How to convert/typecast from Polygon to Multipolygon in PostGIS?

Question

Is there any way to typecast Polygons to Multipolygon type?

For example, I have created a circle using ST_Buffer() on a point. The return type of that function is of Polygon type. The problem is that on the geometry column there is a restriction limiting it to Multipolygon type. So, I cannot insert a simple polygon.

I have used ST_MPolyFromText() function, but as usual it is returning null for that and ST_Dump() is not giving the proper output.

The constraint is:

CONSTRAINT enforce_geotype_geom CHECK (geometrytype(geom) = 'MULTIPOLYGON'::text OR geom IS NULL),

Answer 1

ST_Multi - Returns the geometry as a MULTI* geometry. If the geometry is already a MULTI*, it is returned unchanged.

Example:

SELECT ST_AsText(ST_Multi(ST_GeomFromText('POLYGON((743238 2967416,743238 2967450,
        743265 2967450,743265.625 2967416,743238 2967416))')));
        st_astext
        --------------------------------------------------------------------------------------------------
        MULTIPOLYGON(((743238 2967416,743238 2967450,743265 2967450,743265.625 2967416,
        743238 2967416)))
        (1 row)