Cannot assign to struct field in a map

For those looking for a simpler example:

This is wrong:

type myStruct struct{
   Field int
}

func main() {
   myMap := map[string]myStruct{
        "key":{
            Field: 1,
        },
   }

   myMap["key"].Field = 5
}

Because myMap["key"] is not “addressable”.

This is correct:

type myStruct struct{
   Field int
}

func main(){
   myMap := map[string]myStruct{
       "key":{
           Field: 1,
       },
   }

   // First we get a "copy" of the entry
   if entry, ok := myMap["key"]; ok {

       // Then we modify the copy
       entry.Field = 5
    
       // Then we reassign map entry
       myMap["key"] = entry
   }

   // Now "key".Field is 5
   fmt.Println(myMap) // Prints map[key:{5}]
}

Here you have a working example.