Fix has pagination when predicate is queried with @lang

[ashish-goswami]

Fixes #4282

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This change is 

[animesh2049]

Reviewed 2 of 2 files at r2.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @golangcibot, @mangalaman93, @manishrjain, and @pawanrawal)

[pawanrawal]

Reviewable status: all files reviewed, 4 unresolved discussions (waiting on @ashish-goswami, @golangcibot, @mangalaman93, and @manishrjain)

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query/query4_test.go, line 602 at r2 (raw file):

// func TestHasFirstLangPredicate(t *testing.T) {
// 	query := `{
// 		q(func:has(name@lang), orderasc: name, first:5) {

This won't work but a test case which is just calling the has function on a predicate with a lang and first should work? Could we add that please?

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worker/task.go, line 2096 at r2 (raw file):

	lang := langForFunc(q.Langs)
	needFiltering := needsStringFiltering(srcFn, q.Langs, q.Attr)
	checkInclusion := func(uid uint64) error {

Add some comments that what we are fetching the value for the uid + predicate@lang here before deciding if we want to include the uid in the result.

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worker/task.go, line 2101 at r2 (raw file):

		}

		_, err := qs.getValsForUID(q.Attr, lang, uid, q.ReadTs)

Since this would only be called if there is a language, we don't need the extra logic in getValsForUID corresponding to lang == ""

[ashish-goswami]

Dismissed @golangcibot from a discussion.
Reviewable status: 1 of 2 files reviewed, 3 unresolved discussions (waiting on @animesh2049, @lang, @mangalaman93, @manishrjain, and @pawanrawal)

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query/query4_test.go, line 602 at r2 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

This won't work but a test case which is just calling the has function on a predicate with a lang and first should work? Could we add that please?

First might return result in any order. Hence I won't be able to compare it. I have added test for count though.

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worker/task.go, line 2096 at r2 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

Add some comments that what we are fetching the value for the uid + predicate@lang here before deciding if we want to include the uid in the result.

Done.

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worker/task.go, line 2101 at r2 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

Since this would only be called if there is a language, we don't need the extra logic in getValsForUID corresponding to lang == ""

We need it in case predicate supports @lang. When lang is "", we need to get all uids which does not have @lang(there might be no posting for this). We predicate is list, this function won't be called from
handleHasFunction.

[pawanrawal]

Reviewed 1 of 2 files at r2, 1 of 1 files at r3.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @ashish-goswami, @mangalaman93, and @manishrjain)

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query/query4_test.go, line 633 at r3 (raw file):

func TestHasCountPredicateWithLang(t *testing.T) {
	query := `{
		q(func:has(name@en), first: 5) {

Could we use a higher number here please which is equal to number of nodes which have name@en?

[ashish-goswami]

Reviewable status: 1 of 2 files reviewed, 1 unresolved discussion (waiting on @animesh2049, @mangalaman93, @manishrjain, and @pawanrawal)

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query/query4_test.go, line 633 at r3 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

Could we use a higher number here please which is equal to number of nodes which have name@en?

Done.

[manishrjain]

Reviewable status: 1 of 2 files reviewed, 1 unresolved discussion (waiting on @animesh2049, @mangalaman93, @manishrjain, and @pawanrawal)