bring isSerializableHeaderValue into smithy-client

Author: kuhe

.changeset/small-gifts-tease.md

@@ -0,0 +1,5 @@
+---
+"@smithy/smithy-client": patch
+---
+
+serialize empty strings and collections in headers

packages/smithy-client/src/is-serializable-header-value.spec.ts

@@ -0,0 +1,23 @@
+import { isSerializableHeaderValue } from "./is-serializable-header-value";
+
+describe(isSerializableHeaderValue.name, () => {
+  it("considers empty strings serializable", () => {
+    expect(isSerializableHeaderValue("")).toBe(true);
+  });
+
+  it("considers empty collections serializable", () => {
+    expect(isSerializableHeaderValue(new Set())).toBe(true);
+    expect(isSerializableHeaderValue([])).toBe(true);
+  });
+
+  it("considers most falsy data values to be serializable", () => {
+    expect(isSerializableHeaderValue(false)).toBe(true);
+    expect(isSerializableHeaderValue(0)).toBe(true);
+    expect(isSerializableHeaderValue(new Date(0))).toBe(true);
+  });
+
+  it("considered undefined and null to be unserializable", () => {
+    expect(isSerializableHeaderValue(undefined)).toBe(false);
+    expect(isSerializableHeaderValue(null)).toBe(false);
+  });
+});

packages/smithy-client/src/is-serializable-header-value.ts

@@ -0,0 +1,7 @@
+/**
+ * @internal
+ * @returns whether the header value is serializable.
+ */
+export const isSerializableHeaderValue = (value: any) => {
+    return value != null;
+}

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/HttpBindingProtocolGenerator.java

@@ -201,7 +201,6 @@ public void generateSharedComponents(GenerationContext context) {
         generateDocumentBodyShapeDeserializers(context, deserializingDocumentShapes);
         HttpProtocolGeneratorUtils.generateMetadataDeserializer(context, getApplicationProtocol().getResponseType());
         HttpProtocolGeneratorUtils.generateCollectBodyString(context);
-        HttpProtocolGeneratorUtils.generateHttpBindingUtils(context);
 
         writer.write(
             context.getStringStore().flushVariableDeclarationCode()
@@ -965,6 +964,7 @@ private void writeRequestHeaders(
             opening = "const headers: any = {";
             closing = "};";
         } else {
+            writer.addImport("isSerializableHeaderValue", null, TypeScriptDependency.AWS_SMITHY_CLIENT);
             opening = normalHeaderCount > 0
                 ? "const headers: any = map({}, isSerializableHeaderValue, {"
                 : "const headers: any = map({";
@@ -1035,6 +1035,7 @@ private void writeNormalHeader(GenerationContext context, HttpBinding binding) {
                 : headerValue + defaultValue;
 
             // evaluated value has a function or method call attached
+            writer.addImport("isSerializableHeaderValue", null, TypeScriptDependency.AWS_SMITHY_CLIENT);
             headerBuffer.put(headerKey, String.format(
                 "[%s]: [() => isSerializableHeaderValue(%s), () => %s],",
                 context.getStringStore().var(headerKey),
@@ -1093,6 +1094,7 @@ private void writeResponseHeaders(
         TypeScriptWriter writer = context.getWriter();
 
         // Headers are always present either from the default document or the payload.
+        writer.addImport("isSerializableHeaderValue", null, TypeScriptDependency.AWS_SMITHY_CLIENT);
         writer.openBlock("let headers: any = map({}, isSerializableHeaderValue, {", "});", () -> {
             writeContentTypeHeader(context, operationOrError, false);
             injectExtraHeaders.run();

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/HttpProtocolGeneratorUtils.java

@@ -279,16 +279,6 @@ public static void generateCollectBodyString(GenerationContext context) {
         writer.write("");
     }
 
-    /**
-     * Writes any additional utils needed for HTTP protocols with bindings.
-     *
-     * @param context The generation context.
-     */
-    static void generateHttpBindingUtils(GenerationContext context) {
-        TypeScriptWriter writer = context.getWriter();
-        writer.write(IoUtils.readUtf8Resource(HttpProtocolGeneratorUtils.class, "http-binding-utils.ts"));
-    }
-
     /**
      * Writes $retryable key for error if it contains RetryableTrait.
      *