[Geomoose-users] using WFS-T

[Brent Fraser]

Hey Eli,

   The filtering is for visual purposes: since images from different 
dates may be in the same location I want to see only those polygons 
related to the image being shown.

   My particular use-case is such that there will never be very many 
polygons served via WFS at once. but I do have some performance concerns 
in general.  Fortunately Geomoose/OpenLayers sends a bounding box filter 
based on the display window so that will tend to minimize the problem.

   I've hard-coded an OpenLayers attribute filter in WFS.js for testing 
purposes:

         this._ol_layer = new OpenLayers.Layer.Vector(this.title, {
             strategies: strategies,
             projection: this.srsName,
             styleMap : this.style_map,
             visibility: false,
*            filter: new OpenLayers.Filter.Comparison({         //BWF**
**                type: OpenLayers.Filter.Comparison.EQUAL_TO,**
**                property: "image_id",**
**                value: "204"**
**            }),**
**            proto*col: new OpenLayers.Protocol.WFS({
                 version: '1.1.0',
                 srsName: this.srsName,
                 url: this.url,
                 featureNS: this.featureNS,
                 featurePrefix: this.featurePrefix,
                 featureType: this.featureType,
                 geometryName: this.featureGeometryName,
                 schema: this.featureSchema
             })
         });

and it works fine (the above code causes only those polygons digitized 
from image 204 to be shown).  Now I need to hack in some code to change 
the filter value when the user selects a different image.  While it will 
be ok for my project, it would be nice to come up with a more general 
approach.  Maybe I'll get some inspiration while hacking...

Best Regards,
Brent Fraser

On 3/15/2016 5:57 PM, Eli Adam wrote:
> Hi Brent,
>
>
> On Tue, Mar 15, 2016 at 7:38 AM, Brent Fraser <bfraser at geoanalytic.com> wrote:
>> Hi All,
>>
>>    Now that I've configured my Geomoose demo to do WFS-T, I need to think
>> about how to use it in my old Geomoose v2.4  Ice Digitizing application.
> Cool, good to hear that it is working.
>
>>    That application grouped digitized polygons by "image_id" (representing
>> the Landsat image used as a backdrop).  There are hundreds of images and
>> thousands of polygons in the system and when the user selected an image,
>> Geomoose passed the image_id to mapserver to do a substitution in the
>> mapfile SQL so only those polygons related to that image were displayed (and
>> available for edits etc).  That worked great.
> Is filtering for visual purposes so that you can see what is going on?
>   Or is filtering for performance and browser limits?  Did you try
> solution 0 which is to do no filtering and see if it works?
>
>
>> How do I do the same thing with Geomoose v2.8 for my app?  Some possible
>> "solutions" (I like #3):
>>
>> 1.  Convert the old 2.4 vector editing system to a user extension and use it
>> instead of WFS-T
>>          - a lot of work, uses deprecated code, and no benefit to the
>> Geomoose community
>> or
>>
>> 2. Create a layer per image_id in the TingyOWS config.xml file and have
>> Geomoose switch layer name when the user selects the image.
>>      - as images get added to the system the config.xml file must be updated
>> (could be automated, but clunky)
>>      - each layer would point to a table in the database which would make the
>> database ugly
>> (hundreds of tables).  I might be able to use views instead of tables to
>> make it slightly less ugly, but TinyOWS might not do inserts into a view.
>> Dunno about that.
>>      - could be some limitations on the number of layers in the config.xml
>> file (or performance issues?).
>>
>> or
>>
>> 3.  Add functionality to Geomoose to accept attribute filters in the mapbook
>> and pass the filters to the OpenLayers definition.
>>      - adds complexity to the mapbook syntax (so more documentation, testing,
>> maint., etc).
>>      - the logic may be similar to the  mapbook's search/query mechanism of
>> specifying input types of layer,template,fieldname,comparitor,value so maybe
>> some of the code could be used.
> This sounds like an option worth exploring and may have other general
> applicaitons.
>
>> or
>>
>> 4.  Other?
> My ideas are sort of light on this one, hopefully others have further ideas.
>
> Best regards, Eli
>
>> Thanks for any input!
>>
>> --
>> Best Regards,
>> Brent Fraser
>>
>>
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>> Geomoose-users at lists.osgeo.org
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