Add ability to expand only on certain types.

[martinmr]

Instead of doing expand(all), this change introduces expand(Type1, Type2) syntax to
expand only on certain types.

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[pullrequest]

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[martinmr]

There are some issues with the query code that came up while making this change.

• Language tags are only expanded when using expand(_all_). I am not sure if this is the desired behavior.
• The following test is failing because the uid of the node is shown. This does not happen when using expand(_all_). Removing the uid part from the query makes the test pass but I am not sure why there's a difference between doing expand(_all_) and expand(<list of all the types>)

func TestTypeExpandMultipleExplicitTypes(t *testing.T) {
	query := `{
		q(func: eq(make, "Toyota")) {
			expand(CarModel, Object) {
                           uid
                         }
		}
	}`
	js := processQueryNoErr(t, query)
	require.JSONEq(t, `{"data": {"q":[
		{"name": "Car", "make":"Toyota","model":"Prius", "year":2009}]}}`, js)
}

@pawanrawal could you take a look at the second item. I am not sure why the uid of the node is being returned along all the other predicates.

[pullrequest]

The structure looks sound but have some questions pertaining to the use of pointer semantics in the parseTypeList function.

It appears that the lex.ItemIterator is never mutated. Is the reason you are using pointers here due to the fact that the cost of copying is high or just a code pattern in this project?

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[pawanrawal]

I had a look at it but couldn't find immediately why. I suppose what could be happening here is that the uid is being somehow added at the same level as other predicates instead of a child. It would require time for me to debug and I am busy with other things right now. If you can't figure it out, file it as a bug and then I or someone else could have a proper look later.

[martinmr]

No worries. I was hoping it was something obvious I was missing. I'll take a closer look soon.

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[martinmr]

I found the root cause of the weird issue I was seeing (the parser code was incorrectly swallowing a { character. PR should be ready to review now.

Reviewable status: 0 of 7 files reviewed, 1 unresolved discussion

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query/query.go, line 2648 at r2 (raw file):

			}
			sg := req.Subgraphs[idx]

remove this line

[pawanrawal]

Would be get to merge the other PRs to master and merge master into this branch first.

Reviewed 2 of 7 files at r1, 4 of 5 files at r2, 1 of 1 files at r3.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @manishrjain and @martinmr)

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query/query.go, line 2648 at r2 (raw file):

Previously, martinmr (Martin Martinez Rivera) wrote…

remove this line

Why?

[martinmr]

I will merge the other PRs first since this is a new feature.

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @manishrjain)

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query/query.go, line 2648 at r2 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

Why?

Extra line I added. I just wrote a comment so I wouldn't forget.

[manishrjain]

One comment about the test case.

Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @martinmr)

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query/query4_test.go, line 345 at r3 (raw file):

		q(func: eq(make, "Toyota")) {
			expand(Object) {
				uid

Remove this.

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query/query4_test.go, line 357 at r3 (raw file):

		q(func: eq(make, "Toyota")) {
			expand(CarModel, Object) {
				uid

At least one example with expand(Type) which has a child node whose uid can be retrieved.

[martinmr]

Reviewable status: 0 of 7 files reviewed, 2 unresolved discussions (waiting on @manishrjain and @pawanrawal)

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query/query4_test.go, line 345 at r3 (raw file):

Previously, manishrjain (Manish R Jain) wrote…

Remove this.

Done.

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query/query4_test.go, line 357 at r3 (raw file):

Previously, manishrjain (Manish R Jain) wrote…

At least one example with expand(Type) which has a child node whose uid can be retrieved.

Done.