How to update values of nested association using AssociateTo?

Question

Saying we have an association:

asc = <|"A" -> <|"a" -> 1, "b" -> 2, "c" -> 3|>|>;

I want to updated values of "A". I have tried doing:

AssociateTo[
  asc, 
  asc["A"][#] -> If[asc["A"][#] === 1, 0 , asc["A"][#]] & /@ {"a", "b", "c"}]

<|"A" -> <|"a" -> 1, "b" -> 2, "c" -> 3|>, 1 -> 0, 2 -> 2, 3 -> 3|>

But this just adds valuesst to the association instead of adding to "A"

How can I update the values in "A" using AssociateTo?

Answer 1

One possibility would be the simple

asc["A"]["a"] = 99;

As @m_goldberg commented this can be shortened to

asc["A", "a"] = 99;

To change several keys:

asc[[1]][[2 ;; 3]] = 4

Answer 2

I have came up with a solution:

In[1]:= asc = <|"A" -> <|"a" -> 1, "b" -> 2, "c" -> 3|>|>;
Module[{tmp = asc["A"]},
 AssociateTo[tmp, # -> tmp[#] + 1 & /@ {"a"}];
 AssociateTo[asc, "A" -> tmp]
 ]

Out[2]= <|"A" -> <|"a" -> 2, "b" -> 2, "c" -> 3|>|>