In the changeset/2 function above, we define three validations. |> validate_format(:email, validate_inclusion(:age, 18.100) Constraints won't even be checked in case validations failed. As a consequence, validations are always checked before constraints. On the other hand, constraints rely on the database and are always safe. Those validations start with a unsafe_ prefix, such as unsafe_validate_unique/3. Some validations may happen against the database but they are inherently unsafe. The difference between them is that most validations can be executed without a need to interact with the database and, therefore, are always executed before attempting to insert or update the entry in the database. This use case is primarily covered by the cast/4 function.Įcto changesets provide both validations and constraints which are ultimately turned into errors in case something goes wrong. This use case is primarily covered by the change/2 and put_change/3 functions.Įxternal to the application - for example data provided by the user in a form that needs to be type-converted and properly validated. Internal to the application - for example programmatically generated, or coming from other subsystems. External vs internal dataĬhangesets allow working with both kinds of data: Let's discuss some of this extra functionality. The remaining functions in this module, such as validations, constraints, association handling, are about manipulating changesets. The second one is used to change data directly from your application. The first one is used to cast and validate external parameters, such as parameters sent through a form, API, command line, etc. The functions cast/4 and change/2 are the usual entry points for creating changesets. There is an example of working with changesets in the introductory documentation in the Ecto module. Then, create a mix task to handle migrations.Changesets allow filtering, casting, validation and definition of constraints when manipulating structs. It also should delete the schema if tenant is deleted. What I want to do next is automatically issue query for creating postgres schema when new tenant is created. But of course, the above doesn't work because this feature is only in master branch at this point in time. Then the record will be added to the correct table in tenant_1 schema. Ecto.Schema does! iex> changeset = Guard.changeset(%Guard Initially I thought I could update the changeset's _meta_, but Ecto.Changeset does not have _meta_ key. :context - changes the struct meta context.:prefix - changes the struct query prefix.:source - changes the struct query source.Returns a new struct with updated metadata. Then, I found out about Ecto.put_meta/2 after looking through Ecto source code. However, elixir module attribute is resolved at compile time, so you can't change that dynamically during run time. should use postgres schema for tenant-1. When defining a model, you could set module attribute to tell Ecto that this table should be in postgres schema as defined in But for multi-tenancy purpose, needs to be set dynamically - usually from subdomain i.e. Also, there are few things that are still confusing to me. These are the things that I do to actually insert/update records into a correct schema. Then, run migration for your tenant by running mix ecto.migrate -prefix "tenant_1"įire up iex console by running iex -S mix rver. I don't think Ecto has a built-in function to actually create a schema for you. You would also need to create your own schema by issuing CREATE SCHEMA "tenant_1" from psql shell. This assumes the following model in web/models/guard.ex defmodule Tenancy.Guard doīuilds a changeset based on the `struct` and `params`. There is also library called Apartmentex that you could use to do multi-tenancy. What I am trying to do here is to use Postgres schema to achieve multi-tenancy, and of course using Ecto.ĭisclaimer: This is mostly for my personal notes as I try to understand Ecto/Elixir better. With Ecto 2.0, there is support for Postgres schema or multiple databases for MySQL.
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