How to store nested document as String in elastic search - elasticsearch

Question

Context:
1) We are building a CDC pipeline (using kafka & connect framework)
2) We are using debezium for capturing mysql Tx logs
3) We are using Elastic Search connector to add documents to ES index
Sample change event generated by Debezium:
{
"source" : {
"before" : {
"Id" : 97,
"name" : "Northland",
"code" : "NTL",
"country_id" : 6,
"is_business_mapped" : 0
},
"after" : {
"Id" : 97,
"name" : "Northland",
"code" : "NTL",
"country_id" : 6,
"is_business_mapped" : 1
},
"source" : {
"version" : "0.7.5",
"name" : "__",
"server_id" : 252639387,
"ts_sec" : 1547805940,
"gtid" : null,
"file" : "mysql-bin-changelog.000570",
"pos" : 236,
"row" : 0,
"snapshot" : false,
"thread" : 614,
"db" : "bazaarify",
"table" : "state"
},
"op" : "u",
"ts_ms" : 1547805939683
}
What we want :
We want to visualize only 3 columns in kibana :
1) before - containing the nested JSON as string
2) after - containing the nested JSON as string
3) source - containing the nested JSON as string
I can think below possibilities here :
a) Either converting nested JSON as string
b) Combining column data in elastic search
I am a newbie to elastic search . Can someone please guide me how to do that.
I tried defining custom mapping as well but it is giving me exception.

Answer 1

You can always view your document as a Raw JSON in Kibana.
You don't need to manipulate it before indexing in elastic.
As this is related to visualization, handle this in Kibana only.
Check this link for a screenshot.
Refer this to add the columns which you want to see onto the results

Answer 2

I don't fully understand your use case, but if you would like to turn some json's to their representing strings, then you can use logstash for that, or even Elasticsearch ingest capabilities to convert an object (json) to a string.
From the link above, an example:
PUT _ingest/pipeline/my-pipeline-id { "description": "converts the
content of the id field to an integer", "processors" : [
{
"convert" : {
"field" : "source",
"type": "string"
}
} ] }