feat: Store ETag in metadata

src/http/ldp/GetOperationHandler.ts

@@ -1,6 +1,8 @@
+import { getETag } from '../../storage/Conditions';
 import type { ResourceStore } from '../../storage/ResourceStore';
 import { NotImplementedHttpError } from '../../util/errors/NotImplementedHttpError';
 import { assertReadConditions } from '../../util/ResourceUtil';
+import { HH } from '../../util/Vocabularies';
 import { OkResponseDescription } from '../output/response/OkResponseDescription';
 import type { ResponseDescription } from '../output/response/ResponseDescription';
 import type { OperationHandlerInput } from './OperationHandler';
@@ -30,6 +32,10 @@ export class GetOperationHandler extends OperationHandler {
     // Check whether the cached representation is still valid or it is necessary to send a new representation
     assertReadConditions(body, operation.conditions);
 
+    // Add the ETag of the returned representation
+    const etag = getETag(body.metadata);
+    body.metadata.set(HH.terms.etag, etag);
+
     return new OkResponseDescription(body.metadata, body.data);
   }
 }

src/http/ldp/HeadOperationHandler.ts

@@ -1,6 +1,8 @@
+import { getETag } from '../../storage/Conditions';
 import type { ResourceStore } from '../../storage/ResourceStore';
 import { NotImplementedHttpError } from '../../util/errors/NotImplementedHttpError';
 import { assertReadConditions } from '../../util/ResourceUtil';
+import { HH } from '../../util/Vocabularies';
 import { OkResponseDescription } from '../output/response/OkResponseDescription';
 import type { ResponseDescription } from '../output/response/ResponseDescription';
 import type { OperationHandlerInput } from './OperationHandler';
@@ -34,6 +36,10 @@ export class HeadOperationHandler extends OperationHandler {
     // Generally it doesn't make much sense to use condition headers with a HEAD request, but it should be supported.
     assertReadConditions(body, operation.conditions);
 
+    // Add the ETag of the returned representation
+    const etag = getETag(body.metadata);
+    body.metadata.set(HH.terms.etag, etag);
+
     return new OkResponseDescription(body.metadata);
   }
 }

src/http/output/metadata/ModifiedMetadataWriter.ts

@@ -1,7 +1,6 @@
 import type { HttpResponse } from '../../../server/HttpResponse';
-import { getETag } from '../../../storage/Conditions';
 import { addHeader } from '../../../util/HeaderUtil';
-import { DC } from '../../../util/Vocabularies';
+import { DC, HH } from '../../../util/Vocabularies';
 import type { RepresentationMetadata } from '../../representation/RepresentationMetadata';
 import { MetadataWriter } from './MetadataWriter';
 
@@ -15,9 +14,9 @@ export class ModifiedMetadataWriter extends MetadataWriter {
       const date = new Date(modified.value);
       addHeader(input.response, 'Last-Modified', date.toUTCString());
     }
-    const etag = getETag(input.metadata);
+    const etag = input.metadata.get(HH.terms.etag);
     if (etag) {
-      addHeader(input.response, 'ETag', etag);
+      addHeader(input.response, 'ETag', etag.value);
     }
   }
 }

src/util/Vocabularies.ts

@@ -171,6 +171,7 @@ export const FOAF = createVocabulary('http://xmlns.com/foaf/0.1/',
 
 export const HH = createVocabulary('http://www.w3.org/2011/http-headers#',
   'content-length',
+  'etag',
 );
 
 export const HTTP = createVocabulary('http://www.w3.org/2011/http#',

test/unit/http/ldp/GetOperationHandler.test.ts

@@ -5,9 +5,12 @@ import { BasicRepresentation } from '../../../../src/http/representation/BasicRe
 import type { Representation } from '../../../../src/http/representation/Representation';
 import { RepresentationMetadata } from '../../../../src/http/representation/RepresentationMetadata';
 import { BasicConditions } from '../../../../src/storage/BasicConditions';
+import { getETag } from '../../../../src/storage/Conditions';
 import type { ResourceStore } from '../../../../src/storage/ResourceStore';
 import { NotImplementedHttpError } from '../../../../src/util/errors/NotImplementedHttpError';
 import { NotModifiedHttpError } from '../../../../src/util/errors/NotModifiedHttpError';
+import { updateModifiedDate } from '../../../../src/util/ResourceUtil';
+import { CONTENT_TYPE, HH } from '../../../../src/util/Vocabularies';
 
 describe('A GetOperationHandler', (): void => {
   let operation: Operation;
@@ -17,11 +20,13 @@ describe('A GetOperationHandler', (): void => {
   let store: ResourceStore;
   let handler: GetOperationHandler;
   let data: Readable;
-  const metadata = new RepresentationMetadata();
+  let metadata: RepresentationMetadata;
 
   beforeEach(async(): Promise<void> => {
     operation = { method: 'GET', target: { path: 'http://test.com/foo' }, preferences, conditions, body };
     data = { destroy: jest.fn() } as any;
+    metadata = new RepresentationMetadata({ [CONTENT_TYPE]: 'text/turtle' });
+    updateModifiedDate(metadata);
     store = {
       getRepresentation: jest.fn(async(): Promise<Representation> =>
         ({ binary: false, data, metadata } as any)),
@@ -40,6 +45,7 @@ describe('A GetOperationHandler', (): void => {
     const result = await handler.handle({ operation });
     expect(result.statusCode).toBe(200);
     expect(result.metadata).toBe(metadata);
+    expect(metadata.get(HH.terms.etag)?.value).toBe(getETag(metadata));
     expect(result.data).toBe(data);
     expect(store.getRepresentation).toHaveBeenCalledTimes(1);
     expect(store.getRepresentation).toHaveBeenLastCalledWith(operation.target, preferences, conditions);

test/unit/http/ldp/HeadOperationHandler.test.ts

@@ -5,9 +5,12 @@ import { BasicRepresentation } from '../../../../src/http/representation/BasicRe
 import type { Representation } from '../../../../src/http/representation/Representation';
 import { RepresentationMetadata } from '../../../../src/http/representation/RepresentationMetadata';
 import { BasicConditions } from '../../../../src/storage/BasicConditions';
+import { getETag } from '../../../../src/storage/Conditions';
 import type { ResourceStore } from '../../../../src/storage/ResourceStore';
 import { NotImplementedHttpError } from '../../../../src/util/errors/NotImplementedHttpError';
 import { NotModifiedHttpError } from '../../../../src/util/errors/NotModifiedHttpError';
+import { updateModifiedDate } from '../../../../src/util/ResourceUtil';
+import { CONTENT_TYPE, HH } from '../../../../src/util/Vocabularies';
 
 describe('A HeadOperationHandler', (): void => {
   let operation: Operation;
@@ -17,11 +20,13 @@ describe('A HeadOperationHandler', (): void => {
   let store: ResourceStore;
   let handler: HeadOperationHandler;
   let data: Readable;
-  const metadata = new RepresentationMetadata();
+  let metadata: RepresentationMetadata;
 
   beforeEach(async(): Promise<void> => {
     operation = { method: 'HEAD', target: { path: 'http://test.com/foo' }, preferences, conditions, body };
     data = { destroy: jest.fn() } as any;
+    metadata = new RepresentationMetadata({ [CONTENT_TYPE]: 'text/turtle' });
+    updateModifiedDate(metadata);
     store = {
       getRepresentation: jest.fn(async(): Promise<Representation> =>
         ({ binary: false, data, metadata } as any)),
@@ -42,6 +47,7 @@ describe('A HeadOperationHandler', (): void => {
     const result = await handler.handle({ operation });
     expect(result.statusCode).toBe(200);
     expect(result.metadata).toBe(metadata);
+    expect(metadata.get(HH.terms.etag)?.value).toBe(getETag(metadata));
     expect(result.data).toBeUndefined();
     expect(data.destroy).toHaveBeenCalledTimes(1);
     expect(store.getRepresentation).toHaveBeenCalledTimes(1);

test/unit/http/output/metadata/ModifiedMetadataWriter.test.ts

@@ -2,22 +2,21 @@ import { createResponse } from 'node-mocks-http';
 import { ModifiedMetadataWriter } from '../../../../../src/http/output/metadata/ModifiedMetadataWriter';
 import { RepresentationMetadata } from '../../../../../src/http/representation/RepresentationMetadata';
 import type { HttpResponse } from '../../../../../src/server/HttpResponse';
-import { getETag } from '../../../../../src/storage/Conditions';
 import { updateModifiedDate } from '../../../../../src/util/ResourceUtil';
-import { CONTENT_TYPE, DC } from '../../../../../src/util/Vocabularies';
+import { DC, HH } from '../../../../../src/util/Vocabularies';
 
 describe('A ModifiedMetadataWriter', (): void => {
   const writer = new ModifiedMetadataWriter();
 
   it('adds the Last-Modified and ETag header if there is dc:modified metadata.', async(): Promise<void> => {
     const response = createResponse() as HttpResponse;
-    const metadata = new RepresentationMetadata({ [CONTENT_TYPE]: 'text/turtle' });
+    const metadata = new RepresentationMetadata({ [HH.etag]: '123456-turtle' });
     updateModifiedDate(metadata);
     const dateTime = metadata.get(DC.terms.modified)!.value;
     await expect(writer.handle({ response, metadata })).resolves.toBeUndefined();
     expect(response.getHeaders()).toEqual({
       'last-modified': new Date(dateTime).toUTCString(),
-      etag: getETag(metadata),
+      etag: '123456-turtle',
     });
   });