How to add COUNT field when using getMany in TypeORM

In TypeORM data queries, it is common to need to retrieve both a list of data and the total count of that data. The getMany() method retrieves multiple rows of data but does not directly support returning the total count. To achieve retrieving both the data list and the total count simultaneously when using getMany(), we can use the getManyAndCount() method, which returns an array containing the data list and the total count.

Below is a specific example demonstrating how to use the getManyAndCount() method in TypeORM:

Assume we have a User entity, and we want to query the list of all users along with the total count. We can write the code as follows:

typescript
import { getRepository } from "typeorm";
import { User } from "./entity/User";

async function getUsersAndCount() {
    const userRepository = getRepository(User);
    const [users, count] = await userRepository.createQueryBuilder("user")
        .getManyAndCount();

    console.log("Total users count:", count);
    console.log("Users list:", users);
    return { users, count };
}

getUsersAndCount().then(result => {
    console.log(result);
}).catch(error => {
    console.error("An error occurred:", error);
});

In the above code:

• We first import the getRepository method and the User entity.
• We define an async function getUsersAndCount(), where we create a query builder for the User entity.
• Using createQueryBuilder("user") creates a query, and we use getManyAndCount() to retrieve the user list and the total user count. Here, "user" is an alias used to reference the User entity in the query.
• getManyAndCount() returns an array with two elements: the first is the array of retrieved data, and the second is the total count of the data.
• Finally, we output the total count and the user list in the console.

This approach is ideal for scenarios where you need to retrieve both the data list and the total count simultaneously, such as when implementing pagination. It allows you to conveniently obtain the total number of pages and the data for the current page.