graphql: Introduce @cascade in GraphQL

[abhimanyusinghgaur]

Fixes #4789.
Fixes #GRAPHQL-277.

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[pawanrawal]

Reviewed 40 of 40 files at r1.
Reviewable status: all files reviewed, 5 unresolved discussions (waiting on @abhimanyusinghgaur and @MichaelJCompton)

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graphql/e2e/common/query.go, line 1595 at r1 (raw file):

							},{
								"reputation": 4.6,
								"posts": []

You should try and fetch title as well for this query and then because you have @cascade on posts it should not be returned.

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graphql/resolve/query_test.yaml, line 658 at r1 (raw file):

  gqlquery: |
    query {
      getAuthor(id: "0x1") @cascade {

Is @cascade allowed in Dgraph on predicates without children? If not, then what happens in that case from GraphQL?

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graphql/resolve/query_test.yaml, line 706 at r1 (raw file):

      queryAuthor {
        dob
        posts @cascade {

Also add a test case where the directive is both on root and a field below.

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graphql/schema/gqlschema.go, line 121 at r1 (raw file):

directive @custom(http: CustomHTTP) on FIELD_DEFINITION
directive @remote on OBJECT | INTERFACE
directive @cascade on FIELD

So the directive isn't allowed while querying interfaces?

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graphql/schema/wrappers.go, line 1162 at r1 (raw file):

			continue
		}
		if m.Cascade() && !f.Cascade() {

Are we adding the directive to the field here from the mutation so that it is applied to the query after?

[abhimanyusinghgaur]

Reviewable status: all files reviewed, 5 unresolved discussions (waiting on @MichaelJCompton and @pawanrawal)

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graphql/e2e/common/query.go, line 1595 at r1 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

You should try and fetch title as well for this query and then because you have @cascade on posts it should not be returned.

Done.

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graphql/resolve/query_test.yaml, line 658 at r1 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

Is @cascade allowed in Dgraph on predicates without children? If not, then what happens in that case from GraphQL?

It is allowed on such predicates. I checked, it didn't give any errors and worked fine.

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graphql/resolve/query_test.yaml, line 706 at r1 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

Also add a test case where the directive is both on root and a field below.

Done.

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graphql/schema/gqlschema.go, line 121 at r1 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

So the directive isn't allowed while querying interfaces?

Doesn't matter what type is returned I guess.
As all the queries/mutations are basically fields of type Query and type Mutation, so cascade can be applied on them, and any field in their selection set. So, anything where @cascade is going to be applied is going to be a field.

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graphql/schema/wrappers.go, line 1162 at r1 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

Are we adding the directive to the field here from the mutation so that it is applied to the query after?

Yes, so that if @cascade was given on mutation itself, then it should get applied for the query which gets executed to fetch the results of that mutation.

[pawanrawal]

Reviewed 3 of 3 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @MichaelJCompton)

[MichaelJCompton]

Just to master for this one - it's a new feature, so it won't go into 20.03

Can you make sure you mark the milestone on the github issue and the fix version on the jira ticket at 20.07...

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @abhimanyusinghgaur)

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graphql/resolve/mutation_query_test.yaml, line 157 at r2 (raw file):

    gqlquery: |
      mutation {
        ADD_UPDATE_MUTATION @cascade {

nice

[abhimanyusinghgaur]

Done.

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @MichaelJCompton)

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graphql/resolve/mutation_query_test.yaml, line 157 at r2 (raw file):

Previously, MichaelJCompton (Michael Compton) wrote…

nice

Done.