feat(api): add methods to manage backlinks more efficiently

packages/unigraph-dev-backend/src/custom.d.ts

@@ -62,6 +62,7 @@ declare type EventUpdateSPO = {
     type: 'event',
     event: 'update_spo',
     objects: string[],
+    isDelete?: boolean,
     subIds: any[] | any,
     id: number
 }
@@ -318,4 +319,21 @@ declare type EventEnablePackage = {
     event: 'enable_package',
     packageName: string
     id: number
+}
+
+declare type EventRecalculateBacklinks = {
+    type: 'event',
+    event: 'recalculate_backlinks',
+    id: number,
+    fromUids: string[],
+    toUids: string[],
+    depth?: number
+}
+
+declare type EventAddBacklinks = {
+    type: 'event',
+    event: 'add_backlinks',
+    id: number,
+    fromUids: string[],
+    toUids: string[],
 }

packages/unigraph-dev-backend/src/localUnigraphApi.ts

@@ -223,18 +223,20 @@ export function getLocalUnigraphAPI(
             });
         },
         // latertodo
-        updateTriplets: async (objects) => {
+        updateTriplets: async (objects, isDelete, subIds) => {
             if (Array.isArray(objects)) {
                 // is triplet
                 const updateTriplets = new dgraph.Mutation();
-                updateTriplets.setSetNquads(objects.join('\n'));
+                if (!isDelete) updateTriplets.setSetNquads(objects.join('\n'));
+                else updateTriplets.setDelNquads(objects.join('\n'));
                 const result = await client.createDgraphUpsert({
                     query: false,
                     mutations: [updateTriplets],
                 });
                 callHooks(states.hooks, 'after_object_changed', {
                     subscriptions: states.subscriptions,
                     caches: states.caches,
+                    subIds,
                 });
             }
         },
@@ -543,6 +545,43 @@ export function getLocalUnigraphAPI(
             });
             return result;
         },
+        recalculateBacklinks: async (fromUids, toUids, depth = 50) => {
+            const queries = fromUids.map(
+                (el) => `(func: uid(${el})) @recurse(depth: ${depth}) {uid unigraph.id expand(_userpredicate_) }`,
+            );
+            const res: any[] = (await states.localApi.getQueries(queries)).map((el: any[]) => el[0]);
+            const toDel: string[] = [];
+            res.forEach((el: any) => {
+                const str = JSON.stringify(el);
+                toUids.forEach((it) => {
+                    if (!str.includes(`"${it}"`)) {
+                        toDel.push(`<${it}> <unigraph.origin> <${el.uid}> .`);
+                    }
+                });
+            });
+            const updater = new dgraph.Mutation();
+            updater.setDelNquads(toDel.join('\n'));
+            const result = await client.createDgraphUpsert({
+                query: false,
+                mutations: [updater],
+            });
+            return result;
+        },
+        addBacklinks: async (fromUids, toUids) => {
+            const toAdd: string[] = [];
+            fromUids.forEach((el) => {
+                toUids.forEach((it) => {
+                    toAdd.push(`<${it}> <unigraph.origin> <${el}> .`);
+                });
+            });
+            const updater = new dgraph.Mutation();
+            updater.setSetNquads(toAdd.join('\n'));
+            const result = await client.createDgraphUpsert({
+                query: false,
+                mutations: [updater],
+            });
+            return result;
+        },
     };
 
     return api;

packages/unigraph-dev-backend/src/server.ts

@@ -17,6 +17,7 @@ import { Unigraph } from 'unigraph-dev-common/lib/types/unigraph';
 import stringify from 'json-stable-stringify';
 import DgraphClient from './dgraphClient';
 import {
+    EventAddBacklinks,
     EventAddNotification,
     EventAddUnigraphPackage,
     EventCreateDataByJson,
@@ -39,6 +40,7 @@ import {
     EventImportObjects,
     EventProxyFetch,
     EventQueryByStringWithVars,
+    EventRecalculateBacklinks,
     EventReorderItemInArray,
     EventResponser,
     EventRunExecutable,
@@ -477,7 +479,7 @@ export default async function startServer(client: DgraphClient) {
         },
 
         "update_spo": function (event: EventUpdateSPO, ws: IWebsocket) {
-            localApi.updateTriplets(event.objects).then((_: any) => {
+            localApi.updateTriplets(event.objects, event.isDelete, event.subIds).then((_: any) => {
                 callHooks(serverStates.hooks, "after_object_changed", {subscriptions: serverStates.subscriptions, caches: caches, subIds: event.subIds, ofUpdate: event.id})
                 ws.send(makeResponse(event, true))
             }).catch((e: any) => ws.send(makeResponse(event, false, {"error": e.toString()})));
@@ -700,6 +702,18 @@ export default async function startServer(client: DgraphClient) {
                 .catch((e: any) => ws.send(makeResponse(event, false, {"error": e.toString()})));
             callHooks(serverStates.hooks, "after_object_changed", {subscriptions: serverStates.subscriptions, caches: caches});
             ws.send(makeResponse(event, true, {result: res}))
+        },
+
+        "recalculate_backlinks": async function (event: EventRecalculateBacklinks, ws: IWebsocket) {
+            const res = await serverStates.localApi.recalculateBacklinks(event.fromUids, event.toUids, event.depth)
+                .catch((e: any) => ws.send(makeResponse(event, false, {"error": e.toString()})));
+            ws.send(makeResponse(event, true, {result: res}))
+        },
+
+        "add_backlinks": async function (event: EventAddBacklinks, ws: IWebsocket) {
+            const res = await serverStates.localApi.addBacklinks(event.fromUids, event.toUids)
+                .catch((e: any) => ws.send(makeResponse(event, false, {"error": e.toString()})));
+            ws.send(makeResponse(event, true, {result: res}))
         }
     };
 

packages/unigraph-dev-common/src/api/unigraph.ts

@@ -423,9 +423,9 @@ export default function unigraph(url: string, browserId: string): Unigraph<WebSo
         deleteObject: (uid, permanent?) => {
             sendEvent(connection, 'delete_unigraph_object', { uid, permanent });
         },
-        updateTriplets: (objects, subIds?) => {
+        updateTriplets: (objects, isDelete, subIds) => {
             // TODO: This is very useless, should be removed once we get something better
-            sendEvent(connection, 'update_spo', { objects, subIds });
+            sendEvent(connection, 'update_spo', { objects, isDelete, subIds });
         },
         updateObject: (uid, newObject, upsert = true, pad = true, subIds, origin, eagarlyUpdate) =>
             new Promise((resolve, reject) => {
@@ -691,6 +691,24 @@ export default function unigraph(url: string, browserId: string): Unigraph<WebSo
                 };
                 sendEvent(connection, 'enable_package', { packageName }, id);
             }),
+        recalculateBacklinks: (fromUids, toUids, depth) =>
+            new Promise((resolve, reject) => {
+                const id = getRandomInt();
+                callbacks[id] = (response: any) => {
+                    if (response.success && response.results) resolve(response.results);
+                    else reject(response);
+                };
+                sendEvent(connection, 'recalculate_backlinks', { fromUids, toUids, depth }, id);
+            }),
+        addBacklinks: (fromUids, toUids) =>
+            new Promise((resolve, reject) => {
+                const id = getRandomInt();
+                callbacks[id] = (response: any) => {
+                    if (response.success && response.results) resolve(response.results);
+                    else reject(response);
+                };
+                sendEvent(connection, 'add_backlinks', { fromUids, toUids }, id);
+            }),
     };
 
     return api;

packages/unigraph-dev-common/src/types/unigraph.ts

@@ -246,7 +246,7 @@ export interface Unigraph<TT = WebSocket | false> {
     /**
      * Updates objects simply using the SPO triplet format.
      */
-    updateTriplets(triplets: any[], subIds?: any[] | any): any;
+    updateTriplets(triplets: any[], isDelete?: boolean, subIds?: any[] | any): any;
     /**
      * Updates an existing object by its UID and describing the new object.
      *
@@ -414,5 +414,22 @@ export interface Unigraph<TT = WebSocket | false> {
     leaseUid?(): string;
     disablePackage?(packageName: string): any;
     enablePackage?(packageName: string): any;
+    /**
+     * Recalculates backlinks from a set of objects, to a set of children.
+     *
+     * This is done by fetching everything of the given fromUids and see if they still lead to the toUids.
+     * If not, the backlink is removed.
+     *
+     * @param fromUids A list of objects to fetch.
+     * @param toUids
+     * @param depth
+     */
+    recalculateBacklinks(fromUids: string[], toUids: string[], depth?: number): any;
+    /**
+     * Adds a list of fromUids (parents) to backlinks (unigraph.origin) of toUids (children).
+     * @param fromUids
+     * @param toUids
+     */
+    addBacklinks(fromUids: string[], toUids: string[]): any;
 }
 /** End of unigraph interface */ // Don't remove this line - needed for Monaco to work