best way to use a Map?

[Rusty Wright <ru...@gmail.com>]

I'm trying to figure out how to set up storing a Map of pairs of 
numbers.  I have a Photo object, and it has a Map of the different sizes 
in which the Photo is stored on disk.  The map keys are SIZE1, SIZE2, 
and SIZE3 (an enum; the map is an EnumMap).  The values in the Map are a 
simple object, ImageSize, with width and height fields. Each photo has 
its own sizes; no relationships and the widths and heights are 
essentially random values.

I'm thinking that in my database, each row for a Photo will have columns 
size1_width, size1_height, size2_width, size2_height, etc.  Doesn't 
sound too elegant but I can't see any other way.

I can't see any way to get these widths and heights into and out of the 
database other than to have getters and setters for each one. In order 
to not clutter my Photo class with those getters and setters I was 
thinking of making a PhotoDto data transfer object that does have the 
getters and setters and to wrap a Photo object in that before I send it 
off to iBatis.

Does this sound like a reasonable plan?

Re: best way to use a Map?

[Brandon Goodin <br...@gmail.com>]

Why not just create an ImageSizes table? The ImageSizes table would contain
| id | imageId | width | height | sizeKey |

Then you have a 1 to many relationship with your Image and you can use
queryForMap and make the sizeKey (which could be size1, size2, size3,
size4...) the key of the Map.

Additionally it would be helpful if you posted some of your code. Your
explanation is a bit abstract... an EnumMap?

Thanks,
Brandon Goodin

On 10/6/07, Rusty Wright <ru...@gmail.com> wrote:
>
>  They aren't the available sizes, but the actual size of each photo, so
> each photo could have different dimensions, depending on whether or not the
> user cropped it in Photoshop, the size the camera produces, etc.  It's
> random data that's more or less unique to each photo.  The SIZE1, SIZE2,
> etc. have within them the maximums; for example, SIZE1 might be 200 maximum
> width and height, SIZE4 could be 1024.  Those are hard coded in the enum
> (but I could store them elsewhere):
>
> public enum PhotoSizeBounds {
>     SIZE0(0), // original photo
>     SIZE1(200),
>     SIZE2(320),
>     SIZE3(640),
>     SIZE4(1024);
>
>     private final int max;
>
>     PhotoSizeBounds(final int _max) {
>         max = _max;
>     }
>
>     /**
>      * @return the maximum for this size.
>      */
>     public int getMax() {
>         return (max);
>     }
> }
>
> So when I display a picture at its SIZE1 size, I want its width and height
> because this is for a web app and I need those 2 values for the IMG tag.
>
> Ole Trenner wrote:
>
> (sorry if this message is a duplicate)
>
> Rusty Wright wrote:
>
>  I'm trying to figure out how to set up storing a Map of pairs of
> numbers.  I have a Photo object, and it has a Map of the different sizes
> in which the Photo is stored on disk.  The map keys are SIZE1, SIZE2,
> and SIZE3 (an enum; the map is an EnumMap).  The values in the Map are a
> simple object, ImageSize, with width and height fields. Each photo has
> its own sizes; no relationships and the widths and heights are
> essentially random values.
>
> I'm thinking that in my database, each row for a Photo will have columns
> size1_width, size1_height, size2_width, size2_height, etc.  Doesn't
> sound too elegant but I can't see any other way.
>
>  I'd prefer having a photo table without these sizes and storing them in
> a different table with a foreign key relation to the photos table
> instead. Something like that:
>
> photos:
>
> photo_id | photo_property_1 | photo_property_2 | ...
>
> sizes:
>
> size_id | photo_id - fk to photos(photo_id) | size_key | width | height
>
> This way a change of the available number of sizes has no influence on
> your database scheme.
>
>
>    I can't see any way to get these widths and heights into and out of the
> database other than to have getters and setters for each one. In order
> to not clutter my Photo class with those getters and setters I was
> thinking of making a PhotoDto data transfer object that does have the
> getters and setters and to wrap a Photo object in that before I send it
> off to iBatis.
>
>  When loading the photo objects you could join the photo table and the
> sizes table and use the groupBy attribute in the mapping to easily map
> the collection property (that is what the sizes map is).
>
> When storing you'd have to stick to two subsequent inserts (one for the
> sizes, one for the photo itself.
>
>
> Just my 2 ct...
> Cheers,
> Ole.
>
>
>

Re: best way to use a Map?

[Ole Trenner <ol...@googlemail.com>]

(sorry if this message is a duplicate)

Rusty Wright wrote:
> I'm trying to figure out how to set up storing a Map of pairs of
> numbers.  I have a Photo object, and it has a Map of the different sizes
> in which the Photo is stored on disk.  The map keys are SIZE1, SIZE2,
> and SIZE3 (an enum; the map is an EnumMap).  The values in the Map are a
> simple object, ImageSize, with width and height fields. Each photo has
> its own sizes; no relationships and the widths and heights are
> essentially random values.
> 
> I'm thinking that in my database, each row for a Photo will have columns
> size1_width, size1_height, size2_width, size2_height, etc.  Doesn't
> sound too elegant but I can't see any other way.


I'd prefer having a photo table without these sizes and storing them in
a different table with a foreign key relation to the photos table
instead. Something like that:

photos:

photo_id | photo_property_1 | photo_property_2 | ...

sizes:

size_id | photo_id - fk to photos(photo_id) | size_key | width | height

This way a change of the available number of sizes has no influence on
your database scheme.


> I can't see any way to get these widths and heights into and out of the
> database other than to have getters and setters for each one. In order
> to not clutter my Photo class with those getters and setters I was
> thinking of making a PhotoDto data transfer object that does have the
> getters and setters and to wrap a Photo object in that before I send it
> off to iBatis.


When loading the photo objects you could join the photo table and the
sizes table and use the groupBy attribute in the mapping to easily map
the collection property (that is what the sizes map is).

When storing you'd have to stick to two subsequent inserts (one for the
sizes, one for the photo itself.


Just my 2 ct...
Cheers,
Ole.