crud basics, mongo.db with go

To perform CRUD (Create, Read, Update, Delete) operations with MongoDB using the Go programming language, you will need to follow a series of steps. Here is an explanation of each step:

1. Import Dependencies: Start by importing the necessary dependencies in your Go code. You will need to import the official MongoDB driver for Go, which provides the necessary functions and methods to interact with MongoDB.

go import ( "context" "go.mongodb.org/mongo-driver/mongo" "go.mongodb.org/mongo-driver/mongo/options" )

1. Establish Connection: Next, establish a connection to the MongoDB database. This involves creating a client object using the connection string and options. The connection string typically includes the database URL, authentication credentials, and other parameters.

```go func main() { // Set up client options clientOptions := options.Client().ApplyURI("mongodb://localhost:27017")

   // Connect to MongoDB
   client, err := mongo.Connect(context.TODO(), clientOptions)
   if err != nil {
       log.Fatal(err)
   }

   // Disconnect from MongoDB
   err = client.Disconnect(context.TODO())
   if err != nil {
       log.Fatal(err)
   }
   fmt.Println("Connection closed.")

} ```

1. Select Database and Collection: Once the connection is established, you need to select a specific database and collection to work with. In MongoDB, a database can contain multiple collections, similar to tables in relational databases.

go // Select database and collection database := client.Database("mydatabase") collection := database.Collection("mycollection")

1. Create Document: To create a new document in the collection, you need to define the structure of the document and insert it into the collection.

```go // Define a struct for the document type Person struct { Name string Email string }

// Create a new document person := Person{Name: "John Doe", Email: "[email protected]"}

// Insert the document into the collection _, err = collection.InsertOne(context.TODO(), person) if err != nil { log.Fatal(err) } ```

1. Read Documents: To read documents from the collection, you can use various methods provided by the MongoDB driver. For example, you can use the Find() method to retrieve all documents that match a specific query.

```go // Define a filter for the query filter := bson.M{"name": "John Doe"}

// Find documents that match the filter cursor, err := collection.Find(context.TODO(), filter) if err != nil { log.Fatal(err) }

// Iterate over the cursor and process the documents defer cursor.Close(context.TODO()) for cursor.Next(context.TODO()) { var result bson.M err := cursor.Decode(&result) if err != nil { log.Fatal(err) } fmt.Println(result) } ```

1. Update Document: To update a document in the collection, you can use the UpdateOne() method. This method allows you to specify a filter to match the document and an update operation to perform on the matched document.

```go // Define a filter for the update operation filter := bson.M{"name": "John Doe"}

// Define an update operation update := bson.M{"$set": bson.M{"email": "[email protected]"}}

// Update the document _, err = collection.UpdateOne(context.TODO(), filter, update) if err != nil { log.Fatal(err) } ```

1. Delete Document: To delete a document from the collection, you can use the DeleteOne() method. This method allows you to specify a filter to match the document to be deleted.

```go // Define a filter for the delete operation filter := bson.M{"name": "John Doe"}

// Delete the document _, err = collection.DeleteOne(context.TODO(), filter) if err != nil { log.Fatal(err) } ```

These are the basic steps involved in performing CRUD operations with MongoDB using the Go programming language. You can build upon these steps to create more complex applications that interact with the database. Remember to handle errors appropriately and close the database connection when you are done with it.