Large object sample script is out of date about ruby-pg HOT 6 CLOSED

Original comment by Michael Granger (Bitbucket: ged, GitHub: ged).

Please use the 'pg' library instead of the 'postgres' one. The 'postgres' library has numerous known problems, not the least of which is its implementation of large objects.

If you're looking at 'pg.c' (which is the extension source for 'pg', not 'postgres'), you'll notice that the documentation for both [[http://bitbucket.org/ged/ruby-pg/src/tip/ext/pg.c#cl-2689|lo_creat]] and [[http://bitbucket.org/ged/ruby-pg/src/tip/ext/pg.c#cl-2716|lo_create]] document that it returns a Fixnum, which is the Oid of the created object.

You are correct about sample/losample.rb, though. Most the files in that directory are horribly out of date. I'll fix the losample ASAP to reflect pg's interface.

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Original comment by fredericp (Bitbucket: fredericp, GitHub: fredericp).

Sorry, wasn't clear enough in my first report. I am using the 'pg' library, and I know that these functions do return a FIXNUM from looking at the source-code. But IMHO that isn't documentation, http://bitbucket.org/ged/ruby-pg/src/tip/doc/postgres.html is. And the information in that file is clearly not up to date.

Which calling-sequence do I have to use to create and open a large object so that I can write to it? The appended example-script doesn't work.

#!ruby

farnsworth: ~/ruby$ cat -n pgtest.rb 
     1	require 'rubygems'
     2	require 'pg'
     3	
     4	mydata = 'this is my special test string'
     5	db = PGconn.open(:host => 'myhost', :user => 'myuser', :password => 'mypassword', :dbname => 'mydb', :sslmode => 'require')
     6	
     7	oid = db.locreat(PGconn::INV_READ | PGconn::INV_WRITE)
     8	lo = db.loopen(oid, PGconn::INV_READ | PGconn::INV_WRITE)
     9	lo.write(mydata)
    10	lo.close
    11	db.close

farnsworth: ~/ruby$ ruby pgtest.rb 
pgtest.rb:9: undefined method `write' for 0:Fixnum (NoMethodError)

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Original comment by Michael Granger (Bitbucket: ged, GitHub: ged).

Modified the large-object sample script to reflect the pg library's API (refs #35)

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Original comment by Michael Granger (Bitbucket: ged, GitHub: ged).

The 'postgres.html' file is documentation for the 'postgres' library, which is why I assumed you were using it. I will be removing it shortly, as it has been replaced by inline documentation which can be extracted using RDoc. I'll also post a link to the generated docs on my server so you don't need to generate them yourself.

I've replaced the large-object sample script with one that works for the 'pg' library; I'd be happy to answer questions about it.

You example code should look something like:

#!ruby

require 'rubygems'
require 'pg'

mydata = 'this is my special test string'
db = PGconn.open(:host => 'myhost', :user => 'myuser', 
	:password => 'mypassword', :dbname => 'mydb', 
	:sslmode => 'require')

db.exec("BEGIN")
oid = db.locreat(PGconn::INV_READ | PGconn::INV_WRITE)
lo = db.loopen(oid, PGconn::INV_READ | PGconn::INV_WRITE)
db.lowrite(lo, mydata)
db.loclose(lo)
db.exec("COMMIT")
db.close

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Original comment by fredericp (Bitbucket: fredericp, GitHub: fredericp).

Thanks a lot, that did the trick :-)

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Original comment by Michael Granger (Bitbucket: ged, GitHub: ged).

Happy to help. Thanks for helping to improve the documentation! :)

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