[Mapserver-users] Class Expression help

[Nick Petersen-Bergeron]

Unquoting the entire expression produces an expression parser error.

At 01:08 PM 7/17/2003 -0300, you wrote:
>El jue, 17 de 07 de 2003 a las 12:22, Nick Petersen-Bergeron escribió:
>>
>>As a followup, when I quote the column name, I get the error:
>>Thu Jul 17 11:29:04 2003 - msEvalExpression(): General error message.
>>Cannot evaluate expression, no item index defined.
>>
>>While this error seems more pertinent, an Item Index shouldn't be necessary
>>should it?
>
>
>The whole expression shouldn't been unquoted?
>
><SIC> EXPRESSION [string] Three types of expressions are now supported to 
>define class membership. String comparisons, regular expressions, and 
>simple logical expressions. If no expression is given, then all features 
>are said to belong to this class.
>String comparisons are case sensitive and are the fastest to evaluate. No 
>special delimiters are necessary although string must be quoted if they 
>contain special characters. (As a matter of good habit, it is recommended 
>you quote all strings).
>
>Regular expressions function just like previous versions of MapServer. 
>However, you must now delimit a regular expression using /regex/. No 
>quotes should be used.
>
>Logical expressions allow you to build fairly complex tests based on one 
>or more attributes and therefore are only available with shapefiles. 
>Logical expressions are delimited by parentheses "(expression)". Attribute 
>names are delimited by square brackets "[ATTRIBUTE]". These names are case 
>sensitive and must match the items in the shapefile. For example: 
>EXPRESSION ([POPULATION] > 50000 AND '[LANGUAGE]' eq 'FRENCH') ... The 
>following logical operators are supported : 
>=,>,<,<=,>=,=,or,and,lt,gt,ge,le,eq. As you might expect this level of 
>complexity is slower to process.
>String comparisons and regular expressions work from the classitem defined 
>at the layer level. You may mix expression types within the different 
>classes of a layer.
>
></SIC>
>
>
>
>
>>
>>
>>
>>
>>At 05:01 PM 7/17/2003 +0200, Vincent Schut wrote:
>> >Nick,
>> >jsut a guess, but have you tried it with [LEVEL] and [DAY] single 
>> quoted too?
>> >I think you always need to quote your attribute column names.
>> >
>> >Regards,
>> >Vincent.
>> >
>> >On Thursday 17 July 2003 16:50, Nick Petersen-Bergeron wrote:
>> > > I'm trying to do a class based layer structure for a map program I'm
>> > > writing.  I've looked through all of the syntax examples for expressions
>> > > that I can find, but can't seem to figure out what's wrong.
>> > >
>> > > I have around 20 classes in the layer.  Essentially the only thing that
>> > > will differ between classes is the color.
>> > >
>> > > I've included an example of one of the classes.
>> > >
>> > > CLASS
>> > >                  EXPRESSION "(('[TEMP]' eq 'normal') AND ('[PRECIP]' eq
>> > > 'normal') AND ([LEVEL] eq 0) AND ([DAY] eq 30))"
>> > >                  COLOR 50 50 50
>> > >                  SIZE 5
>> > >                  NAME "normal_city"
>> > >                  SYMBOL "circle"
>> > >                  LABEL
>> > >                          COLOR 50 50 50
>> > >                          FONT arial
>> > >                          SIZE 12
>> > >                          POSITION ur
>> > >                          ANTIALIAS TRUE
>> > >                          TYPE TRUETYPE
>> > >                  END
>> > >          END
>> > >
>> > > Can anyone see a problem with this?
>> > >
>> > > When I comment out a single expression, the shapefile I'm using 
>> defaults to
>> > > using that class, so I'm guessing that none of the expressions are
>> > > evaluating to true.  However, the dbf for the shape seems to 
>> indicate that
>> > > this should not be the case.  The only error being thrown is the 
>> following:
>> > >
>> > >
>> > > Thu Jul 17 10:41:37 2003 - msSearchDiskTree(): Unable to access file.
>> > > Unable to open spatial index for /home/wcs/html/data/countries2.qix. In
>> > > most cases you can safely ignore this message, otherwise check file 
>> names
>> > > and permissions.
>> > >
>> > >
>> > > Thanks for your help.
>>
>>Nick Petersen-Bergeron
>>System Administrator
>>
>>ZedX Inc.
>>369 Rolling Ridge Drive
>>Bellefonte, PA. 16823
>>
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>
>Nick Petersen-Bergeron
>System Administrator
>
>ZedX Inc.
>369 Rolling Ridge Drive
>Bellefonte, PA. 16823