Involvierte Definitionen
:Veranstaltung
: DEDSReferenz
: Einsendeaufgaben KE6
⠀
Beispiel: Erstellen eines Embeddings in MongoDB
Sei folgendes Beispiel gegeben:
Wir wollen die Tabellenstruktur in folgendes Embedding überführen:
Hierzu führen wir folgende Befehle aus:
Einbetten der Employees in Department
db.Department.aggregate([ { $lookup: { from: "Employee", localField: "_id", foreignField: "department_id", as: "employees" } }, { $project: { "employees.department_id": 0 } }, { $merge: { into: "Department", whenMatched: "replace", whenNotMatched: "discard" } }, ])
Einbetten des Departments in Project
db.Project.aggregate([ { $lookup: { from: "Department", localField: "department_id", foreignField: "_id", as: "department" } }, { $unwind: "$department" // Flatten the array into a single object }, { $project: { "department_id": 0, "department.city": 0, "department.zip_code": 0, "department.employees": 0 } }, { $merge: { into: "Project", whenMatched: "replace", whenNotMatched: "discard" } }, ])