VRL move root to new field

[alexeynl]

Is there any good way to move root (.) of the event to new field?

I tried the following

.newfield = del(.)

but next following assingment

.field1.subfield1 = "value"

get me the error

"querying a field of a non-object type is unsupported"

I understand that i can copy root to new field and next remove all others, but this looks not efficient way to do such simple thing...

[pront]

👋 Hi @alexeynl, see this example. It assigns the whole top level object to a new path.

[alexeynl]

now can use path syntax

# now can use path syntax
.field.subfield = "value1"

No, you can't! This is main problem in this case! Try to replace:

.field.subfield = "value1" ->  .field.subfield.subsubfield = "value1"

in you example and you will get the same error querying a field of a non-object type is unsupported!

VRL Playground

[pront]

Hey @alexeynl, I understand why this might confusing. I tried to collect all these ideas here. Hope this helps. You will have to instantiate an object {} to avoid the error.

[alexeynl]

It looks like i found the reason why it is happened from the desing point of view. Please check this VRL Playground example, i have change your previouse example slightly.

If you look at root definition before del(.):

"first_root_type": {
  "object": {
	  "newfield": {
		  "bytes": true
	  }
  },
  "object_unknown_infinite": { <<---- EXISTS
	  "any": true
  }
},

and after

"second_root_type": {
"object": {
	"newfield": {
		"object": {},
		"object_unknown_infinite": { <<<IT IS HERE NOW!
			"any": true
		}
	}
} <<<---- OBJECT_UNKNOWN_INFINITE DOES NOT EXIST FOR ROOT!

you can see that property object_unknown_infinite

"object_unknown_infinite": {
	"any": true
}

is missing for root in second case!

Is this expected behaviour???

[alexeynl]

Difenitly i found the reason and my previouse explanation is right. This Playgound is a new proof:

.oldroot = del(.)

#try to use path syntax in new root like this
.field.subfield.subsubfield = "" << --- comment this and you look at the magic)
#will get error querying a field of a non-object type is unsupported

#but no error for old root!
.oldroot.field.subfield.subsubfield = "value"

[jszwedko]

This is admittedly a bit subtle, but when you do del(.) that sets . to null and so you can no longer access fields on it without resetting it to {} (an object).