implement deleteEdge store updater directive

[zth]

This supersedes #3148 which I've now closed.

This implements a new declarative for updating the store declaratively after mutations called @deleteEdge. As the name hints at, this particular directive allows you to remove a node's edge from the provided connections. Please note that this directive does not delete the node, only edge(s) for the node. There's @deleteRecord already for deleting a record, which can be combined with this directive.

It's intended to be used like this:

mutation DeleteComment($input: DeleteCommentInput!, $connections: [String!]!) {
  deleteComment(input: $input) {
    deletedCommentId @deleteEdge(connections: $connections)
    # This will delete any edge for the node with id `deletedCommentId` from the 
    # connections provided through `$connections`
  }
}

It works for single IDs (as demonstrated above) as well as a list of IDs.

[zth]

cc @tyao1

[tyao1]

Awesome! Thanks for implementing this!

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[facebook-github-bot]

@tyao1 merged this pull request in 01d65b3.