fix(codegen): allow empty string field values for headers

.changeset/small-gifts-tease.md

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

packages/smithy-client/src/index.ts

@@ -1,4 +1,4 @@
-export * from "./NoOpLogger";
+export type { DocumentType, SdkError, SmithyException } from "@smithy/types";
 export * from "./client";
 export * from "./collect-stream-body";
 export * from "./command";
@@ -8,16 +8,17 @@ export * from "./date-utils";
 export * from "./default-error-handler";
 export * from "./defaults-mode";
 export * from "./emitWarningIfUnsupportedVersion";
-export * from "./extensions";
 export * from "./exceptions";
 export * from "./extended-encode-uri-component";
+export * from "./extensions";
 export * from "./get-array-if-single-item";
 export * from "./get-value-from-text-node";
+export * from "./is-serializable-header-value";
 export * from "./lazy-json";
+export * from "./NoOpLogger";
 export * from "./object-mapping";
 export * from "./parse-utils";
 export * from "./resolve-path";
 export * from "./ser-utils";
 export * from "./serde-json";
 export * from "./split-every";
-export type { DocumentType, SdkError, SmithyException } from "@smithy/types";

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 +1035,8 @@ private void writeNormalHeader(GenerationContext context, HttpBinding binding) {
                 : headerValue + defaultValue;
 
             // evaluated value has a function or method call attached
+            context.getWriter()
+                .addImport("isSerializableHeaderValue", null, TypeScriptDependency.AWS_SMITHY_CLIENT);
             headerBuffer.put(headerKey, String.format(
                 "[%s]: [() => isSerializableHeaderValue(%s), () => %s],",
                 context.getStringStore().var(headerKey),
@@ -1093,6 +1095,7 @@ 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();
@@ -1373,7 +1376,13 @@ private String getCollectionInputParam(
             dataSource = "Array.from(" + dataSource + ".values())";
         }
         String collectionTargetValue = getInputValue(context, bindingType, "_entry", targetMember, collectionTarget);
-        String iteratedParam = "(" + dataSource + " || []).map(_entry => " + collectionTargetValue + " as any)";
+        String iteratedParam;
+        if (collectionTargetValue.equals("_entry")) {
+            iteratedParam = "(" + dataSource + " || [])";
+        } else {
+            iteratedParam = "(" + dataSource + " || []).map(_entry => " + collectionTargetValue + " as any)";
+        }
+
         switch (bindingType) {
             case HEADER:
                 return iteratedParam + ".join(', ')";
@@ -2689,20 +2698,25 @@ private String getCollectionOutputParam(
         switch (bindingType) {
             case QUERY_PARAMS:
             case QUERY:
+                if (collectionTargetValue.equals("_entry")) {
+                    return String.format("%1$s", dataSource);
+                }
                 return String.format("%1$s.map(_entry => %2$s as any)", dataSource, collectionTargetValue);
             case LABEL:
                 dataSource = "(" + dataSource + " || \"\")";
                 // Split these values on slashes.
                 outputParam = "" + dataSource + ".split('/')";
 
                 // Iterate over each entry and do deser work.
-                outputParam += ".map(_entry => " + collectionTargetValue + " as any)";
+                if (!collectionTargetValue.equals("_entry")) {
+                    outputParam += ".map(_entry => " + collectionTargetValue + " as any)";
+                }
 
                 return outputParam;
             case HEADER:
                 dataSource = "(" + dataSource + " || \"\")";
                 // Split these values on commas.
-                outputParam = "" + dataSource + ".split(',')";
+                outputParam = dataSource + ".split(',')";
 
                 // Headers that have HTTP_DATE formatted timestamps already contain a ","
                 // in their formatted entry, so split on every other "," instead.
@@ -2719,7 +2733,9 @@ private String getCollectionOutputParam(
                 }
 
                 // Iterate over each entry and do deser work.
-                outputParam += ".map(_entry => " + collectionTargetValue + " as any)";
+                if (!collectionTargetValue.equals("_entry")) {
+                    outputParam += ".map(_entry => " + collectionTargetValue + " as any)";
+                }
 
                 return outputParam;
             default:

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

@@ -47,7 +47,6 @@
 import software.amazon.smithy.typescript.codegen.TypeScriptDependency;
 import software.amazon.smithy.typescript.codegen.TypeScriptWriter;
 import software.amazon.smithy.typescript.codegen.integration.ProtocolGenerator.GenerationContext;
-import software.amazon.smithy.utils.IoUtils;
 import software.amazon.smithy.utils.SmithyInternalApi;
 import software.amazon.smithy.utils.SmithyUnstableApi;
 
@@ -279,16 +278,6 @@ 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.
      *