nim-codex/codex/stores/queryiterhelper.nim

67 lines
2.0 KiB
Nim

import pkg/questionable
import pkg/questionable/results
import pkg/chronos
import pkg/chronicles
import pkg/datastore/typedds
import ../utils/asynciter
type KeyVal[T] = tuple[key: Key, value: T]
proc toAsyncIter*[T](
queryIter: QueryIter[T],
finishOnErr: bool = true
): Future[?!AsyncIter[?!QueryResponse[T]]] {.async.} =
## Converts `QueryIter[T]` to `AsyncIter[?!QueryResponse[T]]` and automatically
## runs dispose whenever `QueryIter` finishes or whenever an error occurs (only
## if the flag finishOnErr is set to true)
##
if queryIter.finished:
trace "Disposing iterator"
if error =? (await queryIter.dispose()).errorOption:
return failure(error)
return success(AsyncIter[?!QueryResponse[T]].empty())
var errOccurred = false
proc genNext: Future[?!QueryResponse[T]] {.async.} =
let queryResOrErr = await queryIter.next()
if queryResOrErr.isErr:
errOccurred = true
if queryIter.finished or (errOccurred and finishOnErr):
trace "Disposing iterator"
if error =? (await queryIter.dispose()).errorOption:
return failure(error)
return queryResOrErr
proc isFinished(): bool =
queryIter.finished or (errOccurred and finishOnErr)
AsyncIter[?!QueryResponse[T]].new(genNext, isFinished).success
proc filterSuccess*[T](
iter: AsyncIter[?!QueryResponse[T]]
): Future[AsyncIter[tuple[key: Key, value: T]]] {.async.} =
## Filters out any items that are not success
proc mapping(resOrErr: ?!QueryResponse[T]): Future[?KeyVal[T]] {.async.} =
without res =? resOrErr, error:
error "Error occurred when getting QueryResponse", msg = error.msg
return KeyVal[T].none
without key =? res.key:
warn "No key for a QueryResponse"
return KeyVal[T].none
without value =? res.value, error:
error "Error occurred when getting a value from QueryResponse", msg = error.msg
return KeyVal[T].none
(key: key, value: value).some
await mapFilter[?!QueryResponse[T], KeyVal[T]](iter, mapping)