Use a modified copy of the CollectFields algorithm

graphql · May 26, 2021 · 0308b27 · 0308b27
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diff --git a/spec/Section 5 -- Validation.md b/spec/Section 5 -- Validation.md
@@ -253,17 +253,65 @@ query getName {
   * Let {subscriptionType} be the root Subscription type in {schema}.
   * Let {selectionSet} be the top level selection set on {subscription}.
   * Let {groupedFieldSet} be the result of
-    {CollectFields(subscriptionType, selectionSet, null)}.
+    {CollectSubscriptionFields(subscriptionType, selectionSet)}.
   * {groupedFieldSet} must have exactly one entry, which must not be an
     introspection field.
 
+CollectSubscriptionFields(objectType, selectionSet, visitedFragments):
+
+  * If {visitedFragments} is not provided, initialize it to the empty set.
+  * Initialize {groupedFields} to an empty ordered map of lists.
+  * For each {selection} in {selectionSet}:
+    * {selection} must not provide the `@skip` directive.
+    * {selection} must not provide the `@include` directive.
+    * If {selection} is a {Field}:
+      * Let {responseKey} be the response key of {selection} (the alias if defined, otherwise the field name).
+      * Let {groupForResponseKey} be the list in {groupedFields} for
+        {responseKey}; if no such list exists, create it as an empty list.
+      * Append {selection} to the {groupForResponseKey}.
+    * If {selection} is a {FragmentSpread}:
+      * Let {fragmentSpreadName} be the name of {selection}.
+      * If {fragmentSpreadName} is in {visitedFragments}, continue with the
+        next {selection} in {selectionSet}.
+      * Add {fragmentSpreadName} to {visitedFragments}.
+      * Let {fragment} be the Fragment in the current Document whose name is
+        {fragmentSpreadName}.
+      * If no such {fragment} exists, continue with the next {selection} in
+        {selectionSet}.
+      * Let {fragmentType} be the type condition on {fragment}.
+      * If {DoesFragmentTypeApply(objectType, fragmentType)} is false, continue
+        with the next {selection} in {selectionSet}.
+      * Let {fragmentSelectionSet} be the top-level selection set of {fragment}.
+      * Let {fragmentGroupedFieldSet} be the result of calling
+        {CollectSubscriptionFields(objectType, fragmentSelectionSet, visitedFragments)}.
+      * For each {fragmentGroup} in {fragmentGroupedFieldSet}:
+        * Let {responseKey} be the response key shared by all fields in {fragmentGroup}.
+        * Let {groupForResponseKey} be the list in {groupedFields} for
+          {responseKey}; if no such list exists, create it as an empty list.
+        * Append all items in {fragmentGroup} to {groupForResponseKey}.
+    * If {selection} is an {InlineFragment}:
+      * Let {fragmentType} be the type condition on {selection}.
+      * If {fragmentType} is not {null} and {DoesFragmentTypeApply(objectType, fragmentType)} is false, continue
+        with the next {selection} in {selectionSet}.
+      * Let {fragmentSelectionSet} be the top-level selection set of {selection}.
+      * Let {fragmentGroupedFieldSet} be the result of calling {CollectSubscriptionFields(objectType, fragmentSelectionSet, visitedFragments)}.
+      * For each {fragmentGroup} in {fragmentGroupedFieldSet}:
+        * Let {responseKey} be the response key shared by all fields in {fragmentGroup}.
+        * Let {groupForResponseKey} be the list in {groupedFields} for
+          {responseKey}; if no such list exists, create it as an empty list.
+        * Append all items in {fragmentGroup} to {groupForResponseKey}.
+  * Return {groupedFields}.
+
+Note: This algorithm is very similar to {CollectFields()}, it differs in that
+it does not have access to runtime variables and thus the `@skip` and
+`@include` directives cannot be used.
+
 **Explanatory Text**
 
 Subscription operations must have exactly one root field.
 
 To enable us to determine this without access to runtime variables, we must
-forbid the `@skip` and `@include` directives in the root selection set (by
-passing `null` as the `variableValues` argument to {CollectFields()}).
+forbid the `@skip` and `@include` directives in the root selection set.
 
 Valid examples:
 

diff --git a/spec/Section 6 -- Execution.md b/spec/Section 6 -- Execution.md
@@ -479,28 +479,17 @@ The depth-first-search order of the field groups produced by {CollectFields()}
 is maintained through execution, ensuring that fields appear in the executed
 response in a stable and predictable order.
 
-When {CollectFields()} is used during validation (see for example the
-[single root field](#sec-Single-root-field) subscription operation validation
-rule), the runtime value for {variableValues} will not be available - in this
-case we set {variableValues} to {null} and forbid the use of the `@skip` and
-`@include` directives. During execution, {variableValues} will always be
-non-null.
-
 CollectFields(objectType, selectionSet, variableValues, visitedFragments):
 
   * If {visitedFragments} is not provided, initialize it to the empty set.
   * Initialize {groupedFields} to an empty ordered map of lists.
   * For each {selection} in {selectionSet}:
-    * If {variableValues} is {null}:
-      * {selection} must not provide the `@skip` directive.
-      * {selection} must not provide the `@include` directive.
-    * Otherwise:
-      * If {selection} provides the directive `@skip`, let {skipDirective} be that directive.
-        * If {skipDirective}'s {if} argument is {true} or is a variable in {variableValues} with the value {true}, continue with the next
-        {selection} in {selectionSet}.
-      * If {selection} provides the directive `@include`, let {includeDirective} be that directive.
-        * If {includeDirective}'s {if} argument is not {true} and is not a variable in {variableValues} with the value {true}, continue with the next
-        {selection} in {selectionSet}.
+    * If {selection} provides the directive `@skip`, let {skipDirective} be that directive.
+      * If {skipDirective}'s {if} argument is {true} or is a variable in {variableValues} with the value {true}, continue with the next
+      {selection} in {selectionSet}.
+    * If {selection} provides the directive `@include`, let {includeDirective} be that directive.
+      * If {includeDirective}'s {if} argument is not {true} and is not a variable in {variableValues} with the value {true}, continue with the next
+      {selection} in {selectionSet}.
     * If {selection} is a {Field}:
       * Let {responseKey} be the response key of {selection} (the alias if defined, otherwise the field name).
       * Let {groupForResponseKey} be the list in {groupedFields} for