feat: Add BodyParser for SPARQL updates

package-lock.json

@@ -3080,8 +3080,7 @@
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-      "dev": true
+      "integrity": "sha512-8UEa58QDLauDNfpbrX55Q9jrGHThw2ZMdOky5Gl1CDtVeJDPVrG4Jxx1N8jw2gkWaff5UUuX1KJd+9zGe2B+ZA=="
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@@ -4747,8 +4746,7 @@
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-      "dev": true
+      "integrity": "sha1-egy/ZfQ7WShiWp1NDcVLGMrcfvM="
     },
     "lodash.zip": {
       "version": "4.2.0",
@@ -4889,8 +4887,7 @@
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       "version": "1.2.5",
       "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
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-      "dev": true
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       "version": "1.3.2",
@@ -5672,7 +5669,6 @@
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-      "dev": true,
       "requires": {
         "@rdfjs/data-model": "^1.1.1"
       }
@@ -5681,7 +5677,6 @@
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       "requires": {
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@@ -6551,6 +6546,36 @@
       "integrity": "sha1-PpNdfd1zYxuXZZlW1VEo6HtQhKM=",
       "dev": true
     },
+    "sparqlalgebrajs": {
+      "version": "2.3.1",
+      "resolved": "https://registry.npmjs.org/sparqlalgebrajs/-/sparqlalgebrajs-2.3.1.tgz",
+      "integrity": "sha512-zJ9EEX2BtHjdiSQoWP7fKt2IqD4zi24n3CQtRGOIzh8Hyj2JFMtje68CweaIJgQLN5kNYpNx/VT2F6nxpeIRJg==",
+      "requires": {
+        "@rdfjs/data-model": "^1.1.2",
+        "fast-deep-equal": "^3.1.1",
+        "minimist": "^1.2.5",
+        "rdf-string": "^1.3.1",
+        "sparqljs": "^3.0.1"
+      }
+    },
+    "sparqljs": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/sparqljs/-/sparqljs-3.0.2.tgz",
+      "integrity": "sha512-qmXKWx0ENeLUlvo0tgzcVfnvZnOBkyySvysIf6Y3HgWFKmu1bSrDB9K8siQYJO7jnSihoebtAPv89jvA6by/iw==",
+      "requires": {
+        "n3": "^1.5.0"
+      },
+      "dependencies": {
+        "n3": {
+          "version": "1.5.0",
+          "resolved": "https://registry.npmjs.org/n3/-/n3-1.5.0.tgz",
+          "integrity": "sha512-k4R/EOMnnRYFt+hXgqyKOHjzmshaLuHUFgrz5nsp9nAojCZuAHrro/DsIM2tS0Bgx6ed7DM5Ks3q2teJ8n7HnQ==",
+          "requires": {
+            "queue-microtask": "^1.1.2"
+          }
+        }
+      }
+    },
     "spdx-correct": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/spdx-correct/-/spdx-correct-3.1.0.tgz",

package.json

@@ -40,6 +40,8 @@
     "cors": "^2.8.5",
     "express": "^4.17.1",
     "n3": "^1.4.0",
+    "rdf-terms": "^1.5.1",
+    "sparqlalgebrajs": "^2.3.1",
     "yargs": "^15.4.1"
   },
   "devDependencies": {

src/ldp/http/Patch.ts

@@ -3,4 +3,9 @@ import { Representation } from '../representation/Representation';
 /**
  * Represents the changes needed for a PATCH request.
  */
-export interface Patch extends Representation {}
+export interface Patch extends Representation {
+  /**
+   * The raw body of the PATCH request.
+   */
+  raw: string;
+}

src/ldp/http/SimpleSparqlUpdateBodyParser.ts

@@ -0,0 +1,47 @@
+import { BodyParser } from './BodyParser';
+import { HttpRequest } from '../../server/HttpRequest';
+import { Readable } from 'stream';
+import { readableToString } from '../../util/Util';
+import { SparqlUpdatePatch } from './SparqlUpdatePatch';
+import { translate } from 'sparqlalgebrajs';
+import { UnsupportedHttpError } from '../../util/errors/UnsupportedHttpError';
+import { UnsupportedMediaTypeHttpError } from '../../util/errors/UnsupportedMediaTypeHttpError';
+
+/**
+ * {@link BodyParser} that supports `application/sparql-update` content.
+ * Will convert the incoming update string to algebra in a {@link SparqlUpdatePatch}.
+ * Simple since metadata parsing is not yet implemented.
+ */
+export class SimpleSparqlUpdateBodyParser extends BodyParser {
+  public async canHandle(input: HttpRequest): Promise<void> {
+    const contentType = input.headers['content-type'];
+
+    if (!contentType || contentType !== 'application/sparql-update') {
+      throw new UnsupportedMediaTypeHttpError('This parser only supports SPARQL UPDATE data.');
+    }
+  }
+
+  public async handle(input: HttpRequest): Promise<SparqlUpdatePatch> {
+    try {
+      const sparql = await readableToString(input);
+      const algebra = translate(sparql, { quads: true });
+
+      // Prevent body from being requested again
+      return {
+        algebra,
+        dataType: 'sparql-algebra',
+        raw: sparql,
+        get data(): Readable {
+          throw new Error('Body already parsed');
+        },
+        metadata: {
+          raw: [],
+          profiles: [],
+          contentType: 'application/sparql-update',
+        },
+      };
+    } catch (error) {
+      throw new UnsupportedHttpError(error);
+    }
+  }
+}

src/ldp/http/SparqlUpdatePatch.ts

@@ -0,0 +1,12 @@
+import { Patch } from './Patch';
+import { Update } from 'sparqlalgebrajs/lib/algebra';
+
+/**
+ * A specific type of {@link Patch} corresponding to a SPARQL update.
+ */
+export interface SparqlUpdatePatch extends Patch {
+  /**
+   * Algebra corresponding to the SPARQL update.
+   */
+  algebra: Update;
+}

src/util/Util.ts

@@ -1,3 +1,6 @@
+import arrayifyStream from 'arrayify-stream';
+import { Readable } from 'stream';
+
 /**
  * Makes sure the input path has exactly 1 slash at the end.
  * Multiple slashes will get merged into one.
@@ -8,3 +11,5 @@
  * @returns The potentially changed path.
  */
 export const ensureTrailingSlash = (path: string): string => path.replace(/\/*$/u, '/');
+
+export const readableToString = async(stream: Readable): Promise<string> => (await arrayifyStream(stream)).join('');

test/unit/ldp/http/SimpleSparqlUpdateBodyParser.test.ts

@@ -0,0 +1,41 @@
+import { Algebra } from 'sparqlalgebrajs';
+import { HttpRequest } from '../../../../src/server/HttpRequest';
+import { SimpleSparqlUpdateBodyParser } from '../../../../src/ldp/http/SimpleSparqlUpdateBodyParser';
+import streamifyArray from 'streamify-array';
+import { UnsupportedHttpError } from '../../../../src/util/errors/UnsupportedHttpError';
+import { UnsupportedMediaTypeHttpError } from '../../../../src/util/errors/UnsupportedMediaTypeHttpError';
+import { namedNode, quad } from '@rdfjs/data-model';
+
+describe('A SimpleSparqlUpdateBodyParser', (): void => {
+  const bodyParser = new SimpleSparqlUpdateBodyParser();
+
+  it('only accepts application/sparql-update content.', async(): Promise<void> => {
+    await expect(bodyParser.canHandle({ headers: {}} as HttpRequest)).rejects.toThrow(UnsupportedMediaTypeHttpError);
+    await expect(bodyParser.canHandle({ headers: { 'content-type': 'text/plain' }} as HttpRequest)).rejects.toThrow(UnsupportedMediaTypeHttpError);
+    await expect(bodyParser.canHandle({ headers: { 'content-type': 'application/sparql-update' }} as HttpRequest)).resolves.toBeUndefined();
+  });
+
+  it('errors when handling invalid SPARQL updates.', async(): Promise<void> => {
+    await expect(bodyParser.handle(streamifyArray([ 'VERY INVALID UPDATE' ]) as HttpRequest)).rejects.toThrow(UnsupportedHttpError);
+  });
+
+  it('converts SPARQL updates to algebra.', async(): Promise<void> => {
+    const result = await bodyParser.handle(streamifyArray(
+      [ 'DELETE DATA { <http://test.com/s> <http://test.com/p> <http://test.com/o>}' ],
+    ) as HttpRequest);
+    expect(result.algebra.type).toBe(Algebra.types.DELETE_INSERT);
+    expect((result.algebra as Algebra.DeleteInsert).delete).toBeRdfIsomorphic([ quad(
+      namedNode('http://test.com/s'),
+      namedNode('http://test.com/p'),
+      namedNode('http://test.com/o'),
+    ) ]);
+    expect(result.dataType).toBe('sparql-algebra');
+    expect(result.raw).toBe('DELETE DATA { <http://test.com/s> <http://test.com/p> <http://test.com/o>}');
+    expect(result.metadata).toEqual({
+      raw: [],
+      profiles: [],
+      contentType: 'application/sparql-update',
+    });
+    expect((): any => result.data).toThrow('Body already parsed');
+  });
+});