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OO, Patterns, UML and Refactoring
I need Design advice...
Joined: Sep 18, 2005
Jun 18, 2006 21:18:00
Hi, I'm implementing a search module for my app. I was thinking if there is a good technique I could use for this.
if the user entered no search options( there are 3 options required like age preference, religion and citizenship). I was thinking of an implementation like this but it doesn't look elegant...
if (preferredAge.equals("") || religion.equals("") || citizenship.equals("") )
dao.search(preferredAge, religion, citizenship)
that's making an overloaded version of search method. Any better ideas? Thanks!
Joined: May 24, 2005
Jun 18, 2006 21:38:00
How about you encapsulate this into dao.search(age, religion, citizen).
If this is sql query:
query = "select * from user_table where <default_conditions> " +
age.equals("")? "" : "age = ? " +
religion.equals("")? "" : "religion = ? " +
citizen.equals("")? "" : "citizen = ? " ;
By no means this is complete code, but should give you the idea.
Joined: Jan 29, 2003
Jun 19, 2006 10:43:00
Years ago I had a complex search screen in an environment that did not allow dynamic SQL. I made a "bitmap" of which fields were entered by the user:
if first-name is not null, set bit 1
if last-name is not null, set bit 2
if city is not null, set bit 4
if state is not null, set bit 8
and then made a mapping of bitmap values to prepared sql statements
if bitmap = 1 query first name only else if bitmap = 3 query first name and last name else invalid combination of fields!
I might resort to the same trick if the combinations of fields were really tricky.
But it's simpler to
for a few valid ones. Today we do dynamic SQL and test for minimum required inputs:
if ( firstname and lastname ) ok else if ( lastname and state ) ok else throw "specify more search criteria!" build dynamic sql with whatever we got
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi
I agree. Here's the link:
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