![]() ![]() Ideally, the specifications defined in the migration should align with your Ecto Schema and generic changeset: defmodule Core. In the migration above we are specifying:ĭepending on your datastore and column type you can apply a variety of data constraints to fulfill your needs. In Elixir, this is commonly achievable through Ecto, the most common component to interact with application data stores, through Ecto Migration DSL: defmodule doĪdd :company_id, references(:companies, type: :binary_id), null: falseĬreate index(:users,, unique: true)Ĭreate constraint(:users, :age_must_be_positive, check: "version > 0") Database Data IntegrityĪs mentioned above, having good database specifications will facilitate data integrity. The Changeset API Pattern is not the sole responsible for achieving this goal, however, once used in conjunction with some data modeling best practices such as column types and constraints, default values and so on, the pattern will become an important application layer on top of an already established data layer, aiming for an overall better data integrity. Overall Goalįacilitate the data integrity main goal, ensure that data is recorded exactly as intended. Data integrity is not to be confused with data security, the discipline of protecting data from unauthorized parties. In short, data integrity aims to prevent unintentional changes to information. The overall intent of any data integrity technique is the same: ensure data is recorded exactly as intended. Data integrity is the maintenance of, and the assurance of the accuracy and consistency of, data over its entire life-cycle, and is a critical aspect to the design, implementation and usage of any system which stores, processes, or retrieves data. One of these patterns that I am having great success while working on web applications in Elixir, is what I am calling, for the lack of a better name, the Changeset API Pattern.īefore I start with the pattern itself, I'd like to outline some information that I consider as the motivation behind the usage, and it is called Data Integrity. Without a database: Ecto.Types can be used to convert stringly-typed data from any source to native Elixir. without inserting to the DB), you can use /1 but be careful: it’s gonna return a struct regardless if the changes was valid or not, so you’ll probably want to validate it explicitly first. Those are called design patterns, formalized best practices that can be used to solve common problems when implementing a system. If youre only using Ecto for schema modules, changeset functions, inserts, and updates, youre missing out on some great features. defmodule do use Ecto. When you want to turn changeset into struct (e.g. Pretty sweet.Over time, as you gain overall experience with software development, you start noticing some paths that can lead to much more smooth sailing. ![]() If there are any errors because of changeset validations the entire batch will be rolled back. new ( ), fn ) – names in a multi operation have to be unique, hence why we’re using the idx as the second element in the tuple to uniquely identify the invite inserts.įinally the whole batch of insert operations gets sent to the ansaction/1 function where it’s executed. So let’s see how we can do this with Ecto.Multi in a fictitious scenario whereby we need to create batches of invites.ĭef create_invites (invite_attrs, user ) do We could of course insert each record one by one and perform our validations via changesets, but then we don’t get the benefits of using a transaction to rollback the entire batch of inserts if something fails. This more direct style of access to the database can be problematic in scenarios where you accept batches of data from the outside world upon which we need to perform validations before we insert it. Of course in Ecto we have the insert_all/3 and update_all/3 functions that are designed for batch inserts and updates respectively, however, both of these do not operate over changesets and are instead designed for more direct operations with the database (they don’t even add timestamps, for instance). One of the most common patterns you may need to perform with Ecto.Multi is operating over many items in a single transaction. Getting to grips with how to perform more complex operations can be difficult to grok at first though. With Ecto.Multi it’s easy for us to write elegant transactional database code.
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