Count Documents

You can count the number of documents in a collection by calling one of the following methods on a Collection instance:

count_documents(): counts the number of documents that match a query filter. To learn more about creating query filters, see the Specify a Query guide.
estimated_document_count(): estimates the total number of documents in a collection by using collection metadata.

Each method returns the count as a u64 instance.

Note

If you don't pass a filter to the count_documents() method, MongoDB counts the total number of documents in the collection.

Example

This example counts documents in the restaurants collection of the sample_restaurants database. The example uses the estimated_document_count() method to count the total number of documents in the collection. Then, the example uses the count_documents() method to count the number of documents in which the value of the name field includes the string "Sunset".

You can access the documents in the restaurants collection as instances of the Document type or a custom data type. To specify which data type represents the collection's data, replace the <T> type parameter on the highlighted line with one of the following values:

<Document>: Represents collection documents as BSON documents
<Restaurant>: Represents collection documents as instances of the Restaurant struct, defined at the top of the code

Select the Asynchronous or Synchronous tab to see the corresponding code for each runtime:

use std::env;
use mongodb::{
    bson::{ doc, Document },
    Client,
    Collection
};
use serde::{ Deserialize, Serialize };
#[derive(Serialize, Deserialize, Debug)]
struct Restaurant {
    name: String,
    cuisine: String,
}
#[tokio::main]
async fn main() -> mongodb::error::Result<()> {
    let uri = "<connection string>";
    let client = Client::with_uri_str(uri).await?;
    // Replace <T> with the <Document> or <Restaurant> type parameter
    let my_coll: Collection<T> = client
        .database("sample_restaurants")
        .collection("restaurants");
    let ct = my_coll.estimated_document_count().await?;
    println!("Number of documents: {}", ct);
    let ct = my_coll.count_documents(doc! { "name": doc! { "$regex": "Sunset" } }).await?;
    println!("Number of matching documents: {}", ct);
    Ok(())
}

// Your values might differ
Number of documents: 25216
Number of matching documents: 10

use std::env;
use mongodb::{
    bson::{ Document, doc },
    sync::{ Client, Collection }
};
use serde::{ Deserialize, Serialize };
#[derive(Serialize, Deserialize, Debug)]
struct Restaurant {
    name: String,
    cuisine: String,
}
fn main() -> mongodb::error::Result<()> {
    let uri = "<connection string>";
    let client = Client::with_uri_str(uri)?;
    // Replace <T> with the <Document> or <Restaurant> type parameter
    let my_coll: Collection<T> = client
        .database("sample_restaurants")
        .collection("restaurants");
    let ct = my_coll.estimated_document_count().run()?;
    println!("Number of documents: {}", ct);
    let ct = my_coll
        .count_documents(doc! { "name": doc! { "$regex": "Sunset" } })
        .run()?;
    println!("Number of matching documents: {}", ct);
    Ok(())
}

// Your values might differ
Number of documents: 25216
Number of matching documents: 10

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