snapshots!

birdie_snapshots/postgres_snapshot.accepted

@@ -0,0 +1,12 @@
+---
+version: 1.2.5
+title: postgres snapshot
+file: ./test/eventsourcing_postgres_test.gleam
+test_name: postgres_store_store_snapshots_test
+---
+Ok(Some(Snapshot(
+  "92085b42-032c-4d7a-84de-a86d67123858",
+  BankAccount(True, 4.01),
+  3,
+  1737553670,
+)))

birdie_snapshots/postgres_snapshot.new

@@ -0,0 +1,10 @@
+---
+version: 1.2.5
+title: postgres snapshot
+---
+Ok(Some(Snapshot(
+  "92085b42-032c-4d7a-84de-a86d67123858",
+  BankAccount(True, 4.01),
+  3,
+  1737553717,
+)))

gleam.toml

@@ -1,5 +1,5 @@
 name = "eventsourcing_postgres"
-version = "5.0.0"
+version = "5.0.1"
 
 # Fill out these fields if you intend to generate HTML documentation or publish
 # your project to the Hex package manager.
@@ -21,3 +21,4 @@ gleam_json = ">= 2.3.0 and < 3.0.0"
 gleeunit = ">= 1.2.0 and < 2.0.0"
 birdie = ">= 1.2.5 and < 2.0.0"
 pprint = ">= 1.0.4 and < 2.0.0"
+exception = ">= 2.0.0 and < 3.0.0"

manifest.toml

@@ -8,6 +8,7 @@ packages = [
   { name = "birl", version = "1.8.0", build_tools = ["gleam"], requirements = ["gleam_regexp", "gleam_stdlib", "ranger"], otp_app = "birl", source = "hex", outer_checksum = "2AC7BA26F998E3DFADDB657148BD5DDFE966958AD4D6D6957DD0D22E5B56C400" },
   { name = "edit_distance", version = "2.0.1", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "edit_distance", source = "hex", outer_checksum = "A1E485C69A70210223E46E63985FA1008B8B2DDA9848B7897469171B29020C05" },
   { name = "eventsourcing", version = "6.0.0", build_tools = ["gleam"], requirements = ["birl", "gleam_stdlib"], otp_app = "eventsourcing", source = "hex", outer_checksum = "E72DBA6CB88745EC87EAFCBAC1083CF0F1FDDD96CC108276AA867147B313714A" },
+  { name = "exception", version = "2.0.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "exception", source = "hex", outer_checksum = "F5580D584F16A20B7FCDCABF9E9BE9A2C1F6AC4F9176FA6DD0B63E3B20D450AA" },
   { name = "filepath", version = "1.1.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "filepath", source = "hex", outer_checksum = "67A6D15FB39EEB69DD31F8C145BB5A421790581BD6AA14B33D64D5A55DBD6587" },
   { name = "glam", version = "2.0.1", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "glam", source = "hex", outer_checksum = "66EC3BCD632E51EED029678F8DF419659C1E57B1A93D874C5131FE220DFAD2B2" },
   { name = "glance", version = "2.0.0", build_tools = ["gleam"], requirements = ["gleam_stdlib", "glexer"], otp_app = "glance", source = "hex", outer_checksum = "784CE3B5658CF589B2E811031992FDADDFA9C7FD2A51F1140EE019F121D6D0EB" },
@@ -35,6 +36,7 @@ packages = [
 [requirements]
 birdie = { version = ">= 1.2.5 and < 2.0.0" }
 eventsourcing = { version = ">= 6.0.0 and < 7.0.0" }
+exception = { version = ">= 2.0.0 and < 3.0.0" }
 gleam_json = { version = ">= 2.3.0 and < 3.0.0" }
 gleam_stdlib = { version = ">= 0.52.0 and < 2.0.0" }
 gleeunit = { version = ">= 1.2.0 and < 2.0.0" }

src/eventsourcing_postgres.gleam

@@ -62,6 +62,13 @@ const save_snapshot_query = "
     entity = EXCLUDED.entity
   "
 
+const select_snapshot_query = "
+  SELECT aggregate_type, aggregate_id, sequence, entity, timestamp
+  FROM snapshot
+  WHERE aggregate_type = $1 
+    AND aggregate_id = $2
+"
+
 // TYPES ----
 
 type Metadata =
@@ -128,7 +135,41 @@ fn load_snapshot(
   Option(eventsourcing.Snapshot(entity)),
   eventsourcing.EventSourcingError(error),
 ) {
-  Ok(None)
+  let row_decoder = {
+    use aggregate_id <- decode.field(1, decode.string)
+    use sequence <- decode.field(2, decode.int)
+    use entity <- decode.field(3, {
+      use entity_string <- decode.then(decode.string)
+      let assert Ok(entity) =
+        json.parse(entity_string, postgres_store.entity_decoder)
+      decode.success(entity)
+    })
+    use timestamp <- decode.field(4, decode.int)
+
+    decode.success(eventsourcing.Snapshot(
+      aggregate_id: aggregate_id,
+      entity: entity,
+      sequence: sequence,
+      timestamp: timestamp,
+    ))
+  }
+
+  pog.query(select_snapshot_query)
+  |> pog.parameter(pog.text(postgres_store.aggregate_type))
+  |> pog.parameter(pog.text(aggregate_id))
+  |> pog.returning(row_decoder)
+  |> pog.execute(postgres_store.db)
+  |> result.map(fn(response) {
+    case response.rows {
+      [] -> None
+      [snapshot, ..] -> option.Some(snapshot)
+    }
+  })
+  |> result.map_error(fn(error) {
+    eventsourcing.EventStoreError(
+      "Failed to load snapshot: " <> pprint.format(error),
+    )
+  })
 }
 
 fn save_snapshot(

test/eventsourcing_postgres_test.gleam

@@ -2,6 +2,7 @@ import birdie
 import eventsourcing
 import eventsourcing_postgres
 import example_bank_account
+import exception
 import gleam/option
 import gleeunit
 import gleeunit/should
@@ -43,6 +44,10 @@ fn drop_snapshot_table() {
 }
 
 pub fn postgres_store_test() {
+  use <- exception.defer(fn() {
+    drop_event_table()
+    |> should.be_ok
+  })
   let postgres_store = postgres_store()
   let query = fn(_, _) { Nil }
 
@@ -88,11 +93,13 @@ pub fn postgres_store_test() {
   )
   |> pprint.format
   |> birdie.snap(title: "postgres store")
-  drop_event_table()
-  |> should.be_ok
 }
 
 pub fn postgres_store_load_events_test() {
+  use <- exception.defer(fn() {
+    drop_event_table()
+    |> should.be_ok
+  })
   let postgres_store = postgres_store()
   let query = fn(_, _) { Nil }
 
@@ -140,12 +147,16 @@ pub fn postgres_store_load_events_test() {
   )
   |> pprint.format
   |> birdie.snap(title: "postgres store load events")
-
-  drop_event_table()
-  |> should.be_ok
 }
 
 pub fn postgres_store_store_snapshots_test() {
+  use <- exception.defer(fn() {
+    drop_event_table()
+    |> should.be_ok
+    drop_snapshot_table()
+    |> should.be_ok
+  })
+
   let postgres_store = postgres_store()
   let query = fn(_, _) { Nil }
 
@@ -162,7 +173,7 @@ pub fn postgres_store_store_snapshots_test() {
       example_bank_account.apply,
       example_bank_account.BankAccount(opened: False, balance: 0.0),
     )
-    |> eventsourcing.with_snapshots(eventsourcing.SnapshotConfig(2))
+    |> eventsourcing.with_snapshots(eventsourcing.SnapshotConfig(1))
 
   eventsourcing.execute(
     event_sourcing,
@@ -188,14 +199,10 @@ pub fn postgres_store_store_snapshots_test() {
   |> should.be_ok
   |> should.equal(Nil)
 
-  eventsourcing.load_aggregate(
+  eventsourcing.get_latest_snapshot(
     event_sourcing,
     "92085b42-032c-4d7a-84de-a86d67123858",
   )
   |> pprint.format
-  |> birdie.snap(title: "postgres store")
-  drop_event_table()
-  |> should.be_ok
-  drop_snapshot_table()
-  |> should.be_ok
+  |> birdie.snap(title: "postgres snapshot")
 }