I18n for validation error messages

src/main/java/graphql/ExecutionInput.java

@@ -225,7 +225,7 @@ public static class Builder {
         //
         private DataLoaderRegistry dataLoaderRegistry = DataLoaderDispatcherInstrumentationState.EMPTY_DATALOADER_REGISTRY;
         private CacheControl cacheControl = CacheControl.newCacheControl();
-        private Locale locale;
+        private Locale locale = Locale.getDefault();
         private ExecutionId executionId;
 
         public Builder query(String query) {

src/main/java/graphql/GraphQL.java

@@ -623,7 +623,7 @@ private List<ValidationError> validate(ExecutionInput executionInput, Document d
         validationCtx.onDispatched(cf);
 
         Predicate<Class<?>> validationRulePredicate = executionInput.getGraphQLContext().getOrDefault(ParseAndValidate.INTERNAL_VALIDATION_PREDICATE_HINT, r -> true);
-        List<ValidationError> validationErrors = ParseAndValidate.validate(graphQLSchema, document, validationRulePredicate);
+        List<ValidationError> validationErrors = ParseAndValidate.validate(graphQLSchema, document, validationRulePredicate, executionInput.getLocale());
 
         validationCtx.onCompleted(validationErrors, null);
         cf.complete(validationErrors);

src/main/java/graphql/ParseAndValidate.java

@@ -9,6 +9,7 @@
 import graphql.validation.Validator;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.function.Predicate;
 
 /**
@@ -40,7 +41,7 @@ public class ParseAndValidate {
     public static ParseAndValidateResult parseAndValidate(GraphQLSchema graphQLSchema, ExecutionInput executionInput) {
         ParseAndValidateResult result = parse(executionInput);
         if (!result.isFailure()) {
-            List<ValidationError> errors = validate(graphQLSchema, result.getDocument());
+            List<ValidationError> errors = validate(graphQLSchema, result.getDocument(), executionInput.getLocale());
             return result.transform(builder -> builder.validationErrors(errors));
         }
         return result;
@@ -71,11 +72,24 @@ public static ParseAndValidateResult parse(ExecutionInput executionInput) {
      *
      * @param graphQLSchema  the graphql schema to validate against
      * @param parsedDocument the previously parsed document
+     * @param locale         the current locale
+     *
+     * @return a result object that indicates how this operation went
+     */
+    public static List<ValidationError> validate(GraphQLSchema graphQLSchema, Document parsedDocument, Locale locale) {
+        return validate(graphQLSchema, parsedDocument, ruleClass -> true, locale);
+    }
+
+    /**
+     * This can be called to validate a parsed graphql query, with the JVM default locale.
+     *
+     * @param graphQLSchema  the graphql schema to validate against
+     * @param parsedDocument the previously parsed document
      *
      * @return a result object that indicates how this operation went
      */
     public static List<ValidationError> validate(GraphQLSchema graphQLSchema, Document parsedDocument) {
-        return validate(graphQLSchema, parsedDocument, ruleClass -> true);
+        return validate(graphQLSchema, parsedDocument, ruleClass -> true, Locale.getDefault());
     }
 
     /**
@@ -84,11 +98,26 @@ public static List<ValidationError> validate(GraphQLSchema graphQLSchema, Docume
      * @param graphQLSchema  the graphql schema to validate against
      * @param parsedDocument the previously parsed document
      * @param rulePredicate  this predicate is used to decide what validation rules will be applied
+     * @param locale         the current locale
+     *
+     * @return a result object that indicates how this operation went
+     */
+    public static List<ValidationError> validate(GraphQLSchema graphQLSchema, Document parsedDocument, Predicate<Class<?>> rulePredicate, Locale locale) {
+        Validator validator = new Validator();
+        return validator.validateDocument(graphQLSchema, parsedDocument, rulePredicate, locale);
+    }
+
+    /**
+     * This can be called to validate a parsed graphql query, with the JVM default locale.
+     *
+     * @param graphQLSchema  the graphql schema to validate against
+     * @param parsedDocument the previously parsed document
+     * @param rulePredicate  this predicate is used to decide what validation rules will be applied
      *
      * @return a result object that indicates how this operation went
      */
     public static List<ValidationError> validate(GraphQLSchema graphQLSchema, Document parsedDocument, Predicate<Class<?>> rulePredicate) {
         Validator validator = new Validator();
-        return validator.validateDocument(graphQLSchema, parsedDocument, rulePredicate);
+        return validator.validateDocument(graphQLSchema, parsedDocument, rulePredicate, Locale.getDefault());
     }
 }

src/main/java/graphql/i18n/I18n.java

@@ -0,0 +1,70 @@
+package graphql.i18n;
+
+import graphql.Internal;
+import graphql.VisibleForTesting;
+
+import java.text.MessageFormat;
+import java.util.Locale;
+import java.util.MissingResourceException;
+import java.util.ResourceBundle;
+
+import static graphql.Assert.assertNotNull;
+import static graphql.Assert.assertShouldNeverHappen;
+
+@Internal
+public class I18n {
+
+    /**
+     * This enum is a type safe way to control what resource bundle to load from
+     */
+    public enum BundleType {
+        Validation,
+        Execution,
+        General;
+
+        private final String baseName;
+
+        BundleType() {
+            this.baseName = "i18n." + this.name();
+        }
+    }
+
+    private final ResourceBundle resourceBundle;
+
+    @VisibleForTesting
+    protected I18n(BundleType bundleType, Locale locale) {
+        assertNotNull(bundleType);
+        assertNotNull(locale);
+        this.resourceBundle = ResourceBundle.getBundle(bundleType.baseName, locale);
+    }
+
+    public ResourceBundle getResourceBundle() {
+        return resourceBundle;
+    }
+
+    public static I18n i18n(BundleType bundleType, Locale locale) {
+        return new I18n(bundleType, locale);
+    }
+
+
+    /**
+     * Creates an I18N message using the key and arguments
+     *
+     * @param msgKey  the key in the underlying message bundle
+     * @param msgArgs the message arguments
+     *
+     * @return the formatted I18N message
+     */
+    @SuppressWarnings("UnnecessaryLocalVariable")
+    public String msg(String msgKey, Object... msgArgs) {
+        String msgPattern = null;
+        try {
+            msgPattern = resourceBundle.getString(msgKey);
+        } catch (MissingResourceException e) {
+            assertShouldNeverHappen("There must be a resource bundle key called %s", msgKey);
+        }
+
+        String formattedMsg = new MessageFormat(msgPattern).format(msgArgs);
+        return formattedMsg;
+    }
+}

src/main/java/graphql/i18n/I18nMsg.java

@@ -0,0 +1,42 @@
+package graphql.i18n;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static java.util.Arrays.asList;
+
+/**
+ * A class that represents the intention to create a I18n message
+ */
+public class I18nMsg {
+    private final String msgKey;
+    private final List<Object> msgArguments;
+
+    public I18nMsg(String msgKey, List<Object> msgArguments) {
+        this.msgKey = msgKey;
+        this.msgArguments = msgArguments;
+    }
+
+    public I18nMsg(String msgKey, Object... msgArguments) {
+        this.msgKey = msgKey;
+        this.msgArguments = asList(msgArguments);
+    }
+
+    public String getMsgKey() {
+        return msgKey;
+    }
+
+    public Object[] getMsgArguments() {
+        return msgArguments.toArray();
+    }
+
+    public I18nMsg addArgumentAt(int index, Object argument) {
+        List<Object> newArgs = new ArrayList<>(this.msgArguments);
+        newArgs.add(index, argument);
+        return new I18nMsg(this.msgKey, newArgs);
+    }
+
+    public String toI18n(I18n i18n) {
+        return i18n.msg(msgKey, msgArguments);
+    }
+}

src/main/java/graphql/nextgen/GraphQL.java

@@ -265,7 +265,7 @@ private List<ValidationError> validate(ExecutionInput executionInput, Document d
         validationCtx.onDispatched(cf);
 
         Predicate<Class<?>> validationRulePredicate = executionInput.getGraphQLContext().getOrDefault(ParseAndValidate.INTERNAL_VALIDATION_PREDICATE_HINT, r -> true);
-        List<ValidationError> validationErrors = ParseAndValidate.validate(graphQLSchema, document, validationRulePredicate);
+        List<ValidationError> validationErrors = ParseAndValidate.validate(graphQLSchema, document, validationRulePredicate, executionInput.getLocale());
 
         validationCtx.onCompleted(validationErrors, null);
         cf.complete(validationErrors);

src/main/java/graphql/validation/AbstractRule.java

@@ -2,6 +2,7 @@
 
 
 import graphql.Internal;
+import graphql.i18n.I18nMsg;
 import graphql.language.Argument;
 import graphql.language.Directive;
 import graphql.language.Document;
@@ -22,21 +23,20 @@
 import java.util.List;
 
 import static graphql.validation.ValidationError.newValidationError;
+import static java.lang.System.arraycopy;
 
 @Internal
 public class AbstractRule {
 
     private final ValidationContext validationContext;
     private final ValidationErrorCollector validationErrorCollector;
-
-
+    private final ValidationUtil validationUtil;
     private boolean visitFragmentSpreads;
 
-    private ValidationUtil validationUtil = new ValidationUtil();
-
     public AbstractRule(ValidationContext validationContext, ValidationErrorCollector validationErrorCollector) {
         this.validationContext = validationContext;
         this.validationErrorCollector = validationErrorCollector;
+        this.validationUtil = new ValidationUtil();
     }
 
     public boolean isVisitFragmentSpreads() {
@@ -47,7 +47,6 @@ public void setVisitFragmentSpreads(boolean visitFragmentSpreads) {
         this.visitFragmentSpreads = visitFragmentSpreads;
     }
 
-
     public ValidationUtil getValidationUtil() {
         return validationUtil;
     }
@@ -78,7 +77,6 @@ public List<ValidationError> getErrors() {
         return validationErrorCollector.getErrors();
     }
 
-
     public ValidationContext getValidationContext() {
         return validationContext;
     }
@@ -91,6 +89,45 @@ protected List<String> getQueryPath() {
         return validationContext.getQueryPath();
     }
 
+    /**
+     * Creates an I18n message using the {@link graphql.i18n.I18nMsg}
+     *
+     * @param validationErrorType the type of validation failure
+     * @param i18nMsg             the i18n message object
+     *
+     * @return the formatted I18n message
+     */
+    public String i18n(ValidationErrorType validationErrorType, I18nMsg i18nMsg) {
+        return i18n(validationErrorType, i18nMsg.getMsgKey(), i18nMsg.getMsgArguments());
+    }
+
+    /**
+     * Creates an I18N message using the key and arguments
+     *
+     * @param validationErrorType the type of validation failure
+     * @param msgKey              the key in the underlying message bundle
+     * @param msgArgs             the message arguments
+     *
+     * @return the formatted I18N message
+     */
+    public String i18n(ValidationErrorType validationErrorType, String msgKey, Object... msgArgs) {
+        Object[] params = new Object[msgArgs.length + 1];
+        params[0] = mkTypeAndPath(validationErrorType);
+        arraycopy(msgArgs, 0, params, 1, msgArgs.length);
+
+        return validationContext.i18n(msgKey, params);
+    }
+
+    private String mkTypeAndPath(ValidationErrorType validationErrorType) {
+        List<String> queryPath = getQueryPath();
+        StringBuilder sb = new StringBuilder();
+        sb.append(validationErrorType);
+        if (queryPath != null) {
+            sb.append("@[").append(String.join("/", queryPath)).append("]");
+        }
+        return sb.toString();
+    }
+
     public void checkDocument(Document document) {
 
     }

src/main/java/graphql/validation/ArgumentValidationUtil.java

@@ -2,6 +2,7 @@
 
 import graphql.GraphQLError;
 import graphql.Internal;
+import graphql.i18n.I18nMsg;
 import graphql.language.Argument;
 import graphql.language.ObjectField;
 import graphql.language.Value;
@@ -20,7 +21,7 @@ public class ArgumentValidationUtil extends ValidationUtil {
 
     private final List<String> argumentNames = new ArrayList<>();
     private Value<?> argumentValue;
-    private String errorMessage;
+    private String errMsgKey;
     private final List<Object> arguments = new ArrayList<>();
     private Map<String, Object> errorExtensions;
 
@@ -33,13 +34,17 @@ public ArgumentValidationUtil(Argument argument) {
 
     @Override
     protected void handleNullError(Value<?> value, GraphQLType type) {
-        errorMessage = "must not be null";
+        errMsgKey = "ArgumentValidationUtil.handleNullError";
         argumentValue = value;
     }
 
     @Override
     protected void handleScalarError(Value<?> value, GraphQLScalarType type, GraphQLError invalid) {
-        errorMessage = "is not a valid '%s' - %s";
+        if (invalid.getMessage() == null) {
+            errMsgKey = "ArgumentValidationUtil.handleScalarError";
+        } else {
+            errMsgKey = "ArgumentValidationUtil.handleScalarErrorCustomMessage";
+        }
         arguments.add(type.getName());
         arguments.add(invalid.getMessage());
         argumentValue = value;
@@ -48,26 +53,30 @@ protected void handleScalarError(Value<?> value, GraphQLScalarType type, GraphQL
 
     @Override
     protected void handleEnumError(Value<?> value, GraphQLEnumType type, GraphQLError invalid) {
-        errorMessage = "is not a valid '%s' - %s";
+        if (invalid.getMessage() == null) {
+            errMsgKey = "ArgumentValidationUtil.handleEnumError";
+        } else {
+            errMsgKey = "ArgumentValidationUtil.handleEnumErrorCustomMessage";
+        }
         arguments.add(type.getName());
         arguments.add(invalid.getMessage());
         argumentValue = value;
     }
 
     @Override
     protected void handleNotObjectError(Value<?> value, GraphQLInputObjectType type) {
-        errorMessage = "must be an object type";
+        errMsgKey = "ArgumentValidationUtil.handleNotObjectError";
     }
 
     @Override
     protected void handleMissingFieldsError(Value<?> value, GraphQLInputObjectType type, Set<String> missingFields) {
-        errorMessage = "is missing required fields '%s'";
+        errMsgKey = "ArgumentValidationUtil.handleMissingFieldsError";
         arguments.add(missingFields);
     }
 
     @Override
     protected void handleExtraFieldError(Value<?> value, GraphQLInputObjectType type, ObjectField objectField) {
-        errorMessage = "contains a field not in '%s': '%s'";
+        errMsgKey = "ArgumentValidationUtil.handleExtraFieldError";
         arguments.add(type.getName());
         arguments.add(objectField.getName());
     }
@@ -82,7 +91,7 @@ protected void handleFieldNotValidError(Value<?> value, GraphQLType type, int in
         argumentNames.add(0, String.format("[%s]", index));
     }
 
-    public String getMessage() {
+    public I18nMsg getMsgAndArgs() {
         StringBuilder argument = new StringBuilder(argumentName);
         for (String name : argumentNames) {
             if (name.startsWith("[")) {
@@ -94,9 +103,7 @@ public String getMessage() {
         arguments.add(0, argument.toString());
         arguments.add(1, argumentValue);
 
-        String message = "argument '%s' with value '%s'" + " " + errorMessage;
-
-        return String.format(message, arguments.toArray());
+        return new I18nMsg(errMsgKey, arguments);
     }
 
     public Map<String, Object> getErrorExtensions() {