In Lightning:datatable picklist will not list down dropdown values in Inline Edit mode, so i decided to go with modal to show picklist dropdown values for selection in modal Edit mode.
Post deployment Instructions : Once deployed, drag and drop the component to Account record by editing the page in Lightning Mode.
Business use case of this component :
Salesforce end users can have an option of adding contact emails directly from the Account. To do this i created a Lightning component that will be accessible from an account and this component will show ALL contacts related to that Account.
Display fields are First Name,Last Name and Phone as read-only fields and the email and email type (new field) as
editable fields, Also the new custom field “email type” is a picklist field with values: Business, Personal, Other.
Client level Validation : If you enter an email, the email type is mandatory for that contact.
For complete Source Code: https://github.com/dineshdk/lightning-datatable-with-picklist-select-powered-in-Edit-Mode
lwc datatable source code :- http://www.sfdcpanda.com/lightning-web-component-datatable/
Dynamic picklist with default value selected as radio buttons :- http://www.sfdcpanda.com/picklist-values-radio-buttons-default-value-selected-lightning-component/