> Hi.
>
> I am using boost multi-index container for storing objects of type class A, in the class key1 &

> Key 3 are unique and key2 is non-unique. I try to insert objects of type A and it works fine.

>  No issues.
>
> At some point after the insertion, I wish to modify the key2 to 20  in the container. Can I do this

> with modify? If yes How do I define the iterator (since I need to do a find based on key1 but

> modify key2 in the container)

 

You have two options:

 

1. Use modify(), which is passed the entire element rather than the key, and

modify key2 at your pleasure.

2. Project the key1-iterator to a key2-iterator using the projection facilities:

 

 

and then use modify_key() with the key2-iterator.

 

BTW, I've noticed that you're wrapping the A objects into a DataMap class

that, oddily enough, replicates the key1, key2 and key3 members. Why aren't

you using A members directly thus disposing of the DataMap wrapper?

 

Joaquín M López Muñoz

Telefónica, Investigación y Desarrollo