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You know you can use CQL to create GeoTools Filter used when filtering FeatureCollection. GeoTools 16 user guide has made a quick tutorial and examples for CQL strings like the following ones:

ATTR1 >= 5
NCLUDE
EXCLUDE
ATTR1 < (1 + ((2 / 3) * 4))
(ATTR1 + ATTR2) > 0.07
ATTR1 < abs(ATTR2)
ATTR1 < 10 AND ATTR2 < 2 OR ATTR3 > 10
ATTR1 LIKE 'abc%'
ATTR1 NOT LIKE 'abc%'
ATTR1 BETWEEN 10 AND 20
ATTR1 IS NULL
ATTR1 IS NOT NULL
ATTR1 DOES-NOT-EXIST     // check if something does not exist

string functions:

strToLowerCase(ATTR1) like '%m%'

collections:

ATTR1 IN ('New York', 'California', 'Montana', 'Texas')
IN ('states.1', 'states.12')       // with specific feature ids

date time:

ATTR1 TEQUALS 2006-11-30T01:30:00Z                       // equal to a date
ATTR1 BEFORE 2006-11-30T01:30:00Z                        // before a date
ATTR1 BEFORE 2006-11-30T01:30:00Z/2006-12-31T01:30:00Z   // before a period
ATTR1 AFTER 2006-11-30T01:30:00Z                         // after a date
ATTR1 AFTER 2006-11-30T01:30:00+03:00                    // after a date using time zone GMT+3
ATTR1 AFTER 2006-11-30T01:30:00Z/2006-12-31T01:30:00Z    // after a period

geometry:

CONTAINS(ATTR1, POINT(1 2))
BBOX(ATTR1, 10,20,30,40)
DWITHIN(ATTR1, POINT(1 2), 10, kilometers)
CROSS(ATTR1, LINESTRING(1 2, 10 15))
INTERSECT(ATTR1, GEOMETRYCOLLECTION (POINT (10 10),POINT (30 30),LINESTRING (15 15, 20 20)) )
CROSSES(ATTR1, LINESTRING(1 2, 10 15))
INTERSECTS(ATTR1, GEOMETRYCOLLECTION (POINT (10 10),POINT (30 30),LINESTRING (15 15, 20 20)) )

full list of geometric predicates (from geoserver guide ):

EQUALS, DISJOINT, INTERSECTS, TOUCHES, CROSSES, WITHIN, CONTAINS,
OVERLAPS, RELATE, DWITHIN, BEYOND

examples are usefull but I couldn't find any full tutorial about syntax, structure, functions, math functions, etc. Can anyone introduce a full guide for CQL.


udig tutorial:

uding guide for CQL

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The CQL is defined by the OGC as part of the catalogue service (i.e. CSW) model specification. See http://docs.opengeospatial.org/is/12-168r6/12-168r6.html for the current (as of July 2016) version. GeoTools claims support for 2.0.1, which you can find linked off http://www.opengeospatial.org/standards/cat in the deprecated spec section.

For the GeoTools specific part, there is design documentation in the source repo at https://github.com/geotools/geotools/blob/master/modules/library/cql/CQL.md and of course, you can review the source any time :-)

Note that the language is extensible, so if you are working GeoTools / GeoServer (or uDig) then you can use the GeoTools ECQL extensions: http://docs.geotools.org/latest/userguide/library/cql/ecql.html (note design document linkage off that page, or see https://github.com/geotools/geotools/blob/master/modules/library/cql/ECQL.md)

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