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<h1>Setting Default Values in ActiveRecord with Rails</h1>
<p>When working with databases in web development, it's crucial to have a solid understanding of how data is handled and stored. In the world of Ruby on Rails, ActiveRecord is a powerful tool that simplifies the process of interacting with databases. One of the key features of ActiveRecord is the ability to set default values for columns in your database tables. In this article, we will explore how to use this feature in Rails and why it can be useful in your applications.</p>
<h2>Understanding ActiveRecord and Database Migrations</h2>
<p>Before we dive into setting default values, let's first understand how ActiveRecord and database migrations work in Rails. ActiveRecord is an object-relational mapping (ORM) library that allows developers to interact with databases using object-oriented programming techniques. It is responsible for mapping database tables to Ruby objects and handling the CRUD (create, read, update, delete) operations.</p>
<p>Database migrations, on the other hand, are used to manage changes to your database schema. They allow you to create and modify database tables, columns, and indexes. Migrations are written in Ruby and can be easily version-controlled, making it easy to track and roll back changes to your database.</p>
<h2>Setting Default Values in ActiveRecord</h2>
<p>Now that we have a basic understanding of ActiveRecord and database migrations, let's see how we can set default values for our columns. In Rails, default values can be set in a migration by using the <code>default</code> option when creating a new column. For example, let's say we have a <code>users</code> table with a <code>role</code> column that specifies the user's role in our application. We can set the default value for this column to <code>member</code> by writing the following in our migration:</p>
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<code>add_column :users, :role, :string, default: 'member'</code>
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<p>This will ensure that every new record in the <code>users</code> table will have a <code>role</code> of <code>member</code> unless specified otherwise. This is especially useful when your application has a limited number of roles and you want to avoid having null values in this column.</p>
<h2>Overriding Default Values</h2>
<p>While setting default values can be useful, there may be cases where you want to override the default value for a specific record. In Rails, this can be easily done by passing a value to the <code>create</code> or <code>new</code> method when creating a new record. For example:</p>
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<code>user = User.create(name: 'John', role: 'admin')</code>
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<p>This will create a new <code>User</code> record with the name <code>John</code> and a role of <code>admin</code>, overriding the default value of <code>member</code>.</p>
