I have played with google analytic tool and found out the keywords can be found by selecting:
Conversions > Ecommerce > Sales Performance > NEW SEGMENT[ paid traffic ] > APPLY From Secondary Dimension > Advertising > Matched Search Query
Matched Search Query ( Gives exact search phrase used by customer )
Keyword ( Keywords group that it matched under a campaign )
Many options are available, you can test yourself. :)
But real thing was how to fetch this report using the metrics and dimensions via the API calls.
I used query explorer, tried different combinations at:
https://ga-dev-tools.appspot.com/query-explorer/
So in my case i needed transaction id and keywords ,the combinations should be :
Metrics:
- ga:transactions (Transactions)
Dimensions:
- ga:transactionId
- ga:keyword
- ga:adGroup
- ga:adMatchType
- ga:adMatchedQuery
- ga:adDestinationUrl
- ga:sourceMedium
There can be many other options to select from the Metrics and Dimensions, correct combination selection is something to figure out, i used help from:
https://developers.google.com/analytics/devguides/reporting/core/dimsmets#mode=web&cats=ecommerce
Hope this helps, if someone wants to share more knowledge, please do :)