Find many in mongoose
SEE VIDEO BY TOPIC: MongoDB Tutorial #15 - Relational DataContent:
- MongoDB Many-to-Many Relationship with Mongoose examples
- Find By ID in Mongoose
- Subscribe to RSS
- Mongoose findOne with Multiple Conditions
- Subscribe to RSS
- Mongoose Find All
- How find() Works in Mongoose
- How to optimize MongoDB & Mongoose for Performance
- Mongoose Relationships Tutorial
- Express Tutorial Part 3: Using a Database (with Mongoose)
MongoDB Many-to-Many Relationship with Mongoose examples
When working with databases, data retrieval is the most used operation of all the CRUD operations. When working with mongoose and MongoDB, documents of a collection can be retrieved using various methods.
In this article, we will discuss such methods of retrieving documents from a collection in MongoDB. And we will use the postman tool for executing routes. The most common method for data retrieval in both mongoose, as well as mongo shell, is the find method.
The find methods retrieve all the documents of a collection when an empty object is passed. The find method has two parameters — an object and a callback function. Here, we are passing an empty object. The callback function also has two parameters — error if any occurs and the returning value.
As mentioned earlier, the find method returns all the documents when an empty object is passed. Now the find method will return only those documents where age is But did you notice one thing? The find method returns all the fields of a document. We can also modify the fields in the output. Suppose we want only the name field of all the documents in the collection. There is an optional parameter of the find method that is passed as the second parameter before the callback function.
It specifies which fields should be present in the output. The age field is ignored in the output. Unlike the find method, the findOne method returns only one document. If an empty object is passed to the findOne method, it returns the very first document of the collection. It will return only the first document that matches the condition. All other documents that match the condition will be ignored. This method is called findById method.
So the findById method only returns a single document. So we discussed three methods for retrieving data from MongoDB in mongoose. The find method is most commonly used because it gives us more options.
People usually confuse the find method for the findAll method. But there does not exist any such method in mongoose. The find method can be used for retrieving all the documents from a collection. The findOne and findById method returns only a single document, but still are very useful. So we have a few options for data retrieval in mongoose.
We hate spam and make it easy to unsubscribe. Log In Try Free. Written by Data Pilot. MongoDB Mongoose. Pilot the ObjectRocket Platform Free! Get Started. Related Topics:.
Keep in the know! Platform Pricing Cost of Ownership.
Find By ID in Mongoose
Mongoose has a more powerful alternative called populate , which lets you reference documents in other collections. Population is the process of automatically replacing the specified paths in the document with document s from other collection s. We may populate a single document, multiple documents, a plain object, multiple plain objects, or all objects returned from a query. Let's look at some examples. So far we've created two Models.
The findOne method is one of the two popular methods that are used to retrieve data from MongoDB collections in mongoose. As the name suggests, the findOne methods find a single document only. Usually, we provide a query to match a document. The findOne method also works fine if an empty object is passed to it.
Subscribe to RSS
Mongoose findOne with Multiple Conditions
The exports object of the mongoose module is an instance of this class. Most apps will only use this one instance. The Mongoose Decimal SchemaType. Used for declaring paths in your schema that should be bit decimal floating points.
Subscribe to RSS
When working with databases, data retrieval is the most used operation of all the CRUD operations. When working with mongoose and MongoDB, documents of a collection can be retrieved using various methods. In this article, we will discuss such methods of retrieving documents from a collection in MongoDB.SEE VIDEO BY TOPIC: 12 Aggregation Example 4 $group by multiple fields - MongoDB Aggregation Tutorial
Mongoose models provide several static helper functions for CRUD operations. Each of these functions returns a mongoose Query object. A mongoose query can be executed in one of two ways. First, if you pass in a callback function, Mongoose will execute the query asynchronously and pass the results to the callback. When executing a query with a callback function, you specify your query as a JSON document. Mongoose executed the query and passed the results to callback.
Mongoose Find All
One will be for publishers and another will be for games. Then, we will have another collection to represent a game. So in the object here, we have a game that references the id of a publisher document. This is the reference approach. It feels similar to how things might be done in a relational database, but there is a difference.
This page documents the mongo shell method, and does not refer to the MongoDB Node. Selects documents in a collection or view and returns a cursor to the selected documents. The projection parameter determines which fields are returned in the matching documents. The projection parameter takes a document of the following form:.
How find() Works in Mongoose
It then goes on to show how we can use Mongoose to provide database access for the LocalLibrary website. It explains how object schema and models are declared, the main field types, and basic validation. It also briefly shows a few of the main ways in which you can access model data.
How to optimize MongoDB & Mongoose for Performance
There's some confusion on the internet about what happens when you call Model. Make no mistake, Model. But there's some confusion about Model. In this article, I'll provide a conceptual overview of what happens when you call Model.
Mongoose Relationships Tutorial
Express Tutorial Part 3: Using a Database (with Mongoose)