I have a class like class `someClass(val id : String, val imageResourceId: Int)`. Basically I want t...

# android

[Alin B.]

I have a class like class someClass(val id : String, val imageResourceId: Int). Basically I want to set the drawable id as the source of the image resource to show in the app. However, resIds may change upon adding new resources so I end up with a database which hosts wrong ids. One way I can think of is adding the icons in the assets folder and user Glide to load from there. Any other thoughts?

[Can Orhan]

Have you tried this api? https://developer.android.com/reference/android/content/res/Resources.html#getIdentifier(java.lang.String,%20java.lang.String,%20java.lang.String)

You could store the resource name instead?

[gildor]

But why do you worry about Id changes, Android automatically generate all of them in R.class, so you can use this fields directly and do not worry that I'd will be changed

[Can Orhan]

@gildor From what I understood, the generated ID is being stored. When the build changes the id, the ones in the DB become stale

[Alin B.]

Indeed, I may store the resource name, but then each time I need it, I need to search it.

[Can Orhan]

@Alin B. Sorry - Not sure I understand the concern.

[Alin B.]

I mean each time I want to display it I need to do resources.getIdentifier(name, "drawable", "your.package.name")

[gildor]

Just cache it, if you need this many times, I still not completely understand your case

[gildor]

Do you serialize this value as Can supposed?

[Alin B.]

I am at the point of deciding how to store the value. To better put let me add another example table categories with id, name and icon. The icon is included in the app and I need to decide what to store in the icon field.

[Alin B.]

I can store "ic_category_one" and then use getIdentifier with that name and load it with Glide

[gildor]

To store value in database?

[Alin B.]

other way is to put it in assets and load it with glide `"file:///android_asset/ic_category_one.jpg"

[Alin B.]

yes, what to store in the db as icon value in order to be easy to retrieve it when I want to show it

[gildor]

I would rather use some custom id for icon and map it to actual reaource on runtime

[gildor]

For example you have 2 types of icon: home and work

[Can Orhan]

^I was thinking the same thing but it can be annoying to maintain something like that.

[gildor]

I would just save this id in database and map this id to actual resource like:
when(iconId) {
"home" -> R.drawable.ic_home_red_24dp
}

[Alin B.]

but in this case I could use when (category.name), no?

[gildor]

Otherwise you can one day decide to change icon (like on ic_dead_star_black_36dp, and of course you want to have proper name for icon not some hardcoded one

[gildor]

Also it's much more flexible, one day you want to have dynamic icona and so on

[gildor]

Yes,. you can use when or even just Map<String, Int>

[Alin B.]

so maybe have a get() for imageResId which has a when based on the name

[gildor]

To be honest I don't think it's too much tedious, depends on amount of icons of course

[gildor]

But why do you need imageResId than?

[Alin B.]

I don't anymore if I go with your approach, just a getter to return the drawable id I want based on the name

[gildor]

Again, depends on case, for example we have emoju drawables and of course we do not map them all, but we use unicode id of emoji to generate resource I'd and llokup by name

[gildor]

But if you have limited set of icons I would rather use manual mapping

[gildor]

Also you probably have some list of available options in UI, so would be good to convert this list to map of type -> drawable

[gildor]

We actually also use this in case of emoji

[Alin B.]

I am talking about a few icons, 5 maybe. To be sure understand you right, have something like

class Category(val id:Int, val name, val imageResId:Int){
    val imageResId:Int
	get()=when(...)
}

[Alin B.]

pseudo-code I still don't know Kotlin too well 🙂

[gildor]

If categories are not dynamic, just use enum for category and serialize it as enum name, will be type safe, declarative and flexible
Also no need to serialize all unnecessary data to database if you already declare it

[Alin B.]

ok, digging enum in kotlin... everything is new to me.
This:

enum class Category(val name:String){
    HOME("home"),
    WORK("work")
}

[gildor]

Yes, and also property for icon

[gildor]

And store in db just enum name

[Alin B.]

This is a really great answer. Thank you very much!

[gildor]

Kotlin enums implementation almost identical to java, so no real difference

[Alin B.]

How about for a scenario where I have products and the user can pick a generic icon from a set of icons to a new added product. In this case I need to store something in the database as I insert the product

[Alin B.]

kind of the same really, as icons are in a enum and store the enum name

[gildor]

Also one more good thing about enums is that you can get a full list of possible options and for example iterate them

[gildor]

Yes, the same, just represent each category as item of enum, can be useful not only for icons, but for some other cases (like category config), when user choose category for product use this enum and store to database

[gildor]

Thumb of rule: use enum for any ENUMerable static data. If you have something dynamic than you need something else, can use db to store settings, but for thing like static set of icons I would still use enums

[Alin B.]

I did a little coding to get a hold of the idea, here is how I think it could be

enum class CategoryType(val id: String, val imageResId: Int) {
    HOME("home", R.id.ic_home),
    WORK("work", R.id.ic_work)
}

then when I use it

val categoryType = CategoryType.valueOf(item.dbCategoryValue)

val imageResIdToLoad = categoryType.imageResId

[Alin B.]

however, I am not sure that I need the val id

[Alin B.]

since I can store HOME or WORK in db

[Can Orhan]

Could you get away with not using the id param instead?

enum class CategoryType(val id: Int) {
        HOME(R.id.ic_home),
        WORK(R.id.ic_work)
    }
CategoryType.valueOf("HOME").id

[Alin B.]

That what I said above, the id seemed not needed

[Can Orhan]

Ah sorry!

[Alin B.]

No need to, thanks for the code sample.

[Alin B.]

@gildor, @Can Orhan thank you very much for your time and info. It sure came out a solution which I did not have in mind when asked.

[Can Orhan]

Happy to help

[gildor]

Also if you use some mapper of db to objects, you can just use enums, probably your mapper can do that automatically.
You mentioned Room in one of other threads, you can use enums with room without manual unwrapping them from string

[Alin B.]

Yeah I am using Room

[Alin B.]

not sure what you mean by without unwrapping

[Alin B.]

you mean, use in @Query CategoryType as a field?

[gildor]

Sure

[gildor]

If you want to use it as field in some other data, like in your "product", example

[Alin B.]

Awesome, thank you very much for you help.