i'm buying dinner ....

[squarezebra]

Ok, this quote from "introduction to modern Japanese" states that the subject is buying dinner for himself and his friend because today he has an unsual amount of money(apparently) (at least thats the context) :

今日はめずらしくたくさんお金を持っているので私がごちそうします

Now then, the question... Given that it doesn't contain the verb to buy (買う）anywhere within that phrase is it idiomatic?
Like, if I said to my friend "i'm doing dinner" it might be understood that i'm inviting him/her to dinner ... is that how this works here? 私がごちそうします　－im doing dinner, or dinner is on me?

Thanks

[NocturnalOcean]

ごちそうする means to treat someone(to dinner).

[squarezebra]

ahhh, thanks! That now makes much more sense!

[keatonatron]

"I've got lots of money, for once, so tonight is on me"

[hyperconjugated]

This ごちそうします applies only to something eatable/drinkable, right?

I mean you can ごちそうします drinks for your friends but couldn't say it in a sentence like "Let's go to movies, my treat!"

[keatonatron]

This ごちそうします applies only to something eatable/drinkable, right?

Technically I think it can be used for anything, but you only hear it said about edible items.

[Harisenbon]

Technically I think it can be used for anything, but you only hear it said about edible items.

And about talks...
My brain is fried, so I can't think about what you say in english, but for example if you talk for a while the other person may say ごちそうさま～ after listening.