[postgis-users] RC6 + ArcObjects
Craig Miller
craig.miller at spatialminds.com
Tue Apr 12 15:59:30 PDT 2005
I believe lightweight geometry (LWGEOM) stored in the database whereas the
asBinary() function returns OGIS WKB.
--Craig
-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Abe
Gillespie
Sent: Tuesday, April 12, 2005 3:50 PM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] RC6 + ArcObjects
Ok, I've now reproduced the problem with ODBC. The data that comes
from the server as a byte array - in code - is different from what's
actually in the database. I compare values by looking at the hex
representation in the debugger and the values in pgAdmin Query (and
also the sql script generated by shp2pgsql to double-check).
I believe this sufficiently removes the possibility of the problem
being in Npgsql or ArcObjects. So I gather it's either in
PostgreSQL's ability to xmit the correct data or a problem with the
asbinary() func.
I'm running RC6 with the latest Windows install of Postgres. I tested
against my Linux install and was having problems there too. But
Postgres and PostGIS are rather old on my Linux box anyhow.
I'm not sure where to go from here. Please let me know if I can help.
-Abe
On Apr 12, 2005 5:39 PM, Abe Gillespie <abe.gillespie at gmail.com> wrote:
> Ok, I've confirmed that the data I get into a byte array is different
> than what should be in the actual database. I'll try to see if it's a
> problem with the Npgsql data provider by testing against the
> PostgreSQL ODBC driver. I'll check back when I've tested.
>
> -Abe
>
> On Apr 12, 2005 4:18 PM, strk at refractions.net <strk at refractions.net>
wrote:
> > On Tue, Apr 12, 2005 at 03:43:20PM -0400, Abe Gillespie wrote:
> > > Well, I did do a few small by-hand tests going from WKB to ArcObjects
> > > and vice versa (in fact, some where examples from MySQL ... heh).
> > > Those all worked ok. Maybe I just havn't come up with the right
> > > example yet. The weird thing though, is a given record will work
> > > sometimes but other times not. That's where I'm confused.
> >
> > If you can get postgis return different results with the
> > same query on the same record that would be a good bug report!
> >
> > --strk;
> >
> > >
> > > Anyone know where I can get my hands on the WKB spec?
> > >
> > > Thanks for the help.
> > > -Abe
> > >
> > > On Apr 12, 2005 3:26 PM, Darren Houston <dhouston at beyondcompliance.ca>
wrote:
> > > > Hello Abe,
> > > >
> > > > I didn't spend much time on the following situation so I don't know
how
> > > > correct this statement is.
> > > >
> > > > I have a friend who is playing around with MySQL WKB and ArcObjects.
He is
> > > > having similar problems as you. Looking deeper, he found that the
WKB
> > > > ArcObjects produced is not the same as WKB from MySQL and therefore
probably
> > > > PostGIS. I looked at the WKB that he sent me for the same point from
> > > > ArcObjects and MySQL - MySQL looked correct but ArcObjects WKB
looked wrong
> > > > (it started off with what looked like default bits for padding or
something
> > > > else specific to ArcObjects). I would honestly look at the WKB
objects from
> > > > ArcObjects as the problem, comparing input and output. Like I said,
I looked
> > > > at both WKB outputs and told my friend "MySQL is right, ArcObjects
is wrong".
> > > > That is as far as I took it. But nonetheless, I hope this helps you
some.
> > > >
> > > > Darren H.
> > > >
> > > > On April 12, 2005 11:51 am, Abe Gillespie wrote:
> > > > > The SQL query always succeeds. It's when the WKB data is
converted to
> > > > > an ArcObject via geoEnv.CreateGeometryFromWkbVariant(bin, out geo,
out
> > > > > byteCnt) do I encounter intermittent problems. I realize this
could
> > > > > be a problem with the CreateGeometryFromWkbVariant call, but could
it
> > > > > be data from PostGIS causing the problem? I'm not sure how to
verify
> > > > > this.
> > > > >
> > > > > -Abe
> > > > >
> > > > > On Apr 12, 2005 1:43 PM, strk at refractions.net
<strk at refractions.net> wrote:
> > > > > > Abe, if you want to find out you should try to provide
> > > > > > a simple SQL-only script showing the problem.
> > > > > > --strk;
> > > > > >
> > > > > > On Tue, Apr 12, 2005 at 12:06:05PM -0400, Abe Gillespie wrote:
> > > > > > > I'm dabbling in connecting / using PostGIS in ESRI ArcObjects.
I'm
> > > > > > > experiencing intermittent problems though. I've included the
code I'm
> > > > > > > using below. I realize there are three different technologies
> > > > > > > entering the mix here: Npgsql, PostGIS, and ArcObjects.
However, I'm
> > > > > > > led to believe the problem is with PostGIS and not the others;
this
> > > > > > > use to fail *every* time in earlier PostGIS releases.
> > > > > > >
> > > > > > > The thing to notice is different runs produce different
outputs. The
> > > > > > > output being the IDs of the records throwing exceptions.
> > > > > > >
> > > > > > > I've attached the sql script of the problematic data. I'd
appreciate
> > > > > > > it if anyone could look into this but also realize this
problems spans
> > > > > > > multiple areas of expertise.
> > > > > > >
> > > > > > > Thansk.
> > > > > > > -Abe
> > > > > > >
> > > > > > > // begin code -->
> > > > > > > using System;
> > > > > > > using ESRI.ArcObjects.Core;
> > > > > > > using Npgsql;
> > > > > > >
> > > > > > > namespace WKB
> > > > > > > {
> > > > > > > class Program
> > > > > > > {
> > > > > > > static void Main(string[] args)
> > > > > > > {
> > > > > > > // Connect to PostGIS and query.
> > > > > > > NpgsqlConnection con = new
> > > > > > > NpgsqlConnection(connectionString); con.Open();
> > > > > > > NpgsqlCommand cmd = con.CreateCommand();
> > > > > > > cmd.CommandText = "select asbinary(the_geom) as
shape,gid
> > > > > > > from roads;";
> > > > > > > NpgsqlDataReader dr = cmd.ExecuteReader();
> > > > > > >
> > > > > > > // Setup objects and ArcObjects.
> > > > > > > object bin;
> > > > > > > IGeometry geo;
> > > > > > > int byteCnt;
> > > > > > > GeometryEnvironmentClass geoEnv = new
> > > > > > > GeometryEnvironmentClass();
> > > > > > >
> > > > > > > while (dr.Read())
> > > > > > > {
> > > > > > > bin = null;
> > > > > > > geo = null;
> > > > > > > byteCnt = 0;
> > > > > > >
> > > > > > > bin = dr["shape"];
> > > > > > > try
> > > > > > > {
> > > > > > > // Try to convert raw data into an
ArcObject.
> > > > > > > geoEnv.CreateGeometryFromWkbVariant(bin,
out geo,
> > > > > > > out byteCnt);
> > > > > > > }
> > > > > > > catch
> > > > > > > {
> > > > > > > // There was a failure.
> > > > > > > // The exception always has a generic
description.
> > > > > > > Console.WriteLine(dr["gid"].ToString());
> > > > > > > continue;
> > > > > > > }
> > > > > > > }
> > > > > > > }
> > > > > > >
> > > > > > > static private string connectionString { get { return
> > > > > > > "your_con_str_here"; } }
> > > > > > > }
> > > > > > > }
> > > > > > > // <-- end code.
> > > > > > >
> > > > > > > _______________________________________________
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