How to get all entries by user_id

wernerlaude

In AR this is so simple

@articles = current_user.articles

How to do in Ecto?

def index(conn, _params) do
  current_user = conn.assigns.current_user
  meetings = Listings.list_meetings() #works..sure but I only want current_user ones..

Tried all what I could find in goo, but no success!

#meetings = Repo.get_by!(Meeting, user_id: current_user.id) #nope, but anyway ..is this getting all or only one entry?
=> Enumerable not implemented for

meetings = Repo.all(Meeting) |> where(user_id: current_user.id)
=> MeetingController.init/1 is undefined.

some help would be great..thanks

14 comments

/phoenix #ecto #troubleshooting

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2018-06-03 20:38:54 UTC

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sneako

Repo.all() will run the query you are passing to it, so you will want to compose the full query before passing it in. Your last example is close, try something like Meeting |> where(user_id: current_user.id) |> Repo.all()

Post #1

narand

The Repo.get_by! function retrieves a single match and will throw an error if there are multiple results, see (see Ecto.Repo.get_by!).

Alternatively to using Repo.all: if you have added a has_many field to your User schema, you can also use Ecto.assoc/2 (see Ecto.assoc for examples) to retrieve the meetings.

For a more in-depth discussion, you could always check out the Ecto Association Guide.

Post #2

amnu3387

The Ecto guides are really great.
If you’re loading the user from scratch, and it has a has_many relationship you can also use preload. Like

User
|> preload(:meetings)
|> Repo.get(user_id)

Post #3

wernerlaude

When I do in schema meetings:
field :user_id, :integer
belongs_to :user, Accounts.User

I get: ** (ArgumentError) field/association :user_id is already set on schema..
So what? Do I have to set a relation in schema or not..This is all so unclear ..

Post #4

narand

The field user_id (i.e. the field for the foreign key) will be automatically added when using belongs_to, so you should not add it yourself.

Should you need to customize the foreign key field name (say when you have two associations to the same schema), you can pass the foreign_key option to belongs_to (see belongs_to/3).

Post #5

kokolegorille

It is difficult to change from AR to Ecto, it’s quite different.

But You might find a good free resource here

http://pages.plataformatec.com.br/ebook-whats-new-in-ecto-2-0

And this new book on Ecto

Ecto is closer to sql… here is a simple query

q = from m in Meeting, where: m.user_id == ^current_user.id
Repo.all(q)

Post #6

narand

You can also find an insightful talk of Darin Wilson on YouTube (kinda a preview to the book you mentioned): Thinking in Ecto

Post #7

wernerlaude

Thanks.. finally it works..and thanks for the link..

Post #8

wernerlaude

Yes watched that..and I got the idea.. But still new..

Post #9

peerreynders

You can if you want to:

field :user_id, :id, primary_key: true

and on legacy databases you sometimes have to.

Ecto.Schema.field/3
Ecto.Migration.table/2
Ecto.Migration.add/3

It still won’t teach you SQL - you’re still on your own for that …

We’re also going assume that you’re comfortable working with relational databases and SQL. You don’t need to be an expert, but you should be familiar with tables, columns, indexes and how to write queries. There are many online tutorials that can walk you through the basics.

Post #10

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