feat: use https://www.npmjs.com/package/rdf-string for serialization/deserialization (#9)

Author: KasperZutterman

package.json

@@ -26,22 +26,23 @@
     "publish": "yarn run build && npm publish --access public"
   },
   "dependencies": {
+    "@dexagod/rdf-retrieval": "^1.0.2",
+    "@rdfjs/data-model": "^1.3.2",
+    "@types/node": "^15.14.1",
+    "@types/yargs": "^17.0.0",
     "express": "^4.17.1",
     "mqtt": "^4.2.8",
     "node-fetch": "^2.6.1",
     "rdf-parse": "^1.8.1",
+    "rdf-serialize": "^1.1.0",
+    "rdf-string": "^1.5.0",
     "rxjs": "^7.2.0",
     "sequelize": "^6.6.4",
     "sqlite3": "^5.0.2",
+    "streamify-array": "^1.0.1",
     "streamify-string": "^1.0.1",
     "typescript": "^4.0.5",
-    "rdf-serialize": "^1.1.0",
-    "streamify-array": "^1.0.1",
-    "yargs": "^17.0.1",
-    "@dexagod/rdf-retrieval": "^1.0.2",
-    "@rdfjs/data-model": "^1.3.2",
-    "@types/node": "^15.14.1",
-    "@types/yargs": "^17.0.0"
+    "yargs": "^17.0.1"
   },
   "devDependencies": {
     "kill-port": "^1.6.1",

src/lib/Page.ts

@@ -1,5 +1,6 @@
 import { IPage } from '../util/Util';
 import type * as RDF from 'rdf-js';
+import * as RdfString from "rdf-string";
 import rdfSerializer from "rdf-serialize";
 import * as f from "@dexagod/rdf-retrieval"
 
@@ -30,4 +31,16 @@ export class Page implements IPage {
 
         return rdfSerializer.serialize(tripleStream, {contentType: contentType});
     }
+
+    public serialize(): object {
+        let serialized: object = {}
+        let triples = []
+        let metadata = []
+
+        this.triples.forEach(triple => {triples.push(RdfString.quadToStringQuad(triple))})
+        serialized['triples'] = triples;
+        this.metadata.forEach(metadata_quad => {metadata.push(RdfString.quadToStringQuad(metadata_quad))})
+        serialized['metadata'] = metadata;
+        return serialized;
+    }
 }

src/lib/Source.ts

@@ -3,6 +3,7 @@ import { Page } from "./Page";
 import { Readable } from 'stream';
 
 import type * as RDF from 'rdf-js';
+import * as RdfString from "rdf-string";
 import { literal, namedNode, quad } from '@rdfjs/data-model';
 
 export abstract class Source implements ISource {
@@ -49,7 +50,7 @@ export abstract class Source implements ISource {
     private async importPagesWithoutIndex(pages: Page[]): Promise<void> {
         let amount = await this.databaseModel.count();
         pages.forEach(async page => {
-            let pageJSON = JSON.stringify(page)
+            let pageJSON = JSON.stringify(page.serialize())
 
             let id = (amount + 1).toString();
             amount++;
@@ -60,7 +61,7 @@ export abstract class Source implements ISource {
 
     private async importPagesWithIndex(pages: Map<string, Page>): Promise<void> {
         for (const [id, page] of pages.entries()) {
-            let pageJSON = JSON.stringify(page)
+            let pageJSON = JSON.stringify(page.serialize())
 
             await this.databaseModel.create({ id: id, page: pageJSON });
         };
@@ -71,10 +72,12 @@ export abstract class Source implements ISource {
         let metadata: RDF.Quad[] = [];
 
         json['triples'].forEach(quad_ => {
-            triples.push(quad(namedNode(quad_['subject']['value']), namedNode(quad_['predicate']['value']), namedNode(quad_['object']['value'])))
+            triples.push(RdfString.stringQuadToQuad(quad_))
+            //triples.push(quad(namedNode(quad_['subject']['value']), namedNode(quad_['predicate']['value']), namedNode(quad_['object']['value'])))
         });
         json['metadata'].forEach(quad_ => {
-            metadata.push(quad(namedNode(quad_['subject']['value']), namedNode(quad_['predicate']['value']), namedNode(quad_['object']['value'])))
+            metadata.push(RdfString.stringQuadToQuad(quad_))
+            //metadata.push(quad(namedNode(quad_['subject']['value']), namedNode(quad_['predicate']['value']), namedNode(quad_['object']['value'])))
         });
 
         return new Page(triples, metadata);