add ash_tutorial
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ash_tutorial/querying.livemd
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ash_tutorial/querying.livemd
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# Ash: 3 - Querying
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```elixir
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Application.put_env(:ash, :validate_domain_resource_inclusion?, false)
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Application.put_env(:ash, :validate_domain_config_inclusion?, false)
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Mix.install([{:ash, "~> 3.0"}], consolidate_protocols: false)
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```
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## But First, Data Persistence
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<div class="flex items-center w-full flex-start justify-between rounded-xl p-4" style="background-color: #f0f5f9; color: #61758a;">
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<div class="flex">
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<i class="ri-arrow-left-fill"></i>
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<a class="flex ml-2" style="color: #61758a;" href="actions.livemd">Actions</a>
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</div>
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<div class="flex">
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<i class="ri-home-fill"></i>
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<a class="flex ml-2" style="color: #61758a;" href="overview.livemd">Home</a>
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</div>
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<div class="flex">
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<a class="flex mr-2" style="color: #61758a;" href="attributes.livemd">Attributes</a>
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<i class="ri-arrow-right-fill"></i>
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</div>
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</div>
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<!-- livebook:{"break_markdown":true} -->
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So far we have just created changesets, but we have not actually created any instances of a resource, also known as records. Before we can play around with querying, we need to add a data layer. It is much more common to use [Postgres](https://github.com/ash-project/ash_postgres) in production, but we will use [ETS data layer](https://hexdocs.pm/ash/dsl-ash-datalayer-ets.html#ets) for the remainder of this tutorial to keep dependencies to a minimum.
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<!-- livebook:{"force_markdown":true} -->
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```elixir
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use Ash.Resource,
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domain: YourDomain,
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data_layer: Ash.DataLayer.Ets
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```
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## In this tutorial you will do basic Query and CRUD operations
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But first you need to enable all basic **CRUD** operations.
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Do this by adding default `:read` and `:destroy` actions, as well as `:create` and `:update` actions that accept `[:name]`.
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<details class="rounded-lg my-4" style="background-color: #96ef86; color: #040604;">
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<summary class="cursor-pointer font-bold p-4"></i>Show Solution</summary>
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<div class="p-4">
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```elixir
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defmodule Tutorial.Profile do
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use Ash.Resource,
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domain: Tutorial,
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data_layer: Ash.DataLayer.Ets
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actions do
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defaults [:read, :destroy]
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create :create do
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accept [:name]
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end
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update :update do
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accept [:name]
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end
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end
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attributes do
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uuid_primary_key :id
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attribute :name, :string
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end
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end
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defmodule Tutorial do
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use Ash.Domain
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resources do
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resource Tutorial.Profile
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end
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end
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```
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</div>
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</details>
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### Enter your solution
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```elixir
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defmodule Tutorial.Profile do
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use Ash.Resource,
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domain: Tutorial,
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data_layer: Ash.DataLayer.Ets
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actions do
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# <--- Create your actions here
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end
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attributes do
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uuid_primary_key :id
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attribute :name, :string
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end
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end
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defmodule Tutorial do
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use Ash.Domain
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resources do
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resource Tutorial.Profile
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end
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end
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```
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## Creating
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Add 2 Profiles to the database.
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* One with the name "Joe Armstrong"
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* One with your name
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You can create a `Profile` by:
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* Creating a Changeset with `Ash.Changeset.for_create(Tutorial.Profile, :create, %{name: "Your Name"})`,
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* Then giving the changeset to `Ash.create!()`.
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*Hint: Use a pipeline*
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<details class="rounded-lg my-4" style="background-color: #96ef86; color: #040604;">
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<summary class="cursor-pointer font-bold p-4"></i>Show Solution</summary>
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<div class="p-4">
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```elixir
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Tutorial.Profile
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|> Ash.Changeset.for_create(:create, %{name: "The Name"})
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|> Ash.create!()
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```
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</div>
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</details>
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**Enter your solution**
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```elixir
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```
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## Reading
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Now, read all the generated Profiles.
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Call `Ash.read!/1` with the `Tutorial.Profile` module.
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<details class="rounded-lg my-4" style="background-color: #96ef86; color: #040604;">
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<summary class="cursor-pointer font-bold p-4"></i>Show Solution</summary>
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<div class="p-4">
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```elixir
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Tutorial.Profile
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|> Ash.read!()
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```
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</div>
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</details>
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**Enter your solution**
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```elixir
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```
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Now fetch the "Joe Armstrong" Profile.
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You can achieve this by introducing a filter.
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First you'll need to `require Ash.Query`
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Then call `Ash.Query.filter(name == "Joe Armstrong")` with the `Tutorial.Profile`.
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Put the result into the `joe` variable. `Ash.read!/1` returns a list, so make sure to extract the single returned value out of that list.
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<details class="rounded-lg my-4" style="background-color: #96ef86; color: #040604;">
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<summary class="cursor-pointer font-bold p-4"></i>Show Solution</summary>
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<div class="p-4">
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```elixir
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require Ash.Query
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[joe] =
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Tutorial.Profile
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|> Ash.Query.filter(name == "Joe Armstrong")
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|> Ash.read!()
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```
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</div>
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</details>
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**Enter your solution**
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```elixir
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```
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You'll use the `joe` variable in the next sections.
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## Updating
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Now change `Joe Armstrong`'s name to `Neil Armstrong`.
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You can do this by providing the `Ash.Changeset.for_update/3` with:
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* the resource you want to change, in this case `joe`
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* the `:update` atom
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* a map of the values you want to change, in this case `%{name: "Neil Armstrong"}`
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Then apply the changeset by calling `Ash.update!/1` with the changeset.
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*Hint: Using a pipeline might be a good idea.*
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<details class="rounded-lg my-4" style="background-color: #96ef86; color: #040604;">
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<summary class="cursor-pointer font-bold p-4"></i>Show Solution</summary>
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<div class="p-4">
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```elixir
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joe
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|> Ash.Changeset.for_update(:update, %{name: "Neil Armstrong"})
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|> Ash.update!()
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```
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</div>
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</details>
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**Enter your solution**
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```elixir
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```
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## Destroying
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Finally, remove `joe` from the database.
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Do this using the `Ash.destroy!/1` function.
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<details class="rounded-lg my-4" style="background-color: #96ef86; color: #040604;">
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<summary class="cursor-pointer font-bold p-4"></i>Show Solution</summary>
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<div class="p-4">
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```elixir
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Ash.destroy!(joe)
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```
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</div>
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</details>
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**Enter your solution**
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```elixir
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```
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<div class="flex items-center w-full flex-start justify-between rounded-xl p-4" style="background-color: #f0f5f9; color: #61758a;">
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<div class="flex">
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||||
<i class="ri-arrow-left-fill"></i>
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<a class="flex ml-2" style="color: #61758a;" href="actions.livemd">Actions</a>
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</div>
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||||
<div class="flex">
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||||
<i class="ri-home-fill"></i>
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||||
<a class="flex ml-2" style="color: #61758a;" href="overview.livemd">Home</a>
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</div>
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||||
<div class="flex">
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||||
<a class="flex mr-2" style="color: #61758a;" href="attributes.livemd">Attributes</a>
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<i class="ri-arrow-right-fill"></i>
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</div>
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</div>
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