build-a-ruby-app-with-cockroachdb.md

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Build a Ruby App with CockroachDB and the Ruby pg Driver	Learn how to use CockroachDB from a simple Ruby application with the pg client driver.	true	false

Use pg Use ActiveRecord

This tutorial shows you how build a simple Ruby application with CockroachDB and the Ruby pg driver.

Before you begin

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Step 1. Install the Ruby pg driver

To install the Ruby pg driver, run the following command:

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$ gem install pg

Step 2. Create the maxroach user and bank database

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Step 3. Generate a certificate for the maxroach user

Create a certificate and key for the maxroach user by running the following command. The code samples will run as this user.

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$ cockroach cert create-client maxroach --certs-dir=certs --ca-key=my-safe-directory/ca.key

Step 4. Run the Ruby code

Now that you have a database and a user, you'll run code to create a table and insert some rows, and then you'll run code to read and update values as an atomic transaction.

Basic statements

The following code connects as the maxroach user and executes some basic SQL statements: creating a table, inserting rows, and reading and printing the rows.

Download the basic-sample.rb file, or create the file yourself and copy the code into it.

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{% include {{page.version.version}}/app/basic-sample.rb %}

Then run the code:

{% include copy-clipboard.html %}

$ ruby basic-sample.rb

The output should be:

Initial balances:
id: 1 balance: 1000
id: 2 balance: 250

Transaction (with retry logic)

Next, use the following code to again connect as the maxroach user but this time execute a batch of statements as an atomic transaction to transfer funds from one account to another, where all included statements are either committed or aborted.

Download the txn-sample.rb file, or create the file yourself and copy the code into it.

{% include {{ page.version.version }}/client-transaction-retry.md %}

{% include copy-clipboard.html %}

{% include {{page.version.version}}/app/txn-sample.rb %}

Then run the code:

{% include copy-clipboard.html %}

$ ruby txn-sample.rb

To verify that funds were transferred from one account to another, start the built-in SQL client:

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$ cockroach sql --certs-dir=certs --database=bank

To check the account balances, issue the following statement:

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> SELECT id, balance FROM accounts;

+----+---------+
| id | balance |
+----+---------+
|  1 |     900 |
|  2 |     350 |
+----+---------+
(2 rows)

Step 2. Create the maxroach user and bank database

{% include {{page.version.version}}/app/insecure/create-maxroach-user-and-bank-database.md %}

Step 3. Run the Ruby code

Now that you have a database and a user, you'll run code to create a table and insert some rows, and then you'll run code to read and update values as an atomic transaction.

Basic statements

The following code connects as the maxroach user and executes some basic SQL statements: creating a table, inserting rows, and reading and printing the rows.

Download the basic-sample.rb file, or create the file yourself and copy the code into it.

{% include copy-clipboard.html %}

{% include {{page.version.version}}/app/insecure/basic-sample.rb %}

Then run the code:

{% include copy-clipboard.html %}

$ ruby basic-sample.rb

The output should be:

Initial balances:
id: 1 balance: 1000
id: 2 balance: 250

Transaction (with retry logic)

Next, use the following code to again connect as the maxroach user but this time execute a batch of statements as an atomic transaction to transfer funds from one account to another, where all included statements are either committed or aborted.

Download the txn-sample.rb file, or create the file yourself and copy the code into it.

{% include {{ page.version.version }}/client-transaction-retry.md %}

{% include copy-clipboard.html %}

{% include {{page.version.version}}/app/insecure/txn-sample.rb %}

Then run the code:

{% include copy-clipboard.html %}

$ ruby txn-sample.rb

To verify that funds were transferred from one account to another, start the built-in SQL client:

{% include copy-clipboard.html %}

$ cockroach sql --insecure --database=bank

To check the account balances, issue the following statement:

{% include copy-clipboard.html %}

> SELECT id, balance FROM accounts;

+----+---------+
| id | balance |
+----+---------+
|  1 |     900 |
|  2 |     350 |
+----+---------+
(2 rows)

What's next?

Read more about using the Ruby pg driver.

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