Step 3 / Select topic Rails Easy

What this bank covers

• Counting rows matching a where hash
• order then first
• pluck returns plain values
• where.not negates a condition
• SQL string condition with a bind placeholder
• sum as a calculation method
• Chaining order, limit and pluck
• Counting with where
• order plus pluck
• has_many collection count
• belongs_to reader
• dependent: :destroy
• has_one and create_profile!
• has_many :through
• belongs_to with class_name
• Scoped has_many ordering
• has_many scopes the collection by foreign key
• dependent: :destroy removes associated records
• has_one returns a single record, not a collection
• before_save can rewrite attributes
• throw :abort cancels the save
• errors are keyed by attribute
• uniqueness validation blocks duplicates
• before_save normalizes attributes
• valid? with a missing required attribute
• Order of create callbacks
• Returning false does not halt the callback chain
• Halting destroy with throw :abort
• Reading a column type from the schema
• Implicit primary key in create_table
• Column defaults reach new objects
• null: false in the schema
• add_column on an existing table
• rename_column changes the schema in place
• references creates a foreign key column
• remove_column drops a column
• The limit option on a string column
• RESTful verbs for resources
• Path helpers from resources
• Default route count for resources
• The edit route pattern
• Recognising a PATCH request
• Nested resource paths
• Limiting routes with :only
• The new route
• Singular and plural helpers
• Extra member routes
• String#pluralize with an irregular noun
• Object#blank? on whitespace
• String#camelize
• Hash#except
• Numeric#megabytes
• Integer#ordinalize
• String#parameterize
• Object#try on nil
• Numeric#week as seconds
• ActiveSupport in_groups_of
• SecureRandom.hex returns twice as many characters as bytes
• ParameterFilter replaces sensitive values with [FILTERED]
• Quoting escapes embedded single quotes by doubling them
• HTML escaping neutralises angle brackets
• secure_compare still reports unequal strings as false
• SHA-256 hex digests are 64 characters
• MessageEncryptor round-trips a payload
• Tampered signed messages raise InvalidSignature
• sanitize_sql_like escapes LIKE wildcards
• fixed_length_secure_compare demands equal lengths
• pluck returns plain column values
• pluck and map return the same values
• find_each yields every record once
• delete_all returns the affected row count
• update_all returns rows changed
• select narrows the loaded attributes
• insert_all writes many rows in one statement
• find_in_batches yields arrays of records
• includes preloads associations to avoid N+1
• any? checks existence cheaply
• Aggregating a filtered relation with sum
• before_validation runs before presence checks
• Reading a column default from the schema
• Strong parameters filtering
• Nested params access
• params.fetch with a default
• Converting a param to a number
• Indifferent access in params
• Permitting array params
• Safe nested lookups with dig
• Handling blank params
• Casting checkbox params to booleans
• Ready jobs in a queue
• Retry attempts exhausted
• Lowest priority number wins
• Preventing duplicate enqueues
• Exponential backoff delays
• Counting queued jobs in a table
• Scheduled jobs that are not due yet
• Dead letter after exhausted retries
• Draining a queue up to worker capacity
• Params values are strings
• Priority ordering in a job queue