Uploading nested csv giving error- 0: object mapping for [comments] tried to parse field [comments] as object, but found a concrete value

Hi! I am trying to upload some data to elastic through a csv file which has multiple fields, out of which one is a nested field.
The mapping i defined is as follows-

"comments": {
"type": "nested",
"properties":{
"name":{
"type":"keyword"},
"rating":{
"type":"long"}
}

And the csv looks like-

image

The error I'm getting is-
0: object mapping for [comments] tried to parse field [comments] as object, but found a concrete value

Am i using the wrong format somewhere? Fairly new to elastic, any help would be greatly appreciated

How do you try to upload this? Via the csv file import? My high level guess is, that your JSON is treated as a string and thus this is failing.