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crud.md

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CRUD

Create

Combination of object creation and insertion into database.

Post.create(name: "Granite Rocks!", body: "Check this out.") # Set attributes and call save
Post.create!(name: "Granite Rocks!", body: "Check this out.") # Set attributes and call save!. Will throw an exception when the save failed

To create a record without setting the created_at & updated_at fields, you can pass in skip_timestamps.

Post.create({name: "Granite Rocks!", body: "Check this out."}, skip_timestamps: true)

Insert

Inserts an already created object into the database.

post = Post.new
post.name = "Granite Rocks!"
post.body = "Check this out."
post.save

post = Post.new
post.name = "Granite Rocks!"
post.body = "Check this out."
post.save! # raises when save failed

To skip the validation callbacks, pass in validate: false:

post.save(validate: false)
post.save!(validate: false)

You can also pass in skip_timestamps to save without changing the updated_at field on update:

post.save(skip_timestamps: true)
post.save!(skip_timestamps: true)

Read

find

Finds the record with the given primary key.

post = Post.find 1
if post
  puts post.name
end

post = Post.find! 1 # raises when no records found

find_by

Finds the record(s) that match the given criteria

post = Post.find_by(slug: "example_slug")
if post
  puts post.name
end

post = Post.find_by!(slug: "foo") # raises when no records found.
other_post = Post.find_by(slug: "foo", type: "bar") # Also works for multiple arguments.

first

Returns the first record.

post = Post.first
if post
  puts post.name
end

post = Post.first! # raises when no records exist

reload

Returns the record with the attributes reloaded from the database.

Note: this method is only defined when the Spec module is present.

post = Post.create(name: "Granite Rocks!", body: "Check this out.")
# record gets updated by another process
post.reload # performs another find to fetch the record again

where, order, limit, offset, group_by

See querying for more details of using the QueryBuilder.

all

Returns all records of a model.

posts = Post.all
if posts
  posts.each do |post|
    puts post.name
  end
end

See querying for more details on using all

Update

Updates a given record already saved in the database.

post = Post.find 1
post.name = "Granite Really Rocks!"
post.save

post = Post.find 1
post.update(name: "Granite Really Rocks!") # Assigns attributes and calls save

post = Post.find 1
post.update!(name: "Granite Really Rocks!") # Assigns attributes and calls save!. Will throw an exception when the save failed

To update a record without changing the updated_at field, you can pass in skip_timestamps:

post = Post.find 1
post.update({name: "Granite Really Rocks!"}, skip_timestamps: true)
post.update!({name: "Granite Really Rocks!"}, skip_timestamps: true)

Delete

Delete a specific record.

post = Post.find 1
post.destroy if post
puts "deleted" if post.destroyed?

post = Post.find 1
post.destroy! # raises when delete failed

Clear all records of a model

Post.clear #truncate the table