I'm currently having problems getting getting parent/child relationships working in Class::DBI in order to represent a directed graph structure.

I have two database tables, one of Nodes (With an integer acting as a primary key), and a relationships table with parent and child fields which refer to the primary key of the nodes table.

What I really want is to be able to do @children = $node->children() and @parents = $node->parents(). With the structure being what it is any node can have multiple parents and multiple children so having a single parent field in the Node table would not work.

I've tried to get this working with both Class::DBI alone, and with Class::DBI::Join, but just don't seem able to get it to work whatever I try. Join doesn't seem to like the fact the relationship has a compound primary key, and that both of it's fields refer to objects of the same type.

Is there any nice and tidy solution, or shall I just code the SQL into the classes by hand?

In reply to Hierarchial relationships in Class::DBI by Molt

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.