Mongoose populate

While working on a MERN stack project, mongoose populate, I came across a situation where I wanted to mongoose populate a field but also populate a field inside that populated field I know it's confusing. Bear with me :p. So, I solved it and decided to share it with you all.

There are no joins in MongoDB but sometimes we still want references to documents in other collections. This is where population comes in. 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, 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. Our Person model has it's stories field set to an array of ObjectId s.

Mongoose populate

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. Our Person model has its stories field set to an array of ObjectId s. The ref option is what tells Mongoose which model to use during population, in our case the Story model. However, you should use ObjectId unless you are an advanced user and have a good reason for doing so. So far we haven't done anything much different. We've merely created a Person and a Story. Now let's take a look at populating our story's author using the query builder:.

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In MongoDB, Population is the process of replacing the specified path in the document of one collection with the actual document from the other collection. Need of Population: Whenever in the schema of one collection we provide a reference in any field to a document from any other collection, we need a populate method to fill the field with that document. Example: In the following example, we have one userSchema and another postSchema, in the postSchema we have one field postedBy which references a document from the User model. Step 1: You can visit the link Install mongoose to install the mongoose module. You can install this package by using this command.

In MongoDB, Population is the process of replacing the specified path in the document of one collection with the actual document from the other collection. Need of Population: Whenever in the schema of one collection we provide a reference in any field to a document from any other collection, we need a populate method to fill the field with that document. Example: In the following example, we have one userSchema and another postSchema, in the postSchema we have one field postedBy which references a document from the User model. Step 1: You can visit the link Install mongoose to install the mongoose module. You can install this package by using this command.

Mongoose populate

Mongoose is a popular object-document model ODM library for Node. It includes built-in type casting, validation, query building, and business logic hooks, making it a great choice for many Node. This allows you to link a document in one collection with a document in another collection, and easily retrieve the related documents using a single query. This is especially useful for creating relationships between documents in different collections. For example:. The above code is an example of two-way referencing. Here we retrieve a single post by its title, and then use.

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Next Up Now that we've covered query population, let's take a look at how we can break pieces of our functionality out into reusable and shareable plugins. Keep reading to know ObjectIds can refer to another document in a collection within our database and be populate d when querying:. Take caution when calling its remove method because you'll be removing it from the database, not just the array. Take caution when calling its remove method because you'll be removing it from the database, not just the array. There are two perspectives here. We may find however, if we use the author object, we are unable to get a list of the stories. Just know one thing. In this situation, you will not be able to populate normally. Mongoose can also populate from multiple collections at the same time. Apr 29, Help us improve.

Mongoose has a more powerful alternative called populate , which lets you reference documents in other collections.

Once unsuspended, paras will be able to comment and publish posts again. Instead we could skip populating and directly find the stories we are interested in. That author document will be huge, over 12kb, and large documents lead to performance issues on both server and client. Programmer since age 12, always exploring new tech and fields with a thirst for knowledge. Mongoose Populate Virtuals. This article is being improved by another user right now. For example, the below query won't return any results, even though author is populated. Yes we can say it makes a call to find method behind the scenes. Create Improvement. ObjectIds can refer to another document in a collection within our database and be populate d when querying:. This can be accomplished by passing the usual field name syntax as the second argument to the populate method:.