mongotemplate.upsert用法

`MongoTemplate`'s `upsert` method is used to perform an "upsert" operation in MongoDB. "Upsert" is a combination of "update" and "insert" operations. It updates an existing document if it matches the query criteria, or inserts a new document if no matching document is found.

Here's an example of how to use the `upsert` method in `MongoTemplate`:

import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.query.Criteria;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.data.mongodb.core.query.Update;

public class UpsertExample {
    private MongoTemplate mongoTemplate;

    public void upsertDocument(String id, String name, int age) {
        // Create a query to find the document by id
        Query query = new Query(Criteria.where("_id").is(id));

        // Create an update object with the new values
        Update update = new Update();
        update.set("name", name);
        update.set("age", age);

        // Perform the upsert operation
        mongoTemplate.upsert(query, update, YourDocumentClass.class);
    }
}

In this example, we have a method called `upsertDocument` that performs an upsert operation. It takes an `id`, `name`, and `age` as parameters. First, we create a `Query` object to find the document based on the specified `id`. Then, we create an `Update` object with the new values for `name` and `age`. Finally, we call the `upsert` method on `MongoTemplate` with the query, update, and the class of the document you want to upsert.

Make sure to replace `YourDocumentClass` with the actual class representing your MongoDB document.

Note that `upsert` is just one of the many methods available in `MongoTemplate` for performing CRUD operations in MongoDB. You can refer to the Spring Data MongoDB documentation for more details on using `MongoTemplate` and other features it provides.