Allow to filter relation by interface

core/src/main/kotlin/org/neo4j/graphql/parser/QueryParser.kt

@@ -3,7 +3,6 @@ package org.neo4j.graphql.parser
 import graphql.language.*
 import graphql.schema.GraphQLFieldDefinition
 import graphql.schema.GraphQLFieldsContainer
-import graphql.schema.GraphQLObjectType
 import org.neo4j.cypherdsl.core.*
 import org.neo4j.cypherdsl.core.Node
 import org.neo4j.graphql.*
@@ -69,14 +68,14 @@ class RelationPredicate(
 ) : Predicate<RelationOperator>(op, queryField, normalizeName(fieldDefinition.name, op.suffix.toCamelCase()), index) {
 
     val relationshipInfo = type.relationshipFor(fieldDefinition.name)!!
-    val relNode: Node = CypherDSL.node((fieldDefinition.type.inner() as? GraphQLObjectType)?.label()!!)
+    val relNode: Node = CypherDSL.node(fieldDefinition.type.getInnerFieldsContainer().label())
 
     fun createRelation(start: Node): Relationship = relationshipInfo.createRelation(start, relNode)
 
     fun createExistsCondition(propertyContainer: PropertyContainer): Condition {
         val relation = createRelation(propertyContainer as? Node
                 ?: throw IllegalStateException("""propertyContainer is expected to be a Node but was ${propertyContainer.javaClass.name}"""))
-       val  condition = CypherDSL.match(relation).asCondition()
+        val condition = CypherDSL.match(relation).asCondition()
         return when (op) {
             RelationOperator.NOT -> condition
             RelationOperator.EQ_OR_NOT_EXISTS -> condition.not()

core/src/test/resources/issues/gh-210.adoc

@@ -0,0 +1,67 @@
+:toc:
+
+= Github Issue #210: Nested filters are not working
+
+== Schema
+
+[source,graphql,schema=true]
+----
+interface Period {
+   id: String!
+   value: Int!
+   in: [Period] @relation(name: "IN_PERIOD", direction: OUT)
+}
+
+type Week implements Period {
+   id: String!
+   value: Int!
+   in: [Period] @relation(name: "IN_PERIOD", direction: OUT)
+}
+----
+
+== Configuration
+
+.Configuration
+[source,json,schema-config=true]
+----
+{
+  "capitalizeQueryFields": true
+}
+----
+
+== Test
+
+.GraphQL-Query
+[source,graphql]
+----
+{
+   Week(
+    filter: {
+      in: { value:2020 }
+    }
+  )
+  {
+    id
+  }
+}
+----
+
+.Cypher Params
+[source,json]
+----
+{
+  "filterWeekPeriodValue" : 2020
+}
+----
+
+.Cypher
+[source,cypher]
+----
+MATCH (week:Week)
+WHERE all(filterWeekPeriodCond IN [(week)-[:IN_PERIOD]->(filterWeekPeriod:Period) | filterWeekPeriod.value = $filterWeekPeriodValue]
+WHERE filterWeekPeriodCond)
+RETURN week {
+	.id
+} AS Week
+----
+