let the datafetcher resolve variable references (#205)

Author: Andy2003

core/src/main/kotlin/org/neo4j/graphql/Translator.kt

@@ -27,14 +27,13 @@ class Translator(val schema: GraphQLSchema) {
                     .filterIsInstance<Field>() // FragmentSpread, InlineFragment
                     .map { field ->
                         val cypher = toQuery(operationDefinition.operation, field, fragments, params, ctx)
-                        val resolvedParams = cypher.params.mapValues { toBoltValue(it.value, params) }
-                        cypher.with(resolvedParams) // was cypher.with(params)
+                        val resolvedParams = cypher.params.mapValues { toBoltValue(it.value) }
+                        cypher.with(resolvedParams)
                     }
             }
     }
 
-    private fun toBoltValue(value: Any?, params: Map<String, Any?>) = when (value) {
-        is VariableReference -> params[value.name]
+    private fun toBoltValue(value: Any?) = when (value) {
         is BigInteger -> value.longValueExact()
         is BigDecimal -> value.toDouble()
         else -> value

core/src/main/kotlin/org/neo4j/graphql/handler/BaseDataFetcher.kt

@@ -1,6 +1,7 @@
 package org.neo4j.graphql.handler
 
 import graphql.language.Field
+import graphql.language.VariableReference
 import graphql.schema.DataFetcher
 import graphql.schema.DataFetchingEnvironment
 import graphql.schema.GraphQLFieldDefinition
@@ -29,7 +30,12 @@ abstract class BaseDataFetcher(val fieldDefinition: GraphQLFieldDefinition) : Pr
             .withPrettyPrint(true)
             .build()
         ).render(statement)
-        return Cypher(query, statement.parameters, fieldDefinition.type, variable = field.aliasOrName())
+
+        val params = statement.parameters.mapValues { (_, value) ->
+            (value as? VariableReference)?.let { env.variables[it.name] } ?: value
+        }
+
+        return Cypher(query, params, fieldDefinition.type, variable = field.aliasOrName())
     }
 
     protected abstract fun generateCypher(variable: String, field: Field, env: DataFetchingEnvironment): Statement