fix schema wiring (#30)

(cherry picked from commit d70dbe6)

Author: pelletier197

src/main/java/graphql/validation/schemawiring/FieldValidatorDataFetcher.java

@@ -0,0 +1,79 @@
+package graphql.validation.schemawiring;
+
+import graphql.GraphQLError;
+import graphql.schema.*;
+import graphql.validation.interpolation.MessageInterpolator;
+import graphql.validation.rules.OnValidationErrorStrategy;
+import graphql.validation.rules.TargetedValidationRules;
+import graphql.validation.rules.ValidationRule;
+import graphql.validation.rules.ValidationRules;
+import graphql.validation.util.Util;
+
+import java.util.List;
+import java.util.Locale;
+
+public class FieldValidatorDataFetcher implements DataFetcher<Object> {
+    private final OnValidationErrorStrategy errorStrategy;
+    private final MessageInterpolator messageInterpolator;
+    private final DataFetcher<?> defaultDataFetcher;
+    private final Locale defaultLocale;
+    private final ValidationRules validationRules;
+    private TargetedValidationRules applicableRules;
+
+    public FieldValidatorDataFetcher(OnValidationErrorStrategy errorStrategy,
+                                     MessageInterpolator messageInterpolator,
+                                     DataFetcher<?> defaultDataFetcher,
+                                     Locale defaultLocale,
+                                     ValidationRules validationRules) {
+        this.errorStrategy = errorStrategy;
+        this.messageInterpolator = messageInterpolator;
+        this.defaultDataFetcher = defaultDataFetcher;
+        this.defaultLocale = defaultLocale;
+        this.validationRules = validationRules;
+        this.applicableRules = null;
+    }
+
+    @Override
+    public Object get(DataFetchingEnvironment environment) throws Exception {
+        if (!wereApplicableRulesFetched()) {
+            fetchApplicableRules(environment);
+        }
+
+        // When no validation is performed, this data fetcher is a pass-through
+        if (applicableRules.isEmpty()) {
+            return defaultDataFetcher.get(environment);
+        }
+
+        List<GraphQLError> errors = applicableRules.runValidationRules(environment, messageInterpolator, defaultLocale);
+        if (!errors.isEmpty()) {
+            if (!errorStrategy.shouldContinue(errors, environment)) {
+                return errorStrategy.onErrorValue(errors, environment);
+            }
+        }
+
+        Object returnValue = defaultDataFetcher.get(environment);
+        if (errors.isEmpty()) {
+            return returnValue;
+        }
+        return Util.mkDFRFromFetchedResult(errors, returnValue);
+    }
+
+    private void fetchApplicableRules(DataFetchingEnvironment environment) {
+        final GraphQLFieldDefinition field = environment.getFieldDefinition();
+        final GraphQLFieldsContainer container = asContainer(environment);
+
+        applicableRules = validationRules.buildRulesFor(field, container);
+    }
+
+    private GraphQLFieldsContainer asContainer(DataFetchingEnvironment environment) {
+        final GraphQLType parent = environment.getParentType();
+        if (parent == null) {
+            return null;
+        }
+        return (GraphQLFieldsContainer) environment.getParentType();
+    }
+
+    private boolean wereApplicableRulesFetched() {
+        return applicableRules != null;
+    }
+}

src/main/java/graphql/validation/schemawiring/ValidationSchemaWiring.java

@@ -1,6 +1,5 @@
 package graphql.validation.schemawiring;
 
-import graphql.GraphQLError;
 import graphql.PublicApi;
 import graphql.schema.DataFetcher;
 import graphql.schema.GraphQLFieldDefinition;
@@ -11,17 +10,15 @@
 import graphql.validation.rules.OnValidationErrorStrategy;
 import graphql.validation.rules.TargetedValidationRules;
 import graphql.validation.rules.ValidationRules;
-import graphql.validation.util.Util;
 
-import java.util.List;
 import java.util.Locale;
 
 /**
- * A {@link graphql.schema.idl.SchemaDirectiveWiring} that can be used to inject validation rules into the data fetchers
+ * A {@link SchemaDirectiveWiring} that can be used to inject validation rules into the data fetchers
  * when the graphql schema is being built.  It will use the validation rules and ask each one of they apply to the field and or its
  * arguments.
  * <p>
- * If there are rules that apply then it will it will change the {@link graphql.schema.DataFetcher} of that field so that rules get run
+ * If there are rules that apply then it will it will change the {@link DataFetcher} of that field so that rules get run
  * BEFORE the original field fetch is run.
  */
 @PublicApi
@@ -38,40 +35,29 @@ public GraphQLFieldDefinition onField(SchemaDirectiveWiringEnvironment<GraphQLFi
         GraphQLFieldsContainer fieldsContainer = env.getFieldsContainer();
         GraphQLFieldDefinition fieldDefinition = env.getFieldDefinition();
 
-        TargetedValidationRules rules = ruleCandidates.buildRulesFor(fieldDefinition, fieldsContainer);
-        if (rules.isEmpty()) {
-            return fieldDefinition; // no rules - no validation needed
-        }
-
         OnValidationErrorStrategy errorStrategy = ruleCandidates.getOnValidationErrorStrategy();
         MessageInterpolator messageInterpolator = ruleCandidates.getMessageInterpolator();
         Locale locale = ruleCandidates.getLocale();
 
-        final DataFetcher currentDF = env.getCodeRegistry().getDataFetcher(fieldsContainer, fieldDefinition);
-        final DataFetcher newDF = buildValidatingDataFetcher(rules, errorStrategy, messageInterpolator, currentDF, locale);
+        final DataFetcher<?> currentDF = env.getCodeRegistry().getDataFetcher(fieldsContainer, fieldDefinition);
+        final DataFetcher<?> newDF = buildValidatingDataFetcher(errorStrategy, messageInterpolator, currentDF, locale);
 
         env.getCodeRegistry().dataFetcher(fieldsContainer, fieldDefinition, newDF);
 
         return fieldDefinition;
     }
 
-    private DataFetcher buildValidatingDataFetcher(TargetedValidationRules rules, OnValidationErrorStrategy errorStrategy, MessageInterpolator messageInterpolator, DataFetcher currentDF, final Locale defaultLocale) {
-        // ok we have some rules that need to be applied to this field and its arguments
-        return environment -> {
-            List<GraphQLError> errors = rules.runValidationRules(environment, messageInterpolator, defaultLocale);
-            if (!errors.isEmpty()) {
-                // should we continue?
-                if (!errorStrategy.shouldContinue(errors, environment)) {
-                    return errorStrategy.onErrorValue(errors, environment);
-                }
-            }
-            // we have no validation errors or they said continue so call the underlying data fetcher
-            Object returnValue = currentDF.get(environment);
-            if (errors.isEmpty()) {
-                return returnValue;
-            }
-            return Util.mkDFRFromFetchedResult(errors, returnValue);
-        };
+    private DataFetcher<Object> buildValidatingDataFetcher(OnValidationErrorStrategy errorStrategy,
+                                                           MessageInterpolator messageInterpolator,
+                                                           DataFetcher<?> currentDF,
+                                                           final Locale defaultLocale) {
+        return new FieldValidatorDataFetcher(
+                errorStrategy,
+                messageInterpolator,
+                currentDF,
+                defaultLocale,
+                ruleCandidates
+        );
     }
 
 }