Add Get Fields For Inserted Row as a Drizzle TIL

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1487 TILs and counting..._
+_1488 TILs and counting..._
 
 ---
 
@@ -212,6 +212,7 @@ _1487 TILs and counting..._
 ### Drizzle
 
 - [Create bigint Identity Column For Primary Key](drizzle/create-bigint-identity-column-for-primary-key.md)
+- [Get Fields For Inserted Row](drizzle/get-fields-for-inserted-row.md)
 
 ### Elixir
 

drizzle/get-fields-for-inserted-row.md

@@ -0,0 +1,56 @@
+# Get Fields For Inserted Row
+
+With Drizzle, we can insert a row with a set of values like so:
+
+```typescript
+await db
+  .insert(todoItems)
+  .values({
+    title,
+    userId,
+    description,
+  })
+```
+
+The result of this is `QueryResult<never>`. In other words, nothing useful is
+coming back to us from the database.
+
+Sometimes an insert is treated as a fire-and-forget (as long as it succeeds) or
+since we know what data we are inserting, we don't need the database to
+response. But what about values that are generated or computed by the database
+-- such as an id from a sequence, timestamp columns that default to `now()`, or
+generated columns.
+
+To get all the fields of a freshly inserted row, we can tack on [the
+`returning()` function](https://orm.drizzle.team/docs/insert#insert-returning)
+(which likely adds something like [`returning
+*`](https://www.postgresql.org/docs/current/dml-returning.html)) to the insert
+query under the hood).
+
+```typescript
+await db
+  .insert(todoItems)
+  .values({
+    title,
+    userId,
+    description,
+  })
+  .returning()
+```
+
+This will have a return type of `Array<type todoItems>` which means that for
+each inserted row we'll have all the fields (columns) for that row.
+
+Alternatively, if we just need the generated ID for the new row(s), we can use
+a partial return like so:
+
+```typescript
+await db
+  .insert(todoItems)
+  .values({
+    title,
+    userId,
+    description,
+  })
+  .returning({ id: todoItems.id })
+```