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I have an existing entity design. There is an Individual entity. A Guardian or a Minor are stored as Individual. If u r a Minor, u r assigned zero or more guardians. This relationship is stored in a different entity.

There is an additional requirement; to add a flag to show that Guardian Address should be used for the Minor if the relationship is set. One can clear that flag at a later time. If the flag is cleared, the existing address will be used and no changes to guardian's address will overwrite the minor's address.

The relationship between Minor and Guardian is stored as

(minor_individual_id, guardian_individual_id, type_of_the_relationship)

where type_of_the_relationship can have values such "legal" etc..

Is it as simple as adding a new flag to the relationship table ? Once added, the minor's address needs to be changed to the guardian's address. The address information is stored in another entity (Address). Can this be done via Hibernate built-in functionality ? Or should we add a layer to take care of this functionality ? Is there anything in Hibernate that lets me know the flag has been updated and a new set of updates need to happen ?

The address entity contains the individual id and the address for the individual in a single table.

Once the flag is set, it can only be set once per minor since it will cause confusion to have minor having multiple guardians to have address cascade to be turned on for each of its guardians. Thanks.

Database Structure:
Individual ( Table/Entity)
Id
Age ( Depending on Age, you are treated as minor )

GuardianRelationShip ( Table/Entity)
Minor_Individual_Id
Guardian_Individual_Id

Address (Table/Entity)
Individual_Id
AddressLine1
City
State

If u r a Minor with Individual id of 2 and a have a Guardian with Individual id of 1. This will look like

Id Age (Individual)
1   40 Guardian
2    5 Minor

Minor Guardian (GuardianRelationShip)
2     1

IndividualId City State (Address)
1            LA    CA
2            NY    NY

Once those are linked, the idea is that the address for the minor "individual id of 2" will be changed to NY/NY.

If there is a req. that says use guardian address for minor and allow for unlinking address, how would you do that ?

frictionlesspulley
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Ender Wiggin
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2 Answers2

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You have the AddressEntity. I would create IndividualEntity.address and minor's address could reference the same AddressEntity as one of guardians (BTW, several guardians could live at the same address too!). Afterwards, you could check if minor's address equals to one of guardian's address.

I don't understand which problem the flag solves. Please provide more info, along with some code to illustrate your entities and relations.

kan
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  • Correct, but in your ideal world. Address is stored as address and a reference to the address is stored in another entity. In this world both are merged so if two people live in the same address, there are two rows of data with the difference being the individual id. Hence for me to change the address of the minor, I have to physically overwrite the minor's address. – Ender Wiggin Oct 11 '11 at 16:30
  • So, you have fk in address to reference an individual? Not vice versa? In this case you could make a reference from MinorEntity to the address anyway. (Or not to address, but to the RelationshipEntry, to guarantee that a minor references its guardian's address) – kan Oct 11 '11 at 16:36
  • Minor and guardians are not entities. They are just user's definition of relationship between two individuals. I will try to update the edit better to show the existing erd. – Ender Wiggin Oct 11 '11 at 17:58
  • Anyway, you have to change the database structure. What kind of limitations do you have of changing data model? Could you change it properly? – kan Oct 12 '11 at 09:24
  • Problem is changing data model. Upper management is fearful of changing data model and cause issues so it has to work with the coexisting design. – Ender Wiggin Oct 12 '11 at 19:41
  • The existing design doesn't allow implement the requirements. Anyway you have to introduce some changes. However, you could discuss it with a DBA, in most cases it's possible to maintain changes properly, keeping compatibility by creating views, aliases, etc. – kan Oct 12 '11 at 19:51
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Allow an Individual entry without a corresponding Address entry. If you want to limit it to just guardians, only permit that case when the entry for the Individual table doesn't have a corresponding match in the GuardianRelationship.Minor column. If address is null, lookup guardian and use that address.

If you do enforce that rule above, make sure you consider edge cases that change the structure such as an individual no longer having a listed guardian and having no address.

Jeff Ferland
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  • That will not work since the req. states that the guardian address should be used but the user can override. That definitely requires for me to store the user decision. – Ender Wiggin Oct 11 '11 at 21:46
  • @EnderWiggin Inserting an address for the minor is an override. If it's null, the parent's address. If another address, an override. – Jeff Ferland Oct 11 '11 at 22:13
  • I see but couple issues; if you donot find an address you assume that the address is linked. That means they can try to enter an address for the minor which will break the link. How do you solve the corner case, you mention ? Also how do you know which guardian's address to use ? – Ender Wiggin Oct 11 '11 at 22:28
  • Some high-level logic to copy the address over on delete would work. If you have a case with two guardians, you may then wish for a household / address table and an associated individual-to-address table. That does remove the null consideration I had above. – Jeff Ferland Oct 12 '11 at 00:53