Query in Ecto embeds_many association - postgresql

Question

Trying to experiment with Ecto embeds_many, and work great, until I need to query on some data in the embedded field.
So I have something like a product that embeds_many categories
schema "products" do
field :code, :string, null: false
embeds_many :categories, Category,
on_replace: :delete,
primary_key: {:id, :binary_id, autogenerate: false}
do
field :name, :string
end
end
def create_changeset(%Product{} = product, attrs) do
product
|> cast(attrs, [:code])
|> cast_embed(:categories, with: &attributes_changeset/2)
end
def attributes_changeset(%{} = product_attribute, attrs) do
product_attribute
|> cast(attrs, [:id, :name])
end
After creating products I end up with something like this in the postgres table
id code categories
1 11 {"{\"id\": \"dress\", \"name\": \"Dress\"},
"{\"id\": \"shirt\", \"name\": \"Shirt\"}}
2 22 {"{\"id\": \"dress\", \"name\": \"Dress\"}}
So now I want to query all products where id == "dress", and of course I would like to get the 2 results above.
I have experimented with something like this:
q = from p in Product, where: fragment("? #> ?", p.categories, '{"id": "dress"}') but transforms the array in integers: operator does not exist: jsonb[] #> integer[] ... WHERE (p0."categories" #> ARRAY[123,34,105,100,34,58,32,34,100,114,101,115,115,34,125])
or that:
q = from p in Product, where: fragment("? #> ?", p.categories, "[{\"id\": \"dress\"}]"), getting malformed array literal: "[{"id": "dress"}]"
What I hoped was something like:
q = from p in Product, where: fragment("? -> 'id' = ?", p.categories, "rochie") but not sure at all if that will work.

Answer 1

Since categories is a jsonb[] here, not a plain json, the operator #> won't work with it directly. You can use ANY and <# to do what you want:
where: fragment("? <# ANY(?)", ~s|{"id": "dress"}|, p.categories)
This will run '{"id": "dress"}' <# ? for each category in the categories array and return true if any of them match.
(~s|"a"| is just a cleaner way of writing "\"a\"".)