Connecting from Go
Before we proceed:
Install the
go-tarantoollibrary.Start Tarantool (locally or in Docker) and make sure that you have created and populated a database as we suggested earlier:
box.cfg{listen = 3301} s = box.schema.space.create('tester') s:format({ {name = 'id', type = 'unsigned'}, {name = 'band_name', type = 'string'}, {name = 'year', type = 'unsigned'} }) s:create_index('primary', { type = 'hash', parts = {'id'} }) s:create_index('secondary', { type = 'hash', parts = {'band_name'} }) s:insert{1, 'Roxette', 1986} s:insert{2, 'Scorpions', 2015} s:insert{3, 'Ace of Base', 1993}
Important
Please do not close the terminal window where Tarantool is running – you’ll need it soon.
In order to connect to Tarantool as an administrator, reset the password for the
adminuser:box.schema.user.passwd('pass')
To get connected to the Tarantool server, write a simple Go program:
package main
import (
"fmt"
"github.com/tarantool/go-tarantool"
)
func main() {
conn, err := tarantool.Connect("127.0.0.1:3301", tarantool.Opts{
User: "admin",
Pass: "pass",
})
if err != nil {
log.Fatalf("Connection refused")
}
defer conn.Close()
// Your logic for interacting with the database
}
The default user is guest.
To insert a tuple into a space, use Insert:
resp, err = conn.Insert("tester", []interface{}{4, "ABBA", 1972})
This inserts the tuple (4, "ABBA", 1972) into a space named tester.
The response code and data are available in the tarantool.Response structure:
code := resp.Code
data := resp.Data
To select a tuple from a space, use Select:
resp, err = conn.Select("tester", "primary", 0, 1, tarantool.IterEq, []interface{}{4})
This selects a tuple by the primary key with offset = 0 and limit = 1
from a space named tester (in our example, this is the index named primary,
based on the id field of each tuple).
Next, select tuples by a secondary key.
resp, err = conn.Select("tester", "secondary", 0, 1, tarantool.IterEq, []interface{}{"ABBA"})
Finally, it would be nice to select all the tuples in a space. But there is no one-liner for this in Go; you would need a script like this one.
For more examples, see https://github.com/tarantool/go-tarantool#usage
Update a field value using Update:
resp, err = conn.Update("tester", "primary", []interface{}{4}, []interface{}{[]interface{}{"+", 2, 3}})
This increases by 3 the value of field 2 in the tuple with id = 4.
If a tuple with this id doesn’t exist, Tarantool will return an error.
Now use Replace to totally replace the tuple that matches the
primary key. If a tuple with this primary key doesn’t exist, Tarantool will
do nothing.
resp, err = conn.Replace("tester", []interface{}{4, "New band", 2011})
You can also update the data using Upsert that works similarly
to Update, but creates a new tuple if the old one was not found.
resp, err = conn.Upsert("tester", []interface{}{4, "Another band", 2000}, []interface{}{[]interface{}{"+", 2, 5}})
This increases by 5 the value of the third field in the tuple with id = 4, or
inserts the tuple (4, "Another band", 2000) if a tuple with this id
doesn’t exist.
To delete a tuple, use connection.Delete:
resp, err = conn.Delete("tester", "primary", []interface{}{4})
To delete all tuples in a space (or to delete an entire space), use Call.
We’ll focus on this function in more detail in the
next section.
To delete all tuples in a space, call space:truncate:
resp, err = conn.Call("box.space.tester:truncate", []interface{}{})
To delete an entire space, call space:drop.
This requires connecting to Tarantool as the admin user:
resp, err = conn.Call("box.space.tester:drop", []interface{}{})
Switch to the terminal window where Tarantool is running.
Note
If you don’t have a terminal window with remote connection to Tarantool, check out these guides:
Define a simple Lua function:
function sum(a, b)
return a + b
end
Now we have a Lua function defined in Tarantool. To invoke this function from
go, use Call:
resp, err = conn.Call("sum", []interface{}{2, 3})
To send bare Lua code for execution, use Eval:
resp, err = connection.Eval("return 4 + 5", []interface{}{})
There are two more connectors from the open-source community:
See the feature comparison table of all Go connectors available.