feat: allow non backward compatible required member

smithy-typescript-codegen-test/smithy-build.json

@@ -8,7 +8,8 @@
             "packageVersion": "0.0.1",
             "packageJson": {
                 "license": "Apache-2.0"
-            }
+            },
+            "memberNullabilityCompatibilityMode": "strict"
         }
     }
 }

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/DirectedTypeScriptCodegen.java

@@ -328,7 +328,8 @@ public void generateStructure(GenerateStructureDirective<TypeScriptCodegenContex
                     directive.symbolProvider(),
                     writer,
                     directive.shape(),
-                    directive.settings().generateServerSdk()
+                    directive.settings().generateServerSdk(),
+                    directive.settings().getMemberNullabilityCompatibilityMode()
             );
             generator.run();
         });
@@ -342,7 +343,8 @@ public void generateError(GenerateErrorDirective<TypeScriptCodegenContext, TypeS
                     directive.symbolProvider(),
                     writer,
                     directive.shape(),
-                    directive.settings().generateServerSdk()
+                    directive.settings().generateServerSdk(),
+                    directive.settings().getMemberNullabilityCompatibilityMode()
             );
             generator.run();
         });

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/StructureGenerator.java

@@ -27,6 +27,7 @@
 import software.amazon.smithy.model.shapes.MemberShape;
 import software.amazon.smithy.model.shapes.StructureShape;
 import software.amazon.smithy.model.traits.ErrorTrait;
+import software.amazon.smithy.typescript.codegen.TypeScriptSettings.MemberNullabilityCompatibilityMode;
 import software.amazon.smithy.typescript.codegen.integration.HttpProtocolGeneratorUtils;
 import software.amazon.smithy.utils.SmithyInternalApi;
 
@@ -67,24 +68,29 @@ final class StructureGenerator implements Runnable {
     private final TypeScriptWriter writer;
     private final StructureShape shape;
     private final boolean includeValidation;
+    private final MemberNullabilityCompatibilityMode memberNullabilityCompatibilityMode;
 
     /**
-     * sets 'includeValidation' to 'false' for backwards compatibility.
+     * sets 'includeValidation' to 'false' and backwards compatibility
+     * to {@link MemberNullabilityCompatibilityMode#RELAXED}.
      */
     StructureGenerator(Model model, SymbolProvider symbolProvider, TypeScriptWriter writer, StructureShape shape) {
-        this(model, symbolProvider, writer, shape, false);
+        this(model, symbolProvider, writer, shape, false,
+            MemberNullabilityCompatibilityMode.RELAXED);
     }
 
     StructureGenerator(Model model,
                        SymbolProvider symbolProvider,
                        TypeScriptWriter writer,
                        StructureShape shape,
-                       boolean includeValidation) {
+                       boolean includeValidation,
+                       MemberNullabilityCompatibilityMode memberNullabilityCompatibilityMode) {
         this.model = model;
         this.symbolProvider = symbolProvider;
         this.writer = writer;
         this.shape = shape;
         this.includeValidation = includeValidation;
+        this.memberNullabilityCompatibilityMode = memberNullabilityCompatibilityMode;
     }
 
     @Override
@@ -158,7 +164,7 @@ private void renderNonErrorStructure() {
         }
 
         StructuredMemberWriter config = new StructuredMemberWriter(
-                model, symbolProvider, shape.getAllMembers().values());
+                model, symbolProvider, shape.getAllMembers().values(), this.memberNullabilityCompatibilityMode);
         config.writeMembers(writer, shape);
         writer.closeBlock("}");
         writer.write("");
@@ -255,7 +261,7 @@ private void renderErrorStructure() {
             HttpProtocolGeneratorUtils.writeRetryableTrait(writer, shape, ";");
         }
         StructuredMemberWriter structuredMemberWriter = new StructuredMemberWriter(model, symbolProvider,
-                shape.getAllMembers().values());
+                shape.getAllMembers().values(), this.memberNullabilityCompatibilityMode);
         // since any error interface must extend from JavaScript Error interface, message member is already
         // required in the JavaScript Error interface
         structuredMemberWriter.skipMembers.add("message");

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/StructuredMemberWriter.java

@@ -45,6 +45,7 @@
 import software.amazon.smithy.model.traits.StreamingTrait;
 import software.amazon.smithy.model.traits.Trait;
 import software.amazon.smithy.model.traits.UniqueItemsTrait;
+import software.amazon.smithy.typescript.codegen.TypeScriptSettings.MemberNullabilityCompatibilityMode;
 import software.amazon.smithy.utils.SmithyInternalApi;
 
 /**
@@ -60,12 +61,19 @@ final class StructuredMemberWriter {
     Collection<MemberShape> members;
     String memberPrefix = "";
     boolean noDocs;
+    MemberNullabilityCompatibilityMode memberNullabilityCompatibilityMode;
     final Set<String> skipMembers = new HashSet<>();
 
     StructuredMemberWriter(Model model, SymbolProvider symbolProvider, Collection<MemberShape> members) {
+        this(model, symbolProvider, members, MemberNullabilityCompatibilityMode.RELAXED);
+    }
+
+    StructuredMemberWriter(Model model, SymbolProvider symbolProvider, Collection<MemberShape> members,
+            MemberNullabilityCompatibilityMode memberNullabilityCompatibilityMode) {
         this.model = model;
         this.symbolProvider = symbolProvider;
         this.members = new LinkedHashSet<>(members);
+        this.memberNullabilityCompatibilityMode = memberNullabilityCompatibilityMode;
     }
 
     void writeMembers(TypeScriptWriter writer, Shape shape) {
@@ -79,7 +87,8 @@ void writeMembers(TypeScriptWriter writer, Shape shape) {
             boolean wroteDocs = !noDocs && writer.writeMemberDocs(model, member);
             String memberName = getSanitizedMemberName(member);
             String optionalSuffix = shape.isUnionShape() || !isRequiredMember(member) ? "?" : "";
-            String typeSuffix = isRequiredMember(member) ? " | undefined" : "";
+            String typeSuffix = memberNullabilityCompatibilityMode == MemberNullabilityCompatibilityMode.RELAXED
+                         && isRequiredMember(member) ? " | undefined" : "";
             writer.write("${L}${L}${L}: ${T}${L};", memberPrefix, memberName, optionalSuffix,
                          symbolProvider.toSymbol(member), typeSuffix);
 

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/TypeScriptSettings.java

@@ -34,6 +34,7 @@
 import software.amazon.smithy.model.shapes.ServiceShape;
 import software.amazon.smithy.model.shapes.Shape;
 import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.model.traits.RequiredTrait;
 import software.amazon.smithy.utils.SmithyUnstableApi;
 
 /**
@@ -43,6 +44,7 @@
 public final class TypeScriptSettings {
 
     static final String DISABLE_DEFAULT_VALIDATION = "disableDefaultValidation";
+    static final String MEMBER_NULLABILITY_COMPATIBILITY_MODE = "memberNullabilityCompatibilityMode";
     static final String TARGET_NAMESPACE = "targetNamespace";
     private static final Logger LOGGER = Logger.getLogger(TypeScriptSettings.class.getName());
 
@@ -65,6 +67,8 @@ public final class TypeScriptSettings {
     private boolean isPrivate;
     private ArtifactType artifactType = ArtifactType.CLIENT;
     private boolean disableDefaultValidation = false;
+    private MemberNullabilityCompatibilityMode memberNullabilityCompatibilityMode =
+        MemberNullabilityCompatibilityMode.RELAXED;
     private PackageManager packageManager = PackageManager.YARN;
 
     @Deprecated
@@ -105,6 +109,10 @@ public static TypeScriptSettings from(Model model, ObjectNode config, ArtifactTy
         if (artifactType == ArtifactType.SSDK) {
             settings.setDisableDefaultValidation(config.getBooleanMemberOrDefault(DISABLE_DEFAULT_VALIDATION));
         }
+        settings.setMemberNullabilityCompatibilityMode(
+            config.getStringMember(MEMBER_NULLABILITY_COMPATIBILITY_MODE)
+                .map(s -> MemberNullabilityCompatibilityMode.fromString(s.getValue()))
+                .orElse(MemberNullabilityCompatibilityMode.RELAXED));
 
         settings.setPluginSettings(config);
         return settings;
@@ -295,6 +303,21 @@ public void setDisableDefaultValidation(boolean disableDefaultValidation) {
         this.disableDefaultValidation = disableDefaultValidation;
     }
 
+    /**
+     * Returns the compatibility mode in regards to member nullability.
+     *
+     * @return the configured compatibility mode in regards to member nullability.
+     *  Defaults to {@link MemberNullabilityCompatibilityMode#RELAXED}
+     */
+    public MemberNullabilityCompatibilityMode getMemberNullabilityCompatibilityMode() {
+        return memberNullabilityCompatibilityMode;
+    }
+
+    public void setMemberNullabilityCompatibilityMode(
+        MemberNullabilityCompatibilityMode memberNullabilityCompatibilityMode) {
+        this.memberNullabilityCompatibilityMode = memberNullabilityCompatibilityMode;
+    }
+
     /**
      * Returns the package manager used by the generated package.
      *
@@ -407,6 +430,44 @@ public SymbolProvider createSymbolProvider(Model model, TypeScriptSettings setti
         }
     }
 
+    /**
+     * An enum indicating the compatibility mode in regards to member nullability.
+     */
+    public enum MemberNullabilityCompatibilityMode {
+        /**
+         * This is the current behavior and it will be the default. When set,
+         * it allows a member that has the {@link RequiredTrait} applied to be "undefined".
+         * By doing so it can still be considered a backwards compatible change fo
+         * Smithy services even when the required constraint is dropped from a member .
+         */
+        RELAXED("relaxed"),
+
+        /**
+         * This will dissallow members marked as {@link RequiredTrait} to be "undefined".
+         */
+        STRICT("strict");
+
+        private final String mode;
+
+        MemberNullabilityCompatibilityMode(String mode) {
+            this.mode = mode;
+        }
+
+        public String getMode() {
+            return mode;
+        }
+
+        public static MemberNullabilityCompatibilityMode fromString(String s) {
+            if ("relaxed".equals(s)) {
+                return RELAXED;
+            }
+            if ("strict".equals(s)) {
+                return STRICT;
+            }
+            throw new CodegenException(String.format("Unsupported member nullability compatibility mode: %s", s));
+        }
+    }
+
     public enum PackageManager {
         YARN("yarn"),
         NPM("npm");

smithy-typescript-codegen/src/test/java/software/amazon/smithy/typescript/codegen/StructureGeneratorTest.java

@@ -13,6 +13,7 @@
 import software.amazon.smithy.model.shapes.MemberShape;
 import software.amazon.smithy.model.shapes.OperationShape;
 import software.amazon.smithy.model.shapes.StructureShape;
+import software.amazon.smithy.typescript.codegen.TypeScriptSettings.MemberNullabilityCompatibilityMode;
 
 public class StructureGeneratorTest {
     @Test
@@ -508,7 +509,19 @@ public void skipsFilterOnEncounteringRecursiveShapes() {
                                 + "})");
     }
 
+    @Test
+    public void properlyGeneratesRequiredMessageMemberNotBackwardCompatible() {
+        testStructureCodegenBase("test-required-member.smithy",
+                                "export interface GetFooOutput {\n"
+                                + "  someRequiredMember: string;\n"
+                                + "}\n", MemberNullabilityCompatibilityMode.STRICT);
+    }
+
     private String testStructureCodegen(String file, String expectedType) {
+        return testStructureCodegenBase(file, expectedType, MemberNullabilityCompatibilityMode.RELAXED);
+    }
+
+    private String testStructureCodegenBase(String file, String expectedType, MemberNullabilityCompatibilityMode memberNullabilityCompatibilityMode) {
         Model model = Model.assembler()
                 .addImport(getClass().getResource(file))
                 .assemble()
@@ -521,6 +534,7 @@ private String testStructureCodegen(String file, String expectedType) {
                         .withMember("service", Node.from("smithy.example#Example"))
                         .withMember("package", Node.from("example"))
                         .withMember("packageVersion", Node.from("1.0.0"))
+                        .withMember("memberNullabilityCompatibilityMode", Node.from(memberNullabilityCompatibilityMode.getMode()))
                         .build())
                 .build();
 

smithy-typescript-codegen/src/test/resources/software/amazon/smithy/typescript/codegen/test-required-member.smithy

@@ -0,0 +1,17 @@
+namespace smithy.example
+
+service Example {
+    version: "1.0.0",
+    operations: [GetFoo]
+}
+
+operation GetFoo {
+    input: GetFooInput,
+    output: GetFooOutput
+}
+
+structure GetFooInput {}
+structure GetFooOutput {
+    @required
+    someRequiredMember: String
+}