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Mapping Suggestion needed

I have a table which contains 3 columns id,key,value. The data in the table looks like this :-

1)1,userId,test
2)1,firstName,foo
3)1, lastName, foo Test

Now when i query the table  :-

List<Property> values = hibernateDao.findById("xx");

I get list of values as i mentioned above. I can do this :-

User user = new User();
foreach(Property prop : values ) {
if(prop.getKey().equalsIgnoreCase("userId") {
user.setUserId(prop.getValue()):
}
if(prop.getKey().equalsIgnoreCase("firstName") {
user.setFirstName(prop.getValue());
}
.
.
}
return user;

This works fine but i am trying to find more efficient way of doing it instead of using nested if statements.
0
Micheal_Male
Asked:
Micheal_Male
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1 Solution
 
for_yanCommented:
And what is Property ?
Is it a type defined by Hibernate ?
0
 
Micheal_MaleAuthor Commented:
Its an entity class
0
 
for_yanCommented:
But who defines it? Does it implement Comparable?
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Micheal_MaleAuthor Commented:
It's just a class itself which holds field names id,key and value. It does not implement comparable.
0
 
Micheal_MaleAuthor Commented:

@Entity
@Table(name="property")
public class Property {

@OneToMany(mappedBy="property")
@JoinColumn("id")
private String id;
@Column(name="key")
private String key;
@Column(name="value")
private String value;

Open in new window

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for_yanCommented:

If you defined it in your code, then you can implement Comparable
and define compareTo method
in such a way that Collections.sort(values) will produce the known order of keys,
then you would not need to check with if's but could know that fiirst element corresponds
say to userid, second to first name, etc

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Micheal_MaleAuthor Commented:
hmm that sounds a little dangerous if someone else adds a new key or it might break by putting the wrong key value in user pojo.
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for_yanCommented:
That is true.
If I were you, I would go for if's, as you mentioned in your original post; don't see any problems with those.
I just suggested, as you were looking for possible alternatives.  
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josephtsangCommented:
what about refactoring your code with the Visitor design pattern?
0
 
josephtsangCommented:
Work in this way:

1. Replace all lines inside the for-loop by these 2 lines


Setter<User> setter = setterMap.get(prop.getKey());
setter.set(user, prop.getValue())

Open in new window


2. Before entering the for-loop, prepare a setter map as follows


Map<String,Setter<User>> setterMap = new HashMap<String,Setter<User>>();
setterMap.put( "userId", new Setter<User> { 
	public void set(User user, String value) { user.setUserId(value); } });
setterMap.put( "firstName", new Setter<User> { 
	public void set(User user, String value) { user.setFirstName(value); } });
setterMap.put( "lastName", new Setter<User> { 
	public void set(User user, String value) { user.setLastId(value); } });

Open in new window


3. Define a private inner interface Setter in your class


private interface Setter<T> { 
	public void set(T t, String value); 
}

Open in new window


So if you have defined any new key-value pairs for the records, you just need to put a new entry into the map in Step 2. Others just keep the same. Less code change for the enhancement.
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Micheal_MaleAuthor Commented:
Great. However I just found a mapping framework also. Hopefully that will suffix my needs.
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