[Erw-devel] Trying to understand how to incorporate relations into filters

[erw-devel]

I have a table from a non-profit I'm working with that looks like this:

FirstName LastName Question1 Question2 Question3 Question4 (ad nauseum)


They are only interested in the 'Yes' responses so I had the idea of storing it 
as follows:

yes.xml:

<?xml version="1.0"?>

<!DOCTYPE erl PUBLIC "-//DSI//DTD ERL V1.2//EN" "file://erl.dtd">

<erl id="yes" title="Yes - a relation test">

<ent id="members" label="MEMBERS" owner="true">
        <attr id="FirstName" label="First Name" type="varchar" mand="false"/>
        <attr id="LastName" label="Last Name" type="varchar" mand="false"/>
</ent>

<ent id="questions">
        <attr id="question"/>
</ent>

<rel id="responses" label="Answers to questions">
        <leg entref="members" upper="N" label="Said Yes to ..."/>
        <leg entref="questions" upper="N" label="member"/>
</rel>
</erl>

I was attempting to use the existence of the relation as a filter. By looking 
in the defs
file that gets generated I see a reference to 'responses_questions' that gets 
created. I
thought perhaps this might do something (after not quite getting the 
documentation on the
subject):

custom/members.php:

<?php
$D["members"]["display"]["fmtString"] = " %s, %s";
$D["members"]["display"]["field"] = array( "LastName", "FirstName" );

$D["members"]["filter"] = array();
$D["members"]["filter"]["LastName"]["type"] = t;
$D["members"]["filter"]["LastName"]["operator"] = "=";
$D["members"]["filter"]["LastName"]["label"] = "Last Name";

$D["members"]["filter"]["responses_questions"]["type"] = rN;
$D["members"]["filter"]["responses_questions"]["label"] = "Responses to 
Questions";

?>

This does put 'Responses to questions' in the filter area, with the ability to 
select
questions that are in the d/b, but it doesn't filter them. I saw a reference to 
a 
'trick' with IDs and nulls that seemed like it might apply, but I'm a bit lost 
where
to try next. I'm certain the 'responses_questions' is not right, it should be 
something
more like responses_0->questions_1.question or some such thing.

Should this work? Any suggestions how to grok the syntax? Do i look at the 
table definitions
or the defs files to get the names to build up the path to the right level?

Thanks,
Alfred Werner


P.S.  - table schemas here:
mysql> show tables;
+---------------+
| Tables_in_yes |
+---------------+
| members       |
| questions     |
| responses     |
+---------------+
3 rows in set (0.00 sec)

mysql> desc members;
+--------------+--------------+------+-----+---------+-------+
| Field        | Type         | Null | Key | Default | Extra |
+--------------+--------------+------+-----+---------+-------+
| id           | int(11)      |      | PRI | 0       |       |
| id_owner_usr | int(11)      | YES  |     | NULL    |       |
| id_share_grp | int(11)      | YES  |     | NULL    |       |
| FirstName    | varchar(255) | YES  |     | NULL    |       |
| LastName     | varchar(255) | YES  |     | NULL    |       |
+--------------+--------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

mysql> desc questions;
+----------+--------------+------+-----+---------+-------+
| Field    | Type         | Null | Key | Default | Extra |
+----------+--------------+------+-----+---------+-------+
| id       | int(11)      |      | PRI | 0       |       |
| question | varchar(255) | YES  |     | NULL    |       |
+----------+--------------+------+-----+---------+-------+
2 rows in set (0.00 sec)

mysql> desc responses;
+---------------+---------+------+-----+---------+-------+
| Field         | Type    | Null | Key | Default | Extra |
+---------------+---------+------+-----+---------+-------+
| id            | int(11) |      | PRI | 0       |       |
| id0_members   | int(11) |      | MUL | 0       |       |
| id1_questions | int(11) |      |     | 0       |       |
+---------------+---------+------+-----+---------+-------+