rename_column :table, :old_column, :new_column
You'll probably want to create a separate migration to do this. (Rename FixColumnName
as you will.):
script/generate migration FixColumnName
# creates db/migrate/xxxxxxxxxx_fix_column_name.rb
Then edit the migration to do your will:
# db/migrate/xxxxxxxxxx_fix_column_name.rb
class FixColumnName < ActiveRecord::Migration
def self.up
rename_column :table_name, :old_column, :new_column
end
def self.down
# rename back if you need or do something else or do nothing
end
end
For Rails 3.1 use:
While, the up
and down
methods still apply, Rails 3.1 receives a change
method that "knows how to migrate your database and reverse it when the migration is rolled back without the need to write a separate down method".
See "Active Record Migrations" for more information.
rails g migration FixColumnName
class FixColumnName < ActiveRecord::Migration
def change
rename_column :table_name, :old_column, :new_column
end
end
If you happen to have a whole bunch of columns to rename, or something that would have required repeating the table name over and over again:
rename_column :table_name, :old_column1, :new_column1
rename_column :table_name, :old_column2, :new_column2
...
You could use change_table
to keep things a little neater:
class FixColumnNames < ActiveRecord::Migration
def change
change_table :table_name do |t|
t.rename :old_column1, :new_column1
t.rename :old_column2, :new_column2
...
end
end
end
Then just db:migrate
as usual or however you go about your business.
For Rails 4:
While creating a Migration
for renaming a column, Rails 4 generates a change
method instead of up
and down
as mentioned in the above section. The generated change
method is:
$ > rails g migration ChangeColumnName
which will create a migration file similar to:
class ChangeColumnName < ActiveRecord::Migration
def change
rename_column :table_name, :old_column, :new_column
end
end
In react, we have 2 ways to build components: classes and functions.
DOCS
Hooks are a new addition in React 16.8. They let you use state and other React features without writing a class.
Using the State Hook:
import React, { useState } from 'react';
function Example() {
// Declare a new state variable, which we'll call "count"
const [count, setCount] = useState(0);
return (
<div>
<p>You clicked {count} times</p>
<button onClick={() => setCount(count + 1)}>
Click me
</button>
</div>
);
}
Equivalent Class Example:
class Example extends React.Component {
constructor(props) {
super(props);
this.state = {
count: 0
};
}
render() {
return (
<div>
<p>You clicked {this.state.count} times</p>
<button onClick={() => this.setState({ count: this.state.count + 1 })}>
Click me
</button>
</div>
);
}
}
Best Answer
To test that kind of thing you're going to want to use anonymous controllers within RSpec. Relish has a fantastic example here about them.
Be sure to have a look around in other parts of that documentation too. I've learned a lot by just going through the examples they have there.