[postgis-users] geometryfromtext problem

[Joel Gwynn]

Carl Anderson wrote:

> On 04/10/2004 10:42:17 AM, Joel Gwynn wrote:
>
>> I'm having trouble doing something I've done before.  I've got a  
>> geometry column, but for some reason I can't populate it.  I have a  
>> lat field and a long field (both floats) that i'm trying to use to  
>> populate the_geom like so:
>>
>> update locations set the_geom=GeometryFromText('POINT (' || 
>> cast(long  as varchar(10)) || ' ' || cast(lat as varchar(10)) || ')', 
>> -1);
>>
>> which yields:
>>
>> ERROR:  Function 'geometryfromtext(varchar, int4)' does not exist
>>        Unable to identify a function that satisfies the given  
>> argument types
>>        You may need to add explicit typecasts
>>
>
> update locations set the_geom=GeometryFromText(('POINT (' || cast(long
> as varchar(10)) || ' ' || cast(lat as varchar(10)) || ')')::geometry,
> -1);
>
> Pg will not always do an imlicit cast when you are || thing together
> and a explicit cast is necessary.
>
> looking at the definition of  (using \df geometryfromtext
> you'll see
>   GEOMETRYFROMTEXT (geometry, integer)
>
> so PostGIS is relying on the implicit cast from text -> to geometry
>
> CREATE CAST ( text AS geometry) WITH FUNCTION geometry(text) AS  
> IMPLICIT;
>
> your complex statement just confused the type casting mechinism in  
> Postgres.
>
> alternative forms of you statement
>
> update locations set the_geom=GeometryFromText(gometry('POINT (' ||  
> cast(long
> as varchar(10)) || ' ' || cast(lat as varchar(10)) || ')'),
> -1);
>
> update locations set the_geom=GeometryFromText(cast(('POINT (' || cast 
> (long  as varchar(10)) || ' ' || cast(lat as varchar(10)) || ')') as  
> geometry),  -1);
>
> note that i am grouping the || strings with ( ) so that Postgres does  
> not cast only the first or last member or the list
>
> 'POINT('||lat_str||' '||long_str||')'::geometry is not the same as
> ('POINT('||lat_str||' '||long_str||')')::gemetry
>
> C.
>
> Carl Anderson
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>

Thanks.  That did it.  I could have sworn I didn't have to do so much 
casting about last time.