[mapserver-users] some questions regarding getFeatureInfo, SLD, PostGIS

[Julien Cigar]

On 09/21/2012 12:50, Rahkonen Jukka wrote:
> Hi,

Hello,

> So you have tried to define variables %SEX% and %BOD_ID%, used them inside your DATA and then fired  WMS GetMaps by adding&SEX=your_value&BOD_ID=your_id? Does in not work or why it is not powerful enough?

It is not powerful enough because it doesn't allow you to make simple 
logical tests (if defined/equals/...), the run-time substitution is a 
simple "replace %FOO%" by the value of FOO= from the query string.

It doesn't allow you to do something like: "if FOO is defined or equal 
to xxx, then add "JOIN foo f ON f.id = bar.foo_id", select additional 
columns, and add a "WHERE foo.id = ..." at a certain place in the DATA 
string".

I guess mapscript should be used in this case, but it would be really 
interesting to have this simple template language (or another solution) 
without having to involve mapscript.

Julien

> -Jukka Rahkonen-
>
>
> Julien Cigar wrote:
>
>> Hello,
>>
>> I'm using Mapserver 6.0.1 with the following PostGIS layer:
>> http://pastie.org/private/84042k84vmljbontls5xvq
>>
>> The user has the possibility to select quite a lot of filters, which implies that
>> the SQL query should, in theory ,be generated dynamically.
>> As this is not possible with Mapserver (run-time substitution with HTTP
>> parameters and VALIDATION ... END isn't powerful enough is my case), I'm
>> dynamically generating an SLD
>> (http://pastie.org/private/p66ml3uvqwcnphuuvera) to filter items and it
>> works very well.
>>
>> Some questions:
>>
>> - Why does Mapserver doesn't have a very lightweight template language (or
>> something similar) to dynamically build a string following given parameters? It
>> could be really useful to avoid unnecessary JOIN, etc.
>> For example something like:
>> http://pastie.org/private/bojm3pi1dwrv18m2tvq (this is just an example, but
>> the idea is there)
>>
>> - I noticed in the PostgreSQL logs that sometimes Mapserver adds an
>> additional condition to the WHERE clause when SLD is used. For example with
>> the following<ogc:Filter>  in my SLD:
>> #########################################
>> <ogc:Filter>
>> <ogc:PropertyIsEqualTo>
>> <ogc:PropertyName>basis_of_record_id</ogc:PropertyName>
>> <ogc:Literal>1</ogc:Literal>
>> </ogc:PropertyIsEqualTo>
>> </ogc:Filter>
>> #########################################
>>
>> Mapserver adds an additional "and (( ("basis_of_record_id"= 1) ))":
>>
>> (...) AS q where geom&&  GeomFromText('POLYGON((-3.6860351557368
>> -9.81732918571448,-3.6860351557368 9.81732918571447,47.6860351496117
>> 9.81732918571447,47.6860351496117 -9.81732918571448,-3.6860351557368
>> -9.81732918571448))',4326) and (( ("basis_of_record_id"= 1) ))
>>
>> which is not bad as less rows have to be post-processed by the SLD engine.
>>
>> However, as soon as I add an additional<ogc:or>  (or<ogc:and>) as:
>> #########################################
>> <ogc:or>
>> <ogc:PropertyIsEqualTo>
>> <ogc:PropertyName>basis_of_record_id</ogc:PropertyName>
>> <ogc:Literal>1</ogc:Literal>
>> </ogc:PropertyIsEqualTo>
>> <ogc:PropertyIsEqualTo>
>> <ogc:PropertyName>basis_of_record_id</ogc:PropertyName>
>> <ogc:Literal>2</ogc:Literal>
>> </ogc:PropertyIsEqualTo>
>> </ogc:or>
>> #########################################
>>
>> Mapserver doesn't add this additional AND/OR clause (and ((
>> ("basis_of_record_id"= 1) OR ("basis_of_record_id" = 2) )) in this case).. Why
>> ?
>>
>> - Is it normal that my SLD is totally ignored when I'm using
>> REQUEST=GetFeatureInfo? Is the SLD only processed with
>> REQUEST=GetMap?
>> If this is the case, what's the typical alternative way of doing it?
>> Should I go through WFS .. ?
>>
>> In advance, thank you for your answers :) Julien
>>
>> --
>> No trees were killed in the creation of this message.
>> However, many electrons were terribly inconvenienced.
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-- 
No trees were killed in the creation of this message.
However, many electrons were terribly inconvenienced.

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