Would someone give an explanation of how to modify the data of a fox?

Question

Using Minecraft 1.14, I would like to use the /data command to change a baby fox's age. There are three other foxes in the world, and I would not like any of them changed or modified. I've been trying to figure this out for a while, and the closest I've gotten is:

/data merge entity @e[type=fox,limit=1,nbt={Age:-1}] {Age:1}

however that doesn't seek to work. It says on the wiki that when a fox is a baby, its age is negative, but when it's an adult, it's age is 0 or above. I tried to implement this, but I'm not sure exactly how to figure it out in detail. Can someone explain?

Answer 1

The Age tag represents how many ticks the mob has until it grows up (if it's a baby) or how many ticks until it can breed (if it's an adult). Therefore, baby foxes can have any less than 0, not just -1.

As you cannot directly check if an NBT tag is greater/less than a value, you need to store the Age in a scoreboard first:

/scoreboard objectives add age dummy
/execute as @e[type=fox] run store result score @s age run data get entity @s Age

Then you can select the first fox with an age ≤ -1:

execute as @e[type=fox,limit=1,scores={age=..-1}] run data merge entity @s {Age:1}