![]() Would find that the 2nd story has 0 fans: const stories = await Story. If you were to populate() using the limit option, you We may populate a single document, multiple documents, a plain object, multiple plain objects, or all objects returned from a query. Population is the process of automatically replacing the specified paths in the document with document(s) from other collection(s). Mongoose has a more powerful alternative called populate(), which lets you reference documents in other collections. In the first stage of the Aggregations view, select the $lookup operator.MongoDB has the join-like $lookup aggregation operator in versions >= 3.2. In the service collection view, select the Aggregations tab. On the left menu pane, you should see the business database and the two collections we created. In Compass, connect to the business database on localhost. The common factor between these two collections is the _id of the company collection and this is referenced as the companyId in the service collection.įor the visual clarity and ease of understanding, I recommend that you use MongoDB's Compass to implement the joins between the two collections. Say we want to create a report that shows us only services that offered by registered companies.īecause the data we need spans across two collections, the company and service collection, we would need to do a join to generate this report. There are 7 services offered by these companies and all services are active. ![]() 4 out of the 10 companies are registered. Some points about the data we just added to our collections. "serviceName": "Rebar & Wire Mesh Install", "_id": "cef57a11-acac-416d-ab3a-096a17722a84", The operation would correspond to the following pseudo-SQL statement: SELECT,
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |