in reply to Re: Class::DBI has_a relationships
in thread Class::DBI has_a relationships

Hi, thanks for the help. Can you explain what
__PACKAGE__->has_many(
   sessions => [EP::Common::DBI::Sessions_Metadata => 'id'] 
            => 'session_id'
);

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is doing?

According to the Class::DBI perldoc, has_many works like:
has_many(method_to_create=>"foreign_class");
so I thought I needed something like: __PACKAGE__->has_many(sessions_metadata=>"EP::Common::DB::Sessions::Metadata");
in both Users and Sessions to declare that Sessions_Metadata was referencing them. But I get the same 'can't bind a ref error'.

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3Re: Class::DBI has_a relationships
by jeffa (Bishop) on May 18, 2004 at 17:07 UTC

    That (what you have) declares that a User has many Sessions::Metadata and that a Session has many Sessions::Metadata, but you also have to tell Sessions::Metadata that it references Users and Sessions as well.

    My snippet in question is specifying that a User can have many Sessions::Metadata classes, and the Users' foreign key 'session_id' references the Sessions::Metadata primary key 'id'. Now, whether or not this is the right fit for your database table relationship is the question, and since i don't know what it looks like, i can only speculate.

    jeffa

    L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)
[reply]
      OK. descriptions of tables are below.

      Both Users and Sessions are referenced by Sessions_Metadata

      Class::DBI doc says has_many is used to declare that another table is referencing us, so both Users and Sessions need a has_many(sessions_metadata)?

      I tried this in sessions: 

      __PACKAGE__->has_many(
                      sessions_metadata=>['EP::Common::DBI::Sessions_M
+etadata' => 'session_id' ]
                      => 'id'
);

      [download]
      (and equiv in users) which I was hoping meant that 'session_id' is an FK in Sessions_Metadata which refers to 'id': the PK in sessions.
      Still get the same error.
      have I got the wrong end of the stick? 
      sessions_metadata
   Column    |          Type          | Modifiers 
-------------+------------------------+-----------
 session_id  | character(32)          | not null
 username    | character varying(40)  | 
 create_date | character varying(100) | 
 expire      | character varying(100) | 
 query_id    | character varying(50)  | 
Indexes: sessions_metadata_pkey primary key btree (session_id)
Foreign Key constraints: $1 FOREIGN KEY (session_id) REFERENCES sessio
+ns(id) ON UPDATE NO ACTION ON DELETE NO ACTION,
                         $2 FOREIGN KEY (username) REFERENCES users(us
+ername) ON UPDATE NO ACTION ON DELETE NO ACTION

sessions

  Column   |     Type      | Modifiers 
-----------+---------------+-----------
 id        | character(32) | not null
 a_session | text          | 
Indexes: sessions_pkey primary key btree (id)

users

    Column    |          Type          |     Modifiers      
--------------+------------------------+--------------------
 username     | character varying(40)  | not null
 password     | character varying(40)  | not null
 salt         | smallint               | not null
 session_only | smallint               | not null default 0
 first_name   | character varying(40)  | not null
 last_name    | character varying(40)  | not null
 institute    | character varying(255) | 
 department   | character varying(255) | 
 address      | character varying(255) | 
 telephone    | character varying(255) | 
 email        | character varying(100) | not null
Indexes: users_pkey primary key btree (username)

      [download]
[reply]
[d/l]
[select]

        Seems to me that your relationships are a bit off. At first i thought that Sessions_Metadata was a cross reference between Users and Sessions. But it is not. Instead, it is extra info for a session. Now, if this were my project, i would only have two tables: Users and Sessions. It seems to me that everything in Sessions_Meta data relates to a session, therefore, why not just put those attributes in the Sessions table? 

        sessions
   Column    |          Type          | Modifiers 
-------------+------------------------+-----------
 id          | character(32)          | not null
 a_session   | text                   | 
 username    | character varying(40)  | 
 create_date | character varying(100) | 
 expire      | character varying(100) | 
 query_id    | character varying(50)  |
        It will greatly simply your task. Also ... why are you using a character type for the primary key? You should be using an "auto-incremented" integer, preferably unsigned. Likewise, you should also be using the same for your primary key in the Users table.

        UPDATE:
        I think that is correct, CassJ.

        jeffa

        L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)
[reply]

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