Cassandra 的 Go 開發包：GoCqlTable

GoCqlTable 封裝了 GoCql-driver 目的是簡化 Go 語言操作 Cassandra 數據庫。

示例代碼：

// Generic initialization of gocql
c := gocql.NewCluster("127.0.0.1")
s, err := c.CreateSession()
if err != nil {
    log.Fatalln("Unable to open up a session with the Cassandra database (err=" + err.Error() + ")")
}

// Tell gocqltable to use this session object as the default for new objects
gocqltable.SetDefaultSession(s)


// Now we're ready to create our first keyspace. We start by getting a keyspace object
keyspace := gocqltable.NewKeyspace("gocqltable_test")

// Now lets create that in the database using the simple strategy and durable writes (true)
err = keyspace.Create(map[string]interface{}{
    "class": "SimpleStrategy",
    "replication_factor": 1,
}, true)
if err != nil { // If something went wrong we print the error and quit.
    log.Fatalln(err)
}


// Now that we have a very own keyspace to play with, lets create our first table.

// First we need a Row-object to base the table on. It will later be passed to the table wrapper
// to be used for returning row-objects as the answer to fetch requests.
type User struct{
    Email string // Our primary key
    Password string `password`     // Use Tags to rename fields
    Active bool     `cql:"active"` // If there are multiple tags, use `cql:""` to specify what the table column will be
    Created time.Time
}

// Let's define and instantiate a table object for our user table
userTable := struct{
    recipes.CRUD    // If you looked at the base example first, notice we replaced this line with the recipe
}{
    recipes.CRUD{ // Here we didn't replace, but rather wrapped the table object in our recipe, effectively adding more methods to the end API
        keyspace.NewTable(
            "users",            // The table name
            []string{"email"},  // Row keys
            nil,                // Range keys
            User{},             // We pass an instance of the user struct that will be used as a type template during fetches.
        ),
    },
}

// Lets create this table in our cassandra database
err = userTable.Create()
if err != nil {
    log.Fatalln(err)
}


// Now that we have a keyspace with a table in it: lets make a few rows! In the base example we had to write out the CQL manually, this time
// around, however, we can insert entire User objects.

// Lets instantiate a user object, set its values and insert it
user1 := User{
    Email: "1@example.com",
    Password: "123456",
    Active: true,
    Created: time.Now().UTC(),
}
err = userTable.Insert(user1)
if err != nil {
    log.Fatalln(err)
}


// With our database filled up with users, lets query it and print out the results (containing all users in the database).
rowset, err := userTable.List()
for _, row := range rowset {
    user := row.(*User) // Our row variable is a pointer to "interface{}", and here we type assert it to a pointer to "User"
}
if err != nil {
    log.Fatalln(err)
}


// You can also fetch a single row, obviously
row, err := userTable.Get("1@example.com")
if err != nil {
    log.Fatalln(err)
}
user := row.(*User)


// Lets update this user by changing his password
user.Password = "654321"
err = userTable.Update(user)
if err != nil {
    log.Fatalln(err)
}


// Lets delete user 1@example.com
err = userTable.Delete(user)
if err != nil {
    log.Fatalln(err)
}

// Lets clean up after ourselves by dropping the keyspace.
keyspace.Drop()

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