Getting Started Guide

Setup

Create a basic go project

export GOPATH=$HOME/dosa-sample
mkdir -p $GOPATH/src/dosa-sample
cd $GOPATH/src/dosa-sample

Install glide

If you don't already have it, see https://github.com/Masterminds/glide/blob/master/README.md#install for specific instructions.

Make sure glide and $GOPATH/bin are in your $PATH:

Starting in the base directory of your sources:

export PATH="$PATH:$GOPATH/bin"

Create at least one entity

In your code, create an object that embeds (github.com/uber-go/dosa).Entity, we'll call it entities.go:

package main

import (
    "time"

    "github.com/uber-go/dosa"
)

type MyFirstDosaObject struct {
    dosa.Entity `dosa:"primaryKey=((K1, K2), K3)"`
    K1 dosa.UUID
    K2 string
    K3 int64
    C1 time.Time
}

This example describes an object with a partitioning key of (K1, K2) and a clustering key of K3. There is a single non-key field, C1.

Initialize client

Create main.go as follows:

package main

import (
    "context"
    "github.com/uber-go/dosa"
    _ "github.com/uber-go/dosa/connectors/cassandra"
)

func main() {
    registry, err := dosa.NewRegistrar("dosakeyspace", "appname", &MyFirstDosaObject{})
    if err != nil {
            panic(err.Error())
    }
    connector, err := dosa.GetConnector("cassandra", nil)
    if err != nil {
            panic(err.Error())
    }
    client := dosa.NewClient(registry, connector)
    if err := client.Initialize(context.TODO()); err != nil {
            panic(err.Error())
    }
    if err := client.Upsert(context.TODO(), dosa.All(), &MyFirstDosaObject{K1: dosa.NewUUID(), K2: "testdata", K3: 1, C1: time.Now()}); err != nil {
            panic(err.Error())
    }
}

Install the DOSA library

glide init

Install the DOSA CLI

go get -u github.com/uber-go/dosa/cmd/dosa

The dosa binary should now be installed in $GOPATH/bin.

ls -l $GOPATH/bin/dosa

Get all the dependencies

glide install
go build

Dump your schema definitions

Do this to check for errors in your entities, use the CLI's schema dump command, prefix is required:

dosa schema dump

This command takes an optional list of directories to look for entities. If none are provided, it will default to the current directory. Since the example assumes entities are defined in ./entities.go, no arguments are needed.

Install your schema into a cassandra instance

This assumes you already have Cassandra running on your local machine.

echo "create keyspace dosakeyspace with replication = { 'class': 'SimpleStrategy', 'replication_factor': 1 };" | cqlsh
dosa schema dump | cqlsh

Run the app

Now just build and run the app like this:

go build
./dosa-sample

If it worked, you'll find a row in the Cassandra database:

echo 'select * from dosakeyspace.myfirstdosaobject;' | cqlsh
 k1                                   | k2       | k3 | c1
--------------------------------------+----------+----+---------------------------------
 b68281f9-4096-4e23-9359-a3b28ebc026e | testdata |  1 | 2017-09-27 10:44:12.799000+0000