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rawman/db_to_stream.ex

Created September 19, 2016 16:49
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db_to_stream.ex
def page(query, from, limit) do
from m in query,
where: m.id > ^from,
limit: ^limit
end
def to_stream(query, repo, page_size \\ 100) do
Stream.resource(
fn -> 0 end,
fn previous_id ->
case get_page(from, page_size, repo) do
[] -> {:halt, []}
items -> {items, List.last(items).id}
end
end,
fn page -> page end
)
end
defp get_page(from, limit, repo) do
query
|> page(from, limit)
|> repo.all
end
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