Fix/planning interfaces with entity implementations

v2/pkg/ast/ast_field.go

@@ -128,3 +128,10 @@ func (d *Document) FieldsAreEqualFlat(left, right int) bool {
 		d.ArgumentSetsAreEquals(d.FieldArguments(left), d.FieldArguments(right)) && // arguments
 		d.DirectiveSetsAreEqual(d.FieldDirectives(left), d.FieldDirectives(right)) // directives
 }
+
+func (d *Document) FieldSelectionSet(ref int) (selectionSetRef int, ok bool) {
+	if !d.Fields[ref].HasSelections {
+		return InvalidRef, false
+	}
+	return d.Fields[ref].SelectionSet, true
+}

v2/pkg/ast/ast_field_definition.go

@@ -140,6 +140,10 @@ func (d *Document) FieldDefinitionTypeNameString(ref int) string {
 	return d.ResolveTypeNameString(d.FieldDefinitions[ref].Type)
 }
 
+func (d *Document) FieldDefinitionTypeNameBytes(ref int) ByteSlice {
+	return d.ResolveTypeNameBytes(d.FieldDefinitions[ref].Type)
+}
+
 func (d *Document) FieldDefinitionTypeNode(ref int) Node {
 	typeName := d.ResolveTypeNameBytes(d.FieldDefinitions[ref].Type)
 	node, _ := d.Index.FirstNodeByNameBytes(typeName)

v2/pkg/ast/ast_inline_fragment.go

@@ -75,3 +75,10 @@ func (d *Document) AddInlineFragment(fragment InlineFragment) int {
 func (d *Document) InlineFragmentIsOfTheSameType(ref int) bool {
 	return d.InlineFragments[ref].IsOfTheSameType
 }
+
+func (d *Document) InlineFragmentSelectionSet(ref int) (selectionSetRef int, ok bool) {
+	if !d.InlineFragments[ref].HasSelections {
+		return InvalidRef, false
+	}
+	return d.InlineFragments[ref].SelectionSet, true
+}

v2/pkg/ast/ast_selection.go

@@ -139,6 +139,10 @@ func (d *Document) AddSelection(set int, selection Selection) {
 	d.SelectionSets[set].SelectionRefs = append(d.SelectionSets[set].SelectionRefs, d.AddSelectionToDocument(selection))
 }
 
+func (d *Document) AddSelectionRefToSelectionSet(set int, selectionRef int) {
+	d.SelectionSets[set].SelectionRefs = append(d.SelectionSets[set].SelectionRefs, selectionRef)
+}
+
 func (d *Document) EmptySelectionSet(ref int) {
 	d.SelectionSets[ref].SelectionRefs = d.SelectionSets[ref].SelectionRefs[:0]
 }
@@ -202,3 +206,34 @@ func (d *Document) SelectionSetHasFieldSelectionWithExactName(set int, name []by
 	}
 	return false, InvalidRef
 }
+
+func (d *Document) SelectionSetFieldSelections(set int) (refs []int) {
+	for _, selectionRef := range d.SelectionSets[set].SelectionRefs {
+		if d.Selections[selectionRef].Kind == SelectionKindField {
+			refs = append(refs, selectionRef)
+		}
+	}
+	return
+}
+
+func (d *Document) SelectionSetInlineFragmentSelections(set int) (refs []int) {
+	for _, selectionRef := range d.SelectionSets[set].SelectionRefs {
+		if d.Selections[selectionRef].Kind == SelectionKindInlineFragment {
+			refs = append(refs, selectionRef)
+		}
+	}
+	return
+}
+
+func (d *Document) SelectionKind(ref int) SelectionKind {
+	return d.Selections[ref].Kind
+}
+
+func (d *Document) SelectionSetFieldNames(set int) (fieldNames []string) {
+	fieldSelections := d.SelectionSetFieldSelections(set)
+	fieldNames = make([]string, 0, len(fieldSelections))
+	for _, fieldSelectionRef := range fieldSelections {
+		fieldNames = append(fieldNames, d.FieldNameString(d.Selections[fieldSelectionRef].Ref))
+	}
+	return
+}

v2/pkg/engine/datasource/graphql_datasource/graphql_datasource.go

@@ -317,7 +317,7 @@ func (p *Planner) Register(visitor *plan.Visitor, configuration plan.DataSourceC
 	return nil
 }
 
-func (p *Planner) ConfigureFetch() plan.FetchConfiguration {
+func (p *Planner) ConfigureFetch() resolve.FetchConfiguration {
 	var input []byte
 	input = httpclient.SetInputBodyWithPath(input, p.upstreamVariables, "variables")
 	input = httpclient.SetInputBodyWithPath(input, p.printOperation(), "query")
@@ -343,15 +343,16 @@ func (p *Planner) ConfigureFetch() plan.FetchConfiguration {
 		}
 	}
 
-	return plan.FetchConfiguration{
+	return resolve.FetchConfiguration{
 		Input: string(input),
 		DataSource: &Source{
 			httpClient: p.fetchClient,
 		},
 		Variables:                             p.variables,
 		DisallowSingleFlight:                  p.disallowSingleFlight,
 		RequiresSerialFetch:                   p.requiresSerialFetch(),
-		RequiresBatchFetch:                    p.requiresBatchFetch(),
+		RequiresEntityFetch:                   p.requiresEntityFetch(),
+		RequiresEntityBatchFetch:              p.requiresEntityBatchFetch(),
 		PostProcessing:                        postProcessing,
 		SetTemplateOutputToNullOnVariableNull: p.extractEntities,
 	}
@@ -377,12 +378,12 @@ func (p *Planner) requiresSerialFetch() bool {
 	return false
 }
 
-func (p *Planner) requiresBatchFetch() bool {
-	if !p.dataSourcePlannerConfig.HasRequiredFields() {
-		return false
-	}
+func (p *Planner) requiresEntityFetch() bool {
+	return p.dataSourcePlannerConfig.HasRequiredFields() && p.dataSourcePlannerConfig.PathType == plan.PlannerPathObject
+}
 
-	return p.dataSourcePlannerConfig.PathType != plan.PlannerPathObject
+func (p *Planner) requiresEntityBatchFetch() bool {
+	return p.dataSourcePlannerConfig.HasRequiredFields() && p.dataSourcePlannerConfig.PathType != plan.PlannerPathObject
 }
 
 func (p *Planner) ConfigureSubscription() plan.SubscriptionConfiguration {
@@ -749,16 +750,9 @@ func (p *Planner) addRepresentationsVariable() {
 }
 
 func (p *Planner) buildRepresentationsVariable() resolve.Variable {
-	isArrayItems := p.dataSourcePlannerConfig.PathType != plan.PlannerPathObject
-
-	uniqTypes := p.dataSourcePlannerConfig.RequiredFields.UniqueTypes()
-	if len(uniqTypes) > 1 && !isArrayItems {
-		p.stopWithError("unhandled case: more than one type requirements for non-array path type")
-	}
-
 	objects := make([]*resolve.Object, 0, len(p.dataSourcePlannerConfig.RequiredFields))
 	for _, cfg := range p.dataSourcePlannerConfig.RequiredFields {
-		node, err := buildRepresentationVariableNode(cfg, p.visitor.Definition, false, isArrayItems)
+		node, err := buildRepresentationVariableNode(cfg, p.visitor.Definition)
 		if err != nil {
 			p.visitor.Walker.StopWithInternalErr(err)
 			return nil