[mapserver-users] querying in mode=tile

[Richard Greenwood]

On Sun, Sep 11, 2011 at 8:48 AM, Mr. Puneet Kishor <punk.kish at gmail.com> wrote:
>
> On Sep 11, 2011, at 8:03 AM, Richard Greenwood wrote:
>
>> On Sat, Sep 10, 2011 at 1:35 PM, Mr. Puneet Kishor <punk.kish at gmail.com> wrote:
>>> Now that I have mode=tile working with Google Maps API v3, I am on my way to implement querying like so
>>>
>>>    0. Bind an infowindow.close() to a click event listener on the map
>>>    1. Bind an infowindow.open() to a click event listener on the MapServer layer
>>>    2. Fill the infowindow content with the result from an Ajax query to MapServer
>>>    3. When the user clicks on the MapServer layer, the Ajax query is fired
>>>    4. MapServer responds with the query result as a JSON object
>>>    5. Fill the infowindow with the JSON result
>>>    6. Close any already open infowindow via #0 above
>>>    7. Open a new infowindow with the result
>>>
>>> Is the general approach outlined above sound? Any pointers to existing code samples for the above?
>>
>>
>> Puneet,
>>
>> I'm doing pretty much that here:
>>   http://records.sublettewyo.com/mapserver/map.html
>> I'm using jQuery in this example and putting the info into a jQuery
>> dialog, however I have used a standard browser window in the past.
>> Only thing is that I don't thinnk you really need step 0, simply
>> replace the contents of the container with the new info.
>
>
> Yup, I don't have to worry about #0. Howerver, #1 above is problematic, and I don't have a resolution for it yet. Seems like in Google Maps API v3 I can't addListener to an ImageMapType overlay. See, I am adding a MapServer layer as ImageMapType overlay like so
>
>  "mapserverLayer" : new google.maps.ImageMapType({ .. })
>  map.overlayMapTypes.insertAt(0, mapserverLayer);
>
>
> If I do the following --
>
>  google.maps.event.addListener(map, "click", function (event) { }
>
> it works, however, the following doesn't work at all
>
>  google.maps.event.addListener(mapserverLayer, "click", function (event) { }
>
> Which is silly, isn't it? I don't want the entire map to be listening to the "click" events. I just want the MapServer layer to be doing so. Haven't yet found a resolution to this.
>
>
>>
>> Also, if your data is in PostGIS you can skip mapserver for attribute
>> queries and do an info query against the PostGIS db via PHP or other
>> server-side tool.
>>
>
> Ok, I am very interested in the above, but I am not sure I understand you. For the most part, I want to click on the map, and find out more about what I clicked on. In order to do that query via Perl MapScript (I don't know PHP) and Pg, I would need to create the $mapObj. I am able to do that fine, but I don't know how to run MapServer in `mode=tile` via MapScript. This is the question I have asked a couple of times -- if I have a pure MapScript app (no map files involved at all, which is what I want), how no earth do I tell the app to use `mode=tile`?
>
> Puneet.
>
>

Puneet,

I do not know how to bind an infowindow.open() to a click event
listener on the MapServer layer (#1 above) because I do not use the
Google API. But using Perl, PHP or whatever it is easy to query a
PostGIS database, and even get GeoJSON back should you want to
highlight the selected object on the map.

I am using OpenLayers so I can easily convert the mouse click (or box)
to a real-world coordinate(s). I pass the point or box to a PHP page
which connects to a PostGIS db, does the query, and returns JSON. Does
that help? I'm not sure that I understand everything that you're doing
and maybe my approach is not appropriate in your case.

Are you in Denver for FOSS4G??

Rich

-- 
Richard Greenwood
richard.greenwood at gmail.com
www.greenwoodmap.com