Column types and attributes in Ruby on Rails - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of column types in Rails migrations?

Column types define the kind of data a database column will store, such as strings, integers, or dates. This helps Rails and the database know how to handle and store the data correctly.

beginner

Name three common column types used in Rails migrations.

Common column types include string (for short text), integer (for whole numbers), and boolean (for true/false values).

beginner

What does the null: false attribute do in a Rails migration column?

It ensures that the column cannot have empty (NULL) values. This means every record must have a value for this column.

beginner

How does the default attribute work in Rails migrations?

The default attribute sets a value automatically for the column when a new record is created without specifying that column's value.

beginner

Why would you use the timestamps method in a Rails migration?

It adds two columns, created_at and updated_at, which automatically track when a record is created and last updated.

Which column type is best for storing a user's email address in Rails?

A boolean

B integer

C text

D string

Email addresses are short text, so the string type is appropriate.

What does setting null: false on a column do?

A Sets a default value

B Allows the column to be empty

C Prevents the column from being empty

D Deletes the column

null: false means the column must have a value; it cannot be empty.

Which attribute sets a value automatically if none is provided when creating a record?

A null

B default

C index

D unique

The default attribute sets an automatic value if none is given.

What columns does t.timestamps add in a migration?

A created_at and updated_at

B start_date and end_date

C id and uuid

D name and email

t.timestamps adds created_at and updated_at columns.

Which column type would you use to store true/false values?

A boolean

B integer

C string

D date

Boolean type stores true or false values.

Explain how you would define a column for a user's age that must always have a value and defaults to 18 if not provided.

Think about the type of data, whether it can be empty, and what value to use if none is given.

Describe the purpose of the timestamps method in Rails migrations and why it is useful.

Consider what information about records is important to keep automatically.