Modern Cassandra driver for Elixir, using cqerl underneath.
Add cqex to your application's mix.exs:
defp deps do
[
# ...
{:cqex, "~> 0.2.0"},
# ...
]
endAnd update your applications list in the project:
def application do
[applications: [:cqex]]
endIf you're using a single cluster, in your project's config/config.exs:
use Mix.Config
config :cqerl,
cassandra_nodes: [{"10.0.0.1", 9042}, {"10.0.0.2", 9042}],
keyspace: "keyspace"Then, create a transient client connection
client = CQEx.Client.new!Fetch the complete list of users, and creating a list out of it using Enum
all_users = client |> CQEx.Query.call!("SELECT * FROM users;") |> Enum.to_list
# => [ list of users... ]
all_users[0]
# => %{ ... first_user ... }Chain queries and using Stream and Enum to get the result set in small pages.
alias CQEx.Query, as: Q
base = %Q{
statement: "INSERT INTO animals (name, legs, friendly) values (?, ?, ?);",
values: %{ legs: 4, friendly: true }
}
^base = Q.new
|> Q.statement("INSERT INTO animals (name, legs, friendly) values (?, ?, ?);")
|> Q.put(:legs, 4)
|> Q.put(:friendly, true)
animals_by_pair = client
|> Q.call!("CREATE TABLE IF NOT EXISTS animals (name text PRIMARY KEY, legs tinyint, friendly boolean);")
|> Q.call!( base |> Q.merge(%{ name: "cat", friendly: false }) )
|> Q.call!( base |> Q.put(:name, "dog") )
|> Q.call!( base |> Q.merge(%{ name: "bonobo", legs: 2 }) )
|> Q.call!("SELECT * FROM animals;")
|> Stream.chunk(2)
animals_by_pair
|> Enum.at(0)
# => [ %{name: "cat", legs: 4, friendly: false}, %{name: "dog", legs: 4, friendly: true} ]
animals_by_pair
|> Enum.to_list
# => [
# [ %{name: "cat", legs: 4, friendly: false}, %{name: "dog", legs: 4, friendly: true} ],
# [ %{name: "bonobo", legs: 2, friendly: true} ]
# ]Use comprehensions on the results of a CQL query
for %{ legs: leg_count, name: name, friendly: true } <- Q.call!(client, "SELECT * FROM animals"),
leg_count == 4,
do: "#{name} has four legs"
# => [ "dog has four legs" ]If you want different clusters, in your project's config/config.exs:
use Mix.Config
config :cqerl,
cassandra_clusters: [
cluster1: { [{"10.0.0.1", 9042}, {"10.0.0.2", 9042}], [keyspace: "keyspace1"] },
cluster2: { [{"10.0.0.1", 9042}, {"10.0.0.2", 9042}], [keyspace: "keyspace2"] }
]Then, in your code
client = CQEx.Client.new! :cluster1
# etc
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