Let say, we have a event management product for an user. One feature is, user could self-define new field to accommodate his own need, for example, he could add "do I take morning exercise today? Yes Or No " checkbox to the system, afer this, the new field will show up on the screen and its column is added to database without restart
How to design this system ? what technology is good ?
Usually we will define POJO class and mapped to database and show them on the screen. Here problem, if user dynamically add a new filed, we can't modify POJO in the runtime.
This is a challenge.
Thanks.
Hong Anderson
Ranch Hand
Joined: Jul 05, 2005
Posts: 1936
posted
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You can use JDBC, and keep schema in XML.
For dynamic schema, you cannot use "hard-coded" classes, you need to have generic ones, like EntityData, EntityType.
Try to think about what methods EntityData and EntityType should have.
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I can define object properties in xml, user could add / delete property from xml file. Then I write a JDBC generator converting xml to JDBC. This should be work.
Then another problem arises. how to define it in JSP page ? what is sequence ? do I need to define a sequence number in XML file ? or we have another options ?
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