}
	}
	else //local timezone time is ahead of UTC
	{
		//if the given sever date and time corresponds to December 31 in UTC and the sum of UTC hour and the offset of the local time from UTC is greater than 24, then the corresponding local date and time falls in the year subsequent to the UTC year
		$month = gmdate("n", $timestamp);
		if($month == 12)
		{
			$day = gmdate("j", $timestamp);
			if($day == 31)
			{
				$hour = gmdate("G", $timestamp);
				if($hour + $standard_offset > 24)
				{
					$year += 1;
				}
			}
		}
	}
	//get the date to 'spring forward'
	$mar_1_utc_ts = gmmktime(0, 0, 0, 3, 1, $year); //the timestamp for the UTC time of March the 1st, 00:00:00
	$mar_1_day_of_week = gmdate("w", $mar_1_utc_ts);
	//compute the day of the month under which falls the second Sunday in March
	if($mar_1_day_of_week > 0) //the day of the week of the 1st of March is not Sunday
	{
		$second_sun_mar = 15 - $mar_1_day_of_week;
	}
	else
	{
		$second_sun_mar = 8;
	}
	$spring_local_ts = gmmktime($spring_forward_hour - $standard_offset, 0, 0, 3, $second_sun_mar, $year);
	//get the date to 'fall back'
	$nov_1_utc_ts = gmmktime(0, 0, 0, 11, 1, $year); //the timestamp for the UTC time of November the 1st, 00:00:00
	$nov_1_day_of_week = gmdate("w", $nov_1_utc_ts);
//compute the day of the month under which falls the first Sunday in November
	if($nov_1_day_of_week > 0) //the day of the week of the 1st of November is not Sunday
	{
		$first_sun_nov = 8 - $nov_1_day_of_week;
	}
	else
	{
		$first_sun_nov = 1;
	}
	$fall_local_ts = gmmktime($fall_back_hour - ($standard_offset + 1), 0, 0, 11, $first_sun_nov, $year);
	if($timestamp >= $spring_local_ts && $timestamp < $fall_local_ts) //daylight saving time
	{
		return $standard_offset + 1;
	}
	//standard time
	return $standard_offset;
}

The function get_timestamp_for_local remains the same, only we add 2 more paramters to it which will be needed when calling the function:

function get_timestamp_for_local2($date = "", $standard_offset = -8, $spring_forward_hour = 2, $fall_back_hour = 3)
{
	if(!empty($date))
	{
		$timestamp = strtotime($date);
	}
	else
	{
		$timestamp = time();
	}
	$os1 = date("Z", $timestamp);
	$os2 = local_offset_from_utc2($timestamp, $standard_offset, $spring_forward_hour, $fall_back_hour) * 3600;
	$ts = $timestamp - $os1 + $os2;
	//check the offset from UTC of the server date and time that equal the needed local date and time
	$os3 = date("Z", $ts);
	if($os3 == $os1) //the two dates are both in DST or both in standard time
	{
		return $ts;
	}
	elseif($os3 > $os1) //the server date and time that equal the needed local date and time are in DST and the original server date and time are in standard time
	{
		return $ts - 3600;
	}
	//the server date and time that equal the needed local date and time are in standard time and the original server date and time are in DST
	return $ts + 3600;
}

And now we can find out the date and time in the State of Washington that corresponds to the given server date and time:

function get_wa_date($date)
{
	return date("Y-m-d H:i:s", get_timestamp_for_local2($date));
}
Categories
Apache Web Server PHP

SoftException in Application.cpp:544: Directory “/path/dir” is writeable by group

Full error message: SoftException in Application.cpp:544: Directory “/path/to/directory” is writeable by group

The error apeared in cpanel logs at a hosting company and was related to a directory I created via ftp and where I tried to run some php script. When accessing the script from the web browser i got the error “500 Internal Server Error”

The problem is that Apache 2.0 server doesn’t allow in some cases (i don’t know these cases yet) that the directories created with write access rights set to all unless it’s set by the same unix user as the user running apache process. In order to fix this we need to create the folder from the same user as apache user. To do this we need to create the folder or to change the access rights from php.

The fix is to upload a small php file with the following code:

<?php
chmod("./dir", 0755);
?>

After we set the access right on “dir” to 777 we run the  php script then the error should not appear anymore.

Categories
How to

How to recover a hard deleted store folder in Microsoft Outlook Express 6

It happened for several times that I accidentally hard deleted a store folder in Microsoft Outlook Express 6 when trying to delete an email in that folder (both the folder and the e-mail looked like being selected, but it seems that the focus was on the folder and not the e-mail as I expected).

Seems that when we access (select) for the first time a store folder, say “MyFolder”, we created in Outlook Express, a .dbx file is automatically created in the Outlook Express Mail directory “C:\Documents and Settings\<username>\Local Settings\Application Data\Identities\{<identity-code>}\Microsoft\Outlook Express”.
If it doesn’t already exist a file named MyFolder.dbx in the OE Mail directory, such a file is created and a refernce from the store folder “MyFolder” to this .dbx file is created in the Folder.dbx file in the OE Mail directory.
If there already is a .dbx file in The OE Mail directory with the same name as the folder we created (MyFolder.dbx), then, when we access the folder “MyFolder”, it will be created a .dbx file named MyFolder(1).dbx, if does not already exist a file named MyFolder(1).dbx in the OE Mail directory, otherwise a file named MyFolder(2).dbx will be created etc. Also a reference from “MyFolder” to the newly created .dbx file is created in the Folders.dbx file.

To see which .dbx file is associated with a certain store folder in Outlook Express, right click on that folder and select Properties; under the General tab you’ll find the full path to the .dbx file the folder is stored in.

When we delete a store folder in Outlook Express, only the reference to the .dbx file is deleted, the .dbx file remaining orphan. So, if we want to recover the deleted folder, a new folder and a reference between it and the orphaned .dbx file should be created. This is how you do that:

1. Move, not copy, the orphaned .dbx file from OE Mail directory to another location.
Do not just copy the file elsewhere because if there already is a .dbx file with the same name as the folder you create, say MyFolder.dbx, then when you select the newly created folder it will be created a .dbx file named like MyFolder(1).dbx as explained before.

2. In Outlook Express, create a folder with exactlty the same name (case sensitive) as the orphaned .dbx file, select the newly created folder so that a new .dbx file is automatically created (this should have the same name as the orphaned .dbx file), close OE.

3. Overwrite the new (empty) .dbx file in your OE Mail directory with the orphaned file and open OE.

4. If you had any mail message rules involving the deleted folder, repair them, because OE deletes the references to the folder from the message rules once you delete a folder, but it does not remake them once you remake the folder (go to Tools -> Messages rules -> Mail).

Categories
PHP

When submitting a PHP form, the script does not stop

If you submit a PHP form which passes a large amount of data using the POST method, like a file upload form, it would be a good idea to increase the value of the PHP configuration variable post_max_size (you will find it in the php.ini file) if it seems like the script is running forever. post_max_size should be set to a value larger than the maximum sum of the sizes of the files the script is used to upload.

Categories
Apache Web Server MySQL PHP

Importing a MySQL data file using phpMyAdmin results in incomplete data in MySQL

I tried moving all my databases from MySQL 4.1 to MySQL 5.1 on Windows and since I had some InnoDB tables I could not just copy the data files between MySQL Server versions (from C:\Documents and Settings\All Users\Application Data\MySQL\MySQL 4.1\data\ to  C:\Documents and Settings\All Users\Application Data\MySQL\MySQL 5.1\data\).
So, after I exported the data from the old MySQL Server version I tried importing it to the MySQL 5.1 using phpMyAdmin.
The file to import was 42MB in size, so I had to set some PHP configuration variables (in php.ini file) to greater values:

post_max_size = 64M
upload_max_filesize = 64M

At first it looked like the phpMyAdmin import script entered a loop or something, as it wouldn’t stop even after running for several minutes and, as I was looking into the data files it was producing, no new files appeared. It was like it blocked on a table with a large number of records, which didn’t make any sense. Then I restarted the Apache server and I tried the import all over again. The same thing was happening. I finally decided to let it run for more time and the script finally stopped. But the data imported was incomplete; a part of the records in the large table I thought script blocked on, and every table and database from there on were missing, with no PHP or MySQL error returned.
Then I thought the script needed even more time to run, so I increased the value of the PHP configuration variable max_execution_time, but with the same result.

The solution. It seems that the execution time limit for the import script in phpMyAdmin is defined by the variable $cfg[‘ExecTimeLimit’] in <path_to_phpMyAdmin>/libraries/config.default.php and the value of this variable should be a lot greater than its default value of 300 seconds when importing a great amount of data. In my case it needed about an hour (3600 seconds) to complete. So you have to set this variable depending on the amount of data you are importing.
You might also need to set the MySQL configuration variable max_allowed_packet (in my case, in C:\Program Files\MySQL\MySQL Server 5.1\my.ini) to a greater value, if you have large queries in the data file you want to import, for avoiding MySQL error 2006, ‘mysql server has gone away’.

Categories
Firefox HTML Internet Explorer JavaScript

base html tag does not apply correctly to all javascript and style files

Problem: The 

<base href="http://example.com/path/to/res/">

  did not work at all on Internet Explorer – no javascript or style files were loaded and worked partially in Mozilla Firefox – a few javascript files were not pointing to the path that should be transformed by base href attribute.

Example:

Array(
[0] => 1
)
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<base href="http://example.com/path/to/res/">
<link rel="stylesheet" href="./css/styles.css" type="text/css" />
<scrupt src="./js/jquery.js" type="text/javascript"></script>
<scrupt src="./js/j1.js" type="text/javascript"></script>
<scrupt src="./js/j2.js" type="text/javascript"></script>

This code produced a page with no style files and  no javascript files included in Interenet Explorer 8 and a few javascript files (j1.js and j2.js) were not included in Firefox 3.5 because base tag was not applied. After several tests and all kind of different arrangements we discovered that the problem was the output before the page source the 

Array ...

thing.

Solution: no output before the page’s headers otherwise you can get all kind of strange results including a html base tag not working correctly.

Categories
Internet Explorer JavaScript

Object doesn’t support property or method. Adding options in a <select> from a child window on Internet Explorer

Full error message:  Object doesn’t support property or method. I got this error message in Internet Explorer 7 every time i tried to run code similar to the next snippet:

window.opener.form.select[select.length]  = new Option(text, value);

The problem is that on Internet Explorer due to some mysterious security restrictions you are not allowed to add new options in a select element that resides in the parent (opener) window. In order to do this you need a workaround.

The easiest workaround is to write a function in the parent window that adds elements in the select element. The function should look something like this:

function addOptionToSelect(formName, selectName, optionText, optionValue) {
var elem = document.forms[formName].elements[selectName];
elem.options[elem.length] = new Option(optionText, optionValue);
}

This function has to be written in the parent window’s javascript and it will be accessed from child window with some code like this:

window.opener.addOptionToSelect(formName, selectName, optionText, optioValue);

Conclusion: Internet Explorer sucks.