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Hi everyone, Ok, seems to be a big weekend for new features. Here’s
one some of you might find useful: multi-step linking relationships. With older versions of reactor you could establish relationships
between two separate objects via linking relationships. IE: If you have three
tables, user, userAddress, address. A userAddress hasOne of both User and
Address and User and Address have many of each other this is what your xml
would look like: <object name="User"> <hasMany
name="Address"> <link
name="UserAddress" /> </hasMany> </object> <object name="UserAddress"> <hasOne
name="User"> <relate
from="userId" to="userId" /> </hasOne> <hasOne
name="Address"> <relate
from="userId" to="userId" /> </hasOne> </object> <object name="Address"> <hasMany
name="User"> <link
name="UserAddress" /> </hasMany> </object> This would allow you to get an Iterator of all Addresses for
a user and an Iterator of all Users for an address. However, let’s
say that you have an additional table, State. And let’s say you
want to get an Iterator of all states your users are in. Previously you’d
have to create your own custom method. Now, you could update your xml to
look like this: <object name="User"> <hasMany
name="Address"> <link
name="UserAddress" /> </hasMany> <hasMany
name="State"> <link
name="UserAddress" /> <link
name="Address" /> </hasMany> </object> <object name="UserAddress"> <hasOne
name="User"> <relate
from="userId" to="userId" /> </hasOne> <hasOne
name="Address"> <relate
from="userId" to="userId" /> </hasOne> </object> <object name="Address"> <hasMany
name="User"> <link
name="UserAddress" /> </hasMany> <hasOne
name="State"> <relate
from="stateId" to="stateId" /> </hasOne> </object> <object name="State" /> Now, from your UserRecord you could call getStateIterator()
and you would end up with a query of all the states your users are in. This
will not automatically add a distinct so you’ll want to update your Iterator
to only return distinct rows in this case. This works by automatically creating a join from User to
UserAddress to Address to State and only returning rows from State. Also, linking relationships don’t care what type of
relationship they link through. You can link through hasOne or
hasMany. Furthermore, only one relationship needs to be defined between two
objects. From the previous example, the Address is configured to have one
state, but a state isn’t configured to have any addresses. This
gives you a lot of power to establish relationships however you need. So, give it a try again and let me know if you have any
problems. Doug |
