From 6f786518cd2a22799e09b998756499bae7d41d8a Mon Sep 17 00:00:00 2001
From: Jatin Dev <64803093+JatinDevDG@users.noreply.github.com>
Date: Wed, 10 Mar 2021 22:53:35 +0530
Subject: [PATCH] fix(GRAPHQL): Added support for exact index on field having
 @id directive. (#7534)

Currently we add hash index on a field of type String! @id by default. And as index exact and hash are not compatible , user can't add exact index on such field and can't take advantage of comparator functions like lt,le,gt,ge.

To allow this we now changing that behavior, i.e. for a field of type String! @id @search(by:[exact]) , we don't generate default hash index and only generate exact index.

(cherry picked from commit 195f2474cca437027fe1ad6868f7bcb7b645eb0f)
---
 graphql/schema/dgraph_schemagen_test.yml      | 19 +++++++++++++++
 graphql/schema/gqlschema.go                   | 10 ++------
 graphql/schema/gqlschema_test.yml             |  6 +++++
 graphql/schema/schemagen.go                   | 24 ++++++++++---------
 .../input/field-with-id-directive.graphql     |  3 ++-
 .../output/field-with-id-directive.graphql    |  4 ++--
 6 files changed, 44 insertions(+), 22 deletions(-)

diff --git a/graphql/schema/dgraph_schemagen_test.yml b/graphql/schema/dgraph_schemagen_test.yml
index 3555b13d581..0f9796d9ee0 100644
--- a/graphql/schema/dgraph_schemagen_test.yml
+++ b/graphql/schema/dgraph_schemagen_test.yml
@@ -494,6 +494,25 @@ schemas:
       }
       B.correct: bool @index(bool) .
 
+  - name: "Field with @id directive and a exact arg in search directive generates correct schema."
+    input: |
+      interface A {
+        id: String! @id @search(by: [exact])
+      }
+      type B implements A {
+        correct: Boolean @search
+      }
+    output: |
+      type A {
+        A.id
+      }
+      A.id: string @index(exact) @upsert .
+      type B {
+        A.id
+        B.correct
+      }
+      B.correct: bool @index(bool) .
+
   -
     name: "Field with reverse predicate in dgraph directive adds @reverse to predicate."
     input: |
diff --git a/graphql/schema/gqlschema.go b/graphql/schema/gqlschema.go
index 0e672f2ded1..7156769c3ff 100644
--- a/graphql/schema/gqlschema.go
+++ b/graphql/schema/gqlschema.go
@@ -1648,14 +1648,8 @@ func addHashIfRequired(fld *ast.FieldDefinition, indexes []string) []string {
 	id := fld.Directives.ForName(idDirective)
 	if id != nil {
 		// If @id directive is applied along with @search, we check if the search has hash as an
-		// arg. If it doesn't, then we add it.
-		containsHash := false
-		for _, index := range indexes {
-			if index == "hash" {
-				containsHash = true
-			}
-		}
-		if !containsHash {
+		// arg. If it doesn't and there is no exact arg, then we add hash in it.
+		if !x.HasString(indexes, "hash") && !x.HasString(indexes, "exact") {
 			indexes = append(indexes, "hash")
 		}
 	}
diff --git a/graphql/schema/gqlschema_test.yml b/graphql/schema/gqlschema_test.yml
index d9fa401c169..f9eb7673f4b 100644
--- a/graphql/schema/gqlschema_test.yml
+++ b/graphql/schema/gqlschema_test.yml
@@ -2838,6 +2838,12 @@ valid_schemas:
         f2: String! @id
       }
 
+  - name: "field with @id directive can have exact index"
+    input: |
+      type X {
+        f1: String! @id @search(by:[exact])
+      }
+
   - name: "Type implements from two interfaces where both have ID"
     input: |
       interface X {
diff --git a/graphql/schema/schemagen.go b/graphql/schema/schemagen.go
index fc505b054b6..9e97a29f43b 100644
--- a/graphql/schema/schemagen.go
+++ b/graphql/schema/schemagen.go
@@ -637,6 +637,16 @@ func genDgSchema(gqlSch *ast.Schema, definitions []string) string {
 					var indexes []string
 					upsertStr := ""
 					search := f.Directives.ForName(searchDirective)
+					if search != nil {
+						arg := search.Arguments.ForName(searchArgs)
+						if arg != nil {
+							indexes = append(indexes, getAllSearchIndexes(arg.Value)...)
+						} else {
+							indexes = append(indexes, supportedSearches[defaultSearches[f.Type.
+								Name()]].dgIndex)
+						}
+					}
+
 					id := f.Directives.ForName(idDirective)
 					if id != nil || f.Type.Name() == "ID" {
 						upsertStr = "@upsert "
@@ -646,17 +656,9 @@ func genDgSchema(gqlSch *ast.Schema, definitions []string) string {
 						case "Float":
 							indexes = append(indexes, "float")
 						case "String", "ID":
-							indexes = append(indexes, "hash")
-						}
-					}
-
-					if search != nil {
-						arg := search.Arguments.ForName(searchArgs)
-						if arg != nil {
-							indexes = append(indexes, getAllSearchIndexes(arg.Value)...)
-						} else {
-							indexes = append(indexes, supportedSearches[defaultSearches[f.Type.
-								Name()]].dgIndex)
+							if !x.HasString(indexes, "exact") {
+								indexes = append(indexes, "hash")
+							}
 						}
 					}
 
diff --git a/graphql/schema/testdata/schemagen/input/field-with-id-directive.graphql b/graphql/schema/testdata/schemagen/input/field-with-id-directive.graphql
index 9f9bfaa58c9..19676b1d59e 100644
--- a/graphql/schema/testdata/schemagen/input/field-with-id-directive.graphql
+++ b/graphql/schema/testdata/schemagen/input/field-with-id-directive.graphql
@@ -13,5 +13,6 @@ type Author {
 }
 
 type Genre {
-    name: String! @id
+    # This will add exact index on name field, overwriting the default "hash" index for field of type "String! @id".
+    name: String! @id @search(by: [exact])
 }
diff --git a/graphql/schema/testdata/schemagen/output/field-with-id-directive.graphql b/graphql/schema/testdata/schemagen/output/field-with-id-directive.graphql
index 87397d9f074..953cd61e262 100755
--- a/graphql/schema/testdata/schemagen/output/field-with-id-directive.graphql
+++ b/graphql/schema/testdata/schemagen/output/field-with-id-directive.graphql
@@ -18,7 +18,7 @@ type Author {
 }
 
 type Genre {
-	name: String! @id
+	name: String! @id @search(by: [exact])
 }
 
 #######################
@@ -430,7 +430,7 @@ input AuthorRef {
 }
 
 input GenreFilter {
-	name: StringHashFilter
+	name: StringExactFilter
 	has: [GenreHasFilter]
 	and: [GenreFilter]
 	or: [GenreFilter]