some docs about how type in ESI works plus test

andimarek · andimarek · commit c98ebf75efdc · 2020-03-08T09:20:01.000+11:00
diff --git a/.gitignore b/.gitignore
@@ -13,4 +13,5 @@ docs/_build/
 \.classpath
 \.project
 \.settings/
-/.nb-gradle/
+/.nb-gradle/
+gen
diff --git a/src/main/java/graphql/execution/ExecutionStepInfo.java b/src/main/java/graphql/execution/ExecutionStepInfo.java
@@ -9,7 +9,6 @@
 import graphql.schema.GraphQLTypeUtil;
 
 import java.util.Collections;
-import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.function.Consumer;
 
@@ -27,11 +26,41 @@
 @PublicApi
 public class ExecutionStepInfo {
 
+    /**
+     * An ExecutionStepInfo represent either a field or a list element inside a list of objects/interfaces/unions.
+     *
+     * A StepInfo never represent a Scalar/Enum inside a list (e.g. [String]) because GraphQL execution doesn't descend down
+     * scalar/enums lists.
+     *
+     */
+
+    /**
+     * If this StepInfo represent a field the type is equal to fieldDefinition.getType()
+     *
+     * if this StepInfo is a list element this type is the actual current list element. For example:
+     * Query.pets: [[Pet]] with Pet either a Dog or Cat and the actual result is [[Dog1],[[Cat1]]
+     * Then the type is (for a query "{pets{name}}"):
+     * [[Pet]] for /pets (representing the field Query.pets, not a list element)
+     * [Pet] fot /pets[0]
+     * [Pet] for /pets[1]
+     * Dog for /pets[0][0]
+     * Cat for /pets[1][0]
+     * String for /pets[0][0]/name (representing the field Dog.name, not a list element)
+     * String for /pets[1][0]/name (representing the field Cat.name, not a list element)
+     */
     private final GraphQLOutputType type;
+
+    /**
+     * A list element is characterized by having a path ending with an index segment. (ExecutionPath.isListSegment())
+     */
     private final ExecutionPath path;
     private final ExecutionStepInfo parent;
 
-    // field, fieldDefinition, fieldContainer and arguments stay the same for steps inside a list field
+    /**
+     * field, fieldDefinition, fieldContainer and arguments differ per field StepInfo.
+     *
+     * But for list StepInfos these properties are the same as the field returning the list.
+     */
     private final MergedField field;
     private final GraphQLFieldDefinition fieldDefinition;
     private final GraphQLObjectType fieldContainer;
diff --git a/src/test/groovy/graphql/execution/ExecutionStepInfoTest.groovy b/src/test/groovy/graphql/execution/ExecutionStepInfoTest.groovy
@@ -12,6 +12,7 @@ import graphql.schema.GraphQLNonNull
 import graphql.schema.GraphQLObjectType
 import graphql.schema.GraphQLType
 import graphql.schema.GraphQLTypeUtil
+import graphql.schema.TypeResolver
 import spock.lang.Specification
 
 import java.util.function.Function
@@ -22,6 +23,7 @@ import static graphql.TestUtil.mergedField
 import static graphql.schema.GraphQLFieldDefinition.newFieldDefinition
 import static graphql.schema.GraphQLList.list
 import static graphql.schema.GraphQLNonNull.nonNull
+import static graphql.schema.GraphQLTypeUtil.simplePrint
 import static graphql.schema.GraphQLTypeUtil.unwrapAll
 import static graphql.schema.idl.RuntimeWiring.newRuntimeWiring
 import static graphql.schema.idl.TypeRuntimeWiring.newTypeWiring
@@ -229,4 +231,87 @@ class ExecutionStepInfoTest extends Specification {
         then:
         transformed.getFieldContainer() == executionStepInfo.getFieldContainer()
     }
+
+    def "step info for list of lists of abstract type"() {
+        def spec = '''
+            type Query {
+                pets: [[Pet]]
+            }
+            
+            interface Pet {
+                names : [String]
+            }
+            type Cat implements Pet {
+                names : [String]
+            }
+            type Dog implements Pet {
+                names : [String]
+            }
+        '''
+
+        def dog = [name: "Dog", __typename: "Dog"]
+        def cat = [name: "Cat", __typename: "Cat"]
+        def petTypeResolver = { it -> it.schema.getObjectType(it.object.__typename) } as TypeResolver
+
+
+        ExecutionStepInfo dogStepInfo
+        def dogDf = { it ->
+            dogStepInfo = it.getExecutionStepInfo()
+            return null
+        } as DataFetcher
+
+
+        ExecutionStepInfo catStepInfo
+        def catDf = { it ->
+            catStepInfo = it.getExecutionStepInfo()
+            return null
+        } as DataFetcher
+
+        def pets = [[dog], [cat]]
+        def runtimeWiring = newRuntimeWiring()
+                .type(newTypeWiring("Query").dataFetcher("pets", { it -> pets }))
+                .type(newTypeWiring("Pet").typeResolver(petTypeResolver).build())
+                .type(newTypeWiring("Cat").dataFetcher("names", catDf).build())
+                .type(newTypeWiring("Dog").dataFetcher("names", dogDf).build())
+                .build()
+
+        def graphQL = TestUtil.graphQL(spec, runtimeWiring).build()
+
+        def query = ''' 
+            {
+               pets {names} 
+            }
+            '''
+        def executionInput = ExecutionInput.newExecutionInput().query(query).build()
+        when:
+        graphQL.execute(executionInput)
+        then:
+        // dog info
+        dogStepInfo.path.toString() == "/pets[0][0]/names"
+        simplePrint(dogStepInfo.type) == "[String]"
+
+        dogStepInfo.parent.path.toString() == "/pets[0][0]"
+        simplePrint(dogStepInfo.parent.type) == "Dog"
+
+        dogStepInfo.parent.parent.path.toString() == "/pets[0]"
+        simplePrint(dogStepInfo.parent.parent.type) == "[Pet]"
+
+        dogStepInfo.parent.parent.parent.path.toString() == "/pets"
+        simplePrint(dogStepInfo.parent.parent.parent.type) == "[[Pet]]"
+
+        // cat info
+        catStepInfo.path.toString() == "/pets[1][0]/names"
+        simplePrint(catStepInfo.type) == "[String]"
+
+        catStepInfo.parent.path.toString() == "/pets[1][0]"
+        simplePrint(catStepInfo.parent.type) == "Cat"
+
+        catStepInfo.parent.parent.path.toString() == "/pets[1]"
+        simplePrint(catStepInfo.parent.parent.type) == "[Pet]"
+
+        catStepInfo.parent.parent.parent.path.toString() == "/pets"
+        simplePrint(catStepInfo.parent.parent.parent.type) == "[[Pet]]"
+
+
+    }
 }
