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###############################################################################
# #
# CAST(... AS LINESTRING) allows casting geometries of type #
# LINESTRING, POLYGON, MULTIPOINT, MULTILINESTRING and GEOMETRYCOLLECTION #
# to type LINESTRING. #
# #
# Creation Date: 2020-08-02 #
# Author: Magnus Rushfeldt #
# #
###############################################################################
--echo ############################################
--echo # Requirement F-8a: #
--echo # CAST(linestring AS LINESTRING) #
--echo ############################################
--echo #
--echo # Casting from LINESTRING to LINESTRING is always allowed.
--echo # Must return Linestring.
SELECT ST_ASTEXT(CAST(ST_GEOMFROMTEXT('LINESTRING(1 1, 2 2)') AS LINESTRING));
--echo # Must return 1.
SELECT ST_EQUALS(ST_GEOMFROMTEXT('LINESTRING(1 1, 2 2)'), CAST(ST_GEOMFROMTEXT('LINESTRING(1 1, 2 2)') AS LINESTRING));
--echo #
--echo #
--echo ############################################
--echo # Requirement F-8b: #
--echo # CAST(polygon AS LINESTRING) #
--echo ############################################
--echo #
--echo # Casting from POLYGON with only exterior ring to LINESTRING is allowed.
--echo # Must return Linestring.
SELECT ST_ASTEXT(CAST(ST_GEOMFROMTEXT('POLYGON((1 1, 2 2, 3 3, 1 1))') AS LINESTRING));
--echo # Must return 1.
SELECT ST_EQUALS(ST_GEOMFROMTEXT('LINESTRING(1 1, 2 2, 3 3, 1 1)'), CAST(ST_GEOMFROMTEXT('POLYGON((1 1, 2 2, 3 3, 1 1))') AS LINESTRING));
--echo #
--echo # Casting from POLYGON with multiple rings to LINESTRING is not allowed.
--echo # Must raise error.
--error ER_INVALID_CAST_TO_GEOMETRY
DO ST_ASTEXT(CAST(ST_GEOMFROMTEXT('POLYGON((1 1, 2 2, 3 3, 1 1), (4 4, 5 5, 6 6, 4 4))') AS LINESTRING));
--echo #
--echo ############################################
--echo # Requirement F-8c: #
--echo # CAST(multipoint AS LINESTRING) #
--echo ############################################
--echo #
--echo # Casting from MULTIPOINT with two or more points to LINESTRING is allowed.
--echo # Must return Linestring.
SELECT ST_ASTEXT(CAST(ST_GEOMFROMTEXT('MULTIPOINT((1 1), (2 2))') AS LINESTRING));
--echo # Must return 1.
SELECT ST_EQUALS(ST_GEOMFROMTEXT('LINESTRING(1 1, 2 2)'), CAST(ST_GEOMFROMTEXT('MULTIPOINT((1 1), (2 2))') AS LINESTRING));
--echo #
--echo # Casting from MULTIPOINT with only one point to LINESTRING is not allowed.
--echo # Must raise error.
--error ER_INVALID_CAST_TO_GEOMETRY
DO ST_ASTEXT(CAST(ST_GEOMFROMTEXT('MULTIPOINT((1 1))') AS LINESTRING));
--echo #
--echo ############################################
--echo # Requirement F-8d: #
--echo # CAST(multilinestring AS LINESTRING) #
--echo ############################################
--echo #
--echo # Casting from MULTILINESTRING with only one Linestring to LINESTRING is allowed.
--echo # Must return Linestring.
SELECT ST_ASTEXT(CAST(ST_GEOMFROMTEXT('MULTILINESTRING((1 1, 2 2))') AS LINESTRING));
--echo # Must return 1.
SELECT ST_EQUALS(ST_GEOMFROMTEXT('LINESTRING(1 1, 2 2)'), CAST(ST_GEOMFROMTEXT('MULTILINESTRING((1 1, 2 2))') AS LINESTRING));
--echo #
--echo # Casting from MULTILINESTRING with multiple Linestrings to LINESTRING is not allowed.
--echo # Must raise error.
--error ER_INVALID_CAST_TO_GEOMETRY
DO ST_ASTEXT(CAST(ST_GEOMFROMTEXT('MULTILINESTRING((1 1, 2 2), (3 3, 4 4))') AS LINESTRING));
--echo #
--echo ############################################
--echo # Requirement F-8e: #
--echo # CAST(geometrycollection AS LINESTRING) #
--echo ############################################
--echo #
--echo # Casting from GEOMETRYCOLLECTION with only one Linestring to LINESTRING is allowed.
--echo # Must return Linestring.
SELECT ST_ASTEXT(CAST(ST_GEOMFROMTEXT('GEOMETRYCOLLECTION(LINESTRING(1 1, 2 2))') AS LINESTRING));
--echo # Must return 1.
SELECT ST_EQUALS(ST_GEOMFROMTEXT('LINESTRING(1 1, 2 2)'), CAST(ST_GEOMFROMTEXT('GEOMETRYCOLLECTION(LINESTRING(1 1, 2 2))') AS LINESTRING));
--echo #
--echo # Casting from empty GEOMETRYCOLLECTION to LINESTRING is not allowed.
--echo # Must raise error.
--error ER_INVALID_CAST_TO_GEOMETRY
DO ST_ASTEXT(CAST(ST_GEOMFROMTEXT('GEOMETRYCOLLECTION()') AS LINESTRING));
--echo #
--echo # Casting from GEOMETRYCOLLECTION with multiple Linestrings to LINESTRING is not allowed.
--echo # Must raise error.
--error ER_INVALID_CAST_TO_GEOMETRY
DO ST_ASTEXT(CAST(ST_GEOMFROMTEXT('GEOMETRYCOLLECTION(LINESTRING(1 1, 2 2), LINESTRING(3 3, 4 4))') AS LINESTRING));
--echo #
--echo # Casting from GEOMETRYCOLLECTION with other geometries than Linestrings to LINESTRING is not allowed.
--echo # Must raise error.
--error ER_INVALID_CAST_TO_GEOMETRY
DO ST_ASTEXT(CAST(ST_GEOMFROMTEXT('GEOMETRYCOLLECTION(LINESTRING(1 1, 2 2), GEOMETRYCOLLECTION())') AS LINESTRING));
--echo #
--echo ############################################
--echo # Requirement F-8d: #
--echo # Disallowed casts to LINESTRING #
--echo ############################################
--echo #
--echo # Casting from POINT to LINESTRING is not allowed.
--echo # Must raise error.
--error ER_INVALID_CAST_TO_GEOMETRY
DO ST_ASTEXT(CAST(ST_GEOMFROMTEXT('POINT(1 1)') AS LINESTRING));
--echo #
--echo # Casting from MULTIPOLYGON to LINESTRING is not allowed.
--echo # Must raise error.
--error ER_INVALID_CAST_TO_GEOMETRY
DO ST_ASTEXT(CAST(ST_GEOMFROMTEXT('MULTIPOLYGON(((1 1, 2 2, 3 3, 1 1)))') AS LINESTRING));
--echo #
--echo #############################################
--echo # Testing result of WKT input #
--echo #############################################
--echo #
--echo # Casting from ST_GEOMFROMTEXT(<wkt>) to LINESTRING must return expected linestring.
SELECT ST_ASTEXT(CAST(ST_GEOMFROMTEXT('LINESTRING(1 1, 2 2)') AS LINESTRING));
SELECT ST_ASTEXT(CAST(ST_GEOMFROMTEXT('POLYGON((3 3, 4 3, 4 4, 3 4, 3 3))') AS LINESTRING));
SELECT ST_ASTEXT(CAST(ST_GEOMFROMTEXT('MULTIPOINT((5 5), (6 6))') AS LINESTRING));
SELECT ST_ASTEXT(CAST(ST_GEOMFROMTEXT('MULTILINESTRING((7 7, 8 8))') AS LINESTRING));
SELECT ST_ASTEXT(CAST(ST_GEOMFROMTEXT('GEOMETRYCOLLECTION(LINESTRING(9 9, 10 10))') AS LINESTRING));
--echo #
--echo #############################################
--echo # Testing result of user variable input #
--echo #############################################
--echo #
SET @linestring = ST_GEOMFROMTEXT('LINESTRING(1 1, 2 2)');
SET @polygon = ST_GEOMFROMTEXT('POLYGON((3 3, 4 3, 4 4, 3 4, 3 3))');
SET @multipoint = ST_GEOMFROMTEXT('MULTIPOINT((5 5), (6 6))');
SET @multilinestring = ST_GEOMFROMTEXT('MULTILINESTRING((7 7, 8 8))');
SET @geomcollection = ST_GEOMFROMTEXT('GEOMETRYCOLLECTION(LINESTRING(9 9, 10 10))');
--echo #
--echo # Casting from geometry in user variable to LINESTRING must return expected linestring.
SELECT ST_ASTEXT(CAST(@linestring AS LINESTRING));
SELECT ST_ASTEXT(CAST(@multipoint AS LINESTRING));
SELECT ST_ASTEXT(CAST(@multilinestring AS LINESTRING));
SELECT ST_ASTEXT(CAST(@geomcollection AS LINESTRING));
--echo #
--echo #############################################
--echo # Testing result of table column input #
--echo #############################################
--echo #
CREATE TABLE gis_linestring_castable (fid INTEGER NOT NULL PRIMARY KEY, g GEOMETRY);
INSERT INTO gis_linestring_castable VALUES
(101, ST_GEOMFROMTEXT('LINESTRING(1 1, 2 2)')),
(102, ST_GEOMFROMTEXT('POLYGON((3 3, 4 3, 4 4, 3 4, 3 3))')),
(103, ST_GEOMFROMTEXT('MULTIPOINT((5 5), (6 6))')),
(104, ST_GEOMFROMTEXT('MULTILINESTRING((7 7, 8 8))')),
(105, ST_GEOMFROMTEXT('GEOMETRYCOLLECTION(LINESTRING(9 9, 10 10))'));
--echo #
--echo # Casting from geometry column to LINESTRING must return expected linestring.
SELECT ST_ASTEXT(CAST(g AS LINESTRING)) FROM gis_linestring_castable;
--echo #
--echo # Cleanup.
DROP TABLE gis_linestring_castable;
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