add Collection.findOne

src/Collection.ts

@@ -4,6 +4,7 @@
 import * as Chunk from "effect/Chunk"
 import * as Effect from "effect/Effect"
 import * as F from "effect/Function"
+import * as O from "effect/Option"
 import * as Stream from "effect/Stream"
 import type {
   BulkWriteOptions,
@@ -50,6 +51,32 @@ export const findV2 = <T extends Document = Document>(
     }
   )
 
+export const findOne: {
+  <T extends Document = Document>(
+    filter: Filter<T>,
+    options?: FindOptions
+  ): (
+    collection: Collection<T>
+  ) => Effect.Effect<O.Option<T>, MongoError.MongoError>
+  <T extends Document = Document>(
+    collection: Collection<T>,
+    filter: Filter<T>,
+    options?: FindOptions
+  ): Effect.Effect<O.Option<T>, MongoError.MongoError>
+} = F.dual(
+  (args) => isCollection(args[0]),
+  <T extends Document = Document>(
+    collection: Collection<T>,
+    filter: Filter<T>,
+    options?: FindOptions
+  ): Effect.Effect<O.Option<T>, MongoError.MongoError> =>
+    F.pipe(
+      Effect.promise(() => collection.findOne(filter, options)),
+      Effect.map((value) => O.fromNullable(value)),
+      Effect.catchAllDefect(MongoError.mongoErrorDie<O.Option<T>>("findOne error"))
+    )
+)
+
 export const insertOne: {
   <T extends Document = Document>(
     doc: OptionalUnlessRequiredId<T>,

test/Collection.test.ts

@@ -2,6 +2,7 @@ import * as Collection from "@doubleloop-io/effect-mongodb/Collection"
 import * as Db from "@doubleloop-io/effect-mongodb/Db"
 import * as FindCursor from "@doubleloop-io/effect-mongodb/FindCursor"
 import * as Effect from "effect/Effect"
+import * as O from "effect/Option"
 import { ObjectId } from "mongodb"
 import { expect, test } from "vitest"
 import { describeMongo } from "./support/describe-mongo.js"
@@ -42,4 +43,38 @@ describeMongo("Collection", (ctx) => {
       { _id: expect.any(ObjectId), name: "NAME_3" }
     ])
   })
+
+  test("find one", async () => {
+    const program = Effect.gen(function*(_) {
+      const db = yield* _(ctx.database)
+      const collection = yield* _(Db.collection(db, "find-one"))
+
+      yield* _(
+        Collection.insertMany(collection, [{ name: "ANY_NAME_1" }, { name: "john" }, { name: "ANY_NAME_2" }])
+      )
+
+      return yield* _(Collection.findOne(collection, { name: "john" }))
+    })
+
+    const result = await Effect.runPromise(program)
+
+    expect(result).toEqual(O.some({ _id: expect.any(ObjectId), name: "john" }))
+  })
+
+  test("find one - no result", async () => {
+    const program = Effect.gen(function*(_) {
+      const db = yield* _(ctx.database)
+      const collection = yield* _(Db.collection(db, "find-one-no-result"))
+
+      yield* _(
+        Collection.insertMany(collection, [{ name: "ANY_NAME_1" }, { name: "ANY_NAME_2" }, { name: "ANY_NAME_2" }])
+      )
+
+      return yield* _(Collection.findOne(collection, { name: "john" }))
+    })
+
+    const result = await Effect.runPromise(program)
+
+    expect(result).toEqual(O.none())
+  })
 })