Scalar type for UUID

Author: Ravi Kancherla

readme.md

@@ -73,6 +73,11 @@ And example query might look like:
     }
 
 ``` 
+## ID Scalars
+
+* `UUID`
+    * A universally unique identifier scalar that accepts uuid values like `2423f0a0-3b81-4115-a189-18df8b35e8fc` and produces
+    `java.util.UUID` type at runtime
 
 ## Object / JSON Scalars
 

src/main/java/graphql/scalars/ExtendedScalars.java

@@ -5,6 +5,7 @@
 import graphql.scalars.datetime.DateScalar;
 import graphql.scalars.datetime.DateTimeScalar;
 import graphql.scalars.datetime.TimeScalar;
+import graphql.scalars.id.UUIDScalar;
 import graphql.scalars.numeric.NegativeFloatScalar;
 import graphql.scalars.numeric.NegativeIntScalar;
 import graphql.scalars.numeric.NonNegativeFloatScalar;
@@ -20,6 +21,8 @@
 import graphql.scalars.locale.LocaleScalar;
 import graphql.schema.GraphQLScalarType;
 
+import java.util.UUID;
+
 /**
  * This is the API entry point for all the extended scalars
  */
@@ -118,6 +121,12 @@ public class ExtendedScalars {
      */
     public static GraphQLScalarType Locale = new LocaleScalar();
 
+    /**
+     * A UUID scalar that accepts a universally unique identifier and produces {@link
+     * java.util.UUID} objects at runtime.
+     */
+    public static GraphQLScalarType UUID = new UUIDScalar();
+
     /**
      * An `Int` scalar that MUST be greater than zero
      *

src/main/java/graphql/scalars/id/UUIDScalar.java

@@ -0,0 +1,87 @@
+package graphql.scalars.id;
+
+import graphql.Internal;
+import graphql.language.StringValue;
+import graphql.schema.Coercing;
+import graphql.schema.CoercingParseLiteralException;
+import graphql.schema.CoercingParseValueException;
+import graphql.schema.CoercingSerializeException;
+import graphql.schema.GraphQLScalarType;
+
+import java.time.DateTimeException;
+import java.time.format.DateTimeFormatter;
+import java.util.UUID;
+
+import static graphql.scalars.util.Kit.typeName;
+
+/**
+ * Access this via {@link graphql.scalars.ExtendedScalars#UUID}
+ */
+@Internal
+public class UUIDScalar extends GraphQLScalarType {
+
+  public UUIDScalar() {
+    super("UUID", "A universally unique identifier compliant UUID Scalar", new Coercing<UUID, String>() {
+      @Override
+      public String serialize(Object input) throws CoercingSerializeException {
+        if (input instanceof String) {
+          try {
+            return (UUID.fromString((String)input)).toString();
+          } catch ( IllegalArgumentException ex) {
+            throw new CoercingSerializeException(
+              "Expected a UUID value that can be converted : '" + ex.getMessage() + "'."
+            );
+          }
+        }
+        else if(input instanceof UUID) {
+          return input.toString();
+        }
+        else {
+          throw new CoercingSerializeException(
+            "Expected something we can convert to 'java.util.UUID' but was '" + typeName(input) + "'."
+          );
+        }
+      }
+
+      @Override
+      public UUID parseValue(Object input) throws CoercingParseValueException {
+        if(input instanceof String) {
+          try {
+            return UUID.fromString((String) input);
+          } catch (IllegalArgumentException ex) {
+            throw new CoercingParseValueException(
+              "Expected a 'String' of UUID type but was '" + typeName(input) + "'."
+            );
+          }
+        }
+        else if(input instanceof UUID) {
+          return (UUID) input;
+        }
+        else {
+          throw new CoercingParseValueException(
+            "Expected a 'String' or 'UUID' type but was '" + typeName(input) + "'."
+          );
+        }
+      }
+
+      @Override
+      public UUID parseLiteral(Object input) throws CoercingParseLiteralException {
+        if (!(input instanceof StringValue)) {
+          throw new CoercingParseLiteralException(
+            "Expected a 'java.util.UUID' AST type object but was '" + typeName(input) + "'."
+          );
+        }
+        try {
+          return UUID.fromString(((StringValue) input).getValue());
+        } catch (IllegalArgumentException ex) {
+          throw new CoercingParseLiteralException(
+            "Expected something that we can convert to a UUID but was invalid"
+          );
+        }
+
+      }
+
+    });
+  }
+
+}

src/test/groovy/graphql/scalars/id/UUIDScalarTest.groovy

@@ -0,0 +1,90 @@
+package graphql.scalars.id
+
+import graphql.language.StringValue
+import graphql.schema.CoercingParseLiteralException
+import graphql.schema.CoercingParseValueException
+import graphql.schema.CoercingSerializeException
+import spock.lang.Specification
+import spock.lang.Unroll
+
+import static graphql.scalars.util.TestKit.*
+
+class UUIDScalarTest extends Specification {
+
+    def coercing = new UUIDScalar().getCoercing()
+
+    @Unroll
+    def "UUID parseValue"() {
+
+        when:
+        def result = coercing.parseValue(input)
+        then:
+        result == expectedValue
+        where:
+        input                                       | expectedValue
+        "43f20307-603c-4ad1-83c6-6010d224fabf"      | mkUUIDValue("43f20307-603c-4ad1-83c6-6010d224fabf")
+        "787dbc2b-3ddb-4098-ad1d-63d026bac111"      | mkUUIDValue("787dbc2b-3ddb-4098-ad1d-63d026bac111")
+    }
+
+    @Unroll
+    def "UUID parseValue bad inputs"() {
+
+        when:
+        coercing.parseValue(input)
+        then:
+        thrown(expectedValue)
+        where:
+        input                               | expectedValue
+        "a-string-that-is-not-uuid"         | CoercingParseValueException
+        100                                 | CoercingParseValueException
+        "1985-04-12"                        | CoercingParseValueException
+    }
+
+    def "UUID AST literal"() {
+
+        when:
+        def result = coercing.parseLiteral(input)
+        then:
+        result == expectedValue
+        where:
+        input                                                   | expectedValue
+        new StringValue("6972117d-3963-4214-ab2c-fa973d7e996b") | mkUUIDValue("6972117d-3963-4214-ab2c-fa973d7e996b")
+    }
+
+    def "UUID AST literal bad inputs"() {
+
+        when:
+        coercing.parseLiteral(input)
+        then:
+        thrown(expectedValue)
+        where:
+        input                                                   | expectedValue
+        new StringValue("a-string-that-us-not-uuid")            | CoercingParseLiteralException
+    }
+
+    def "UUID serialization"() {
+
+        when:
+        def result = coercing.serialize(input)
+        then:
+        result == expectedValue
+        where:
+        input                                                   | expectedValue
+        "42287d47-c5bd-45e4-b470-53e426d3d503"                  | "42287d47-c5bd-45e4-b470-53e426d3d503"
+        "423df0f3-cf05-4eb5-b708-ae2f4b4a052d"                  | "423df0f3-cf05-4eb5-b708-ae2f4b4a052d"
+        mkUUIDValue("6a90b1e6-20f3-43e5-a7ba-34db8010c071")     | "6a90b1e6-20f3-43e5-a7ba-34db8010c071"
+    }
+
+    def "UUID serialization bad inputs"() {
+
+        when:
+        coercing.serialize(input)
+        then:
+        thrown(expectedValue)
+        where:
+        input                                       | expectedValue
+        "1985-04-12"                                | CoercingSerializeException
+        100                                         | CoercingSerializeException
+    }
+
+}

src/test/groovy/graphql/scalars/util/TestKit.groovy

@@ -75,4 +75,8 @@ class TestKit {
         return new FloatValue(new BigDecimal(d))
     }
 
+    static UUID mkUUIDValue(String s) {
+        return UUID.fromString(s)
+    }
+
 }