feat(backend): Added support for customized learning paths to the database learning path provider.

backend/src/services/learning-paths/learning-path-personalization-util.ts

@@ -0,0 +1,42 @@
+import {LearningPathNode} from "../../entities/content/learning-path-node.entity";
+import {Student} from "../../entities/users/student.entity";
+import {Group} from "../../entities/assignments/group.entity";
+import {Submission} from "../../entities/assignments/submission.entity";
+import {getSubmissionRepository} from "../../data/repositories";
+import {LearningObjectIdentifier} from "../../entities/content/learning-object-identifier";
+import {LearningPathTransition} from "../../entities/content/learning-path-transition.entity";
+import {JSONPath} from "jsonpath-plus";
+
+export type PersonalizationTarget = { type: 'student'; student: Student } | { type: 'group'; group: Group };
+/**
+ * Returns the last submission for the learning object associated with the given node and for the student or group
+ */
+export async function getLastSubmissionForCustomizationTarget(node: LearningPathNode, pathFor: PersonalizationTarget): Promise<Submission | null> {
+    const submissionRepo = getSubmissionRepository();
+    const learningObjectId: LearningObjectIdentifier = {
+        hruid: node.learningObjectHruid,
+        language: node.language,
+        version: node.version,
+    };
+    if (pathFor.type === 'group') {
+        return await submissionRepo.findMostRecentSubmissionForGroup(learningObjectId, pathFor.group);
+    } else {
+        return await submissionRepo.findMostRecentSubmissionForStudent(learningObjectId, pathFor.student);
+    }
+}
+
+
+/**
+ * Checks whether the condition of the given transaction is fulfilled by the given submission.
+ * @param transition
+ * @param submitted
+ */
+export function isTransitionPossible(transition: LearningPathTransition, submitted: object | null): boolean {
+    if (transition.condition === 'true' || !transition.condition) {
+        return true; // If the transition is unconditional, we can go on.
+    }
+    if (submitted === null) {
+        return false; // If the transition is not unconditional and there was no submission, the transition is not possible.
+    }
+    return JSONPath({ path: transition.condition, json: submitted }).length === 0;
+}