Ben Mearns

Monday, November 10, 2008

create dom html with php, getelementbyid doesn't work

I leverage the domdocument php class to create elegant, dynamic html documents via the dom tree. However, I was finding that the "getelementbyid" method was not returning elements as expected. The reason for this is that I had not defined a DTD, which is necessary in this case because we only specify that we are saving as HTML at the end of the process, so the domdocument object is only understood as generic XML, which has no predefined "id." To create a DTD use this code (here using 4.01 transitional html):

$doc = new DOMDocument();
$doc->loadHTML('<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">;');

there are so many options with pear's db library for php, I sometimes forget the optimal code for getting a sql result as an array that I can easily use within php. The code below fully demonstrates connecting to and getting an associative array with an 'order by' field as the array key. This code is for a postgres rdms, but could easily be modified for mysql, sqlserver, etc. Parameters are in caps surrounded by '%' in the form %PARAMETER%.

require_once 'DB.php';

$dsn = "pgsql://%LOGIN%:%PASSWORD%@%HOST%/%DBNAME%";
$dbh =& DB::connect ($dsn);
if (PEAR::isError($dbh)) {
die($dbh->getMessage());
}

$dbh->setFetchMode(DB_FETCHMODE_ASSOC);
$res =& $dbh->getAssoc('%SQL STATEMENT, USE 'ORDER BY' TO DEFINE ARRAY KEY%');

if (PEAR::isError($res)) {
die($res->getMessage());
}

Tuesday, September 30, 2008

When defining projection from ArcCatalog (shapefile properties) I get an error message "Failed to Alter the Spatial Reference". If I try to do this from the "Define Projection" geoprocessing tool (ArcToolbox) I get this error insted: "Cannot create a projection file for filepath Failed to execute (DefineProjection).

I solved this problem by accesing the shapefile through a mapped drive (a.k.a. "Z:\") within ArcCatalog, rather than its \\server\drive$ pathname.

Friday, September 19, 2008

There are multiple caching levels to be mindful of with a typical ArcGIS Server environment. This factor often makes debugging difficult. Below I have made an expanding list of issues related to cahcing as well as the various cache levels to clear when debugging.

Issues related to caching: query does not return correct field as defined in 'outFields' query property

Cache Levels

AGS web service cache, this can be cleared by restarting the AGS web service from ArcCatalog or by web admin interface
Tile cache, cleared by 'deleting cache', and then reconfiguring tile cache within service properties of the web service
Web browser cache, cleared by clearing cache of web browser
REST API cache, cleared by going to http://yourserveraddress/ArcGIS/rest/admin/cache and clearing cache manually
KML cache, if using a Google hosted KML with your application, to have this load dynamically you need to add a random number to the end of your kml address ... google it!

Wednesday, September 17, 2008

To do a non-boolean conditional insert in SQL Server (the "where exists" clause is best for boolean), use the "where in" clause along with an inner join, in the following form:

INSERT INTO [Destination Table]([Destination Field1],[Destination Field2],[...])
SELECT [Origin Field1],[Origin Field2],[...]
FROM [Origin Table]
WHERE ([Test Field A, could be from origin] Not In (select [Test Field B] from
[Test Table, could be destination]));

Monday, August 18, 2008

Gmaps: GEvent and "a is not defined"

I was getting the (generic and fairly common) "a is not defined" (on line 287 of main.js I believe) javascript error with gmaps when trying to add a GEvent click event listener. I intially thought it was an issue with my some map layers with ArcGIS Javascript Extension for Google Maps, but I resolved this issue by sticking the even handler in the initialize function. For some reason gmaps must not have been available at the scope of the even handler outside this function ... the gmap object was being instantiated inside this function, yet the variable was first declared outside the function in the first lines of the application ... strange.

Thursday, August 14, 2008

Flash Map Workflow, described

Thematic groups created in ArcMap and enhanced with Adobe Illustrator (AI), were saved as separate AI files (by region) and further organized as AI “layers.” Note that a layer should be created for every group of shapes which would be always dealt with in the same way in an animation. For example, if a group of lines would appear and disappear together and never separately, they should be organized into a layer. These layers later correspond to symbols in the Flash application. All layers were then selected and copied/pasted into Flash at once. Flash has the ability to implicitly import AI layers as Flash layers copied and pasted into it. Note that the “paste in place” command should be used in order to guarantee uniform positioning across layers copied/pasted from different AI files -- the dimensions of the Flash canvas must be the same as the AI document for this to work.

The Flash Actionscript program then deals with all user interaction and data display. Symbols are displayed/not displayed, fade in/out, or are magnified based on program functions referencing the symbols indicated by other user interface symbols (buttons, etc.) which are invoked by user interaction.