ErlyDB now has many-to-many relations support

Rudolph van Graan <>
Thu Aug 31 08:16:55 CEST 2006


Hey Yariv,

I think you are certainly onto something here... A couple of comments  
below.

Looking over the code for project, developer etc the one thing that  
bugs me is that I cannot see which fields/methods the files contain.  
So it is cool being able to generate the methods on the fly, but it  
makes very little sense not being able to guarantee what methods will  
be in the module between regeneration attempts. I am tempted to say  
that you will have to build in some mechanism with which to  
explicitly define methods. Maybe generate a .hrl file or a .erl that  
is a stub calling the dynamic code. Look at the orber mechanism for  
translating IDL files in erlang - that creates explicit function  
definitions.

So looking at this:

-module(project).
-compile(export_all).

relations() ->
     [{many_to_one, [language]},
      {many_to_many, [developer]}].

I cannot see the table name it maps to (assuming it is the same as  
the module name?), nor that it is actually a dynamically generated  
module (think -behaviour(....) ) or maybe use a couple of attribute  
flags in the code. Also, I cannot see from the relations() which  
fields link to which in the tables - it is not necessarily true that  
the fields have the same name in both tables or do you reverse  
engineer the relations on the database level to establish these links?

Rgds,

Rudolph van Graan

Pattern Matched Technologies
Web:     www.patternmatched.com


On 31 Aug 2006, at 4:00 AM, Yariv Sadan wrote:

> Hi,
>
> I added features to make dealing with many-to-many relations with
> ErlyDB a breeze.
>
> I also made many-to-one SELECT queries more powerful.
>
> Here's the announcement with a tutorial
>
> http://yarivsblog.com/articles/2006/08/30/many-to-many-relations- 
> are-now-at-an-erlydb-near-you
>
> Enjoy!
>
> Best,
> Yariv
>




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