Add Get Readable Errors From Schema Parse as a Zod 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).
 
-_1381 TILs and counting..._
+_1382 TILs and counting..._
 
 ---
 
@@ -1639,6 +1639,7 @@ _1381 TILs and counting..._
 - [Check If An Object Is Empty With Zod](zod/check-if-an-object-is-empty-with-zod.md)
 - [Create A Schema That Matches On Any Object](zod/create-a-schema-that-matches-on-any-object.md)
 - [Create Union Type Of Nearly Identical Objects](zod/create-union-type-of-nearly-identical-objects.md)
+- [Get Readable Errors From Schema Parse](zod/get-readable-errors-from-schema-parse.md)
 - [Incorporate Existing Type Into Zod Schema](zod/incorporate-existing-type-into-zod-schema.md)
 - [Set Custom Error Message For Nonempty Array](zod/set-custom-error-message-for-nonempty-array.md)
 

zod/get-readable-errors-from-schema-parse.md

@@ -0,0 +1,52 @@
+# Get Readable Errors From Schema Parse
+
+Let's say we have the following schema for validating the data used to create a
+new post record:
+
+```typescript
+const NewPostSchema = z.object({
+  title: z.string().min(1, "Title is required"),
+  slug: z.string().min(1, "Slug is required"),
+  markdown: z.string().min(1, "Markdown is required"),
+});
+```
+
+When we (safe) parse some incoming user input with that schema and, for
+example, one of the fields is empty, then the validation will fail and we'll
+get some errors.
+
+```typescript
+const result = NewPostSchema.safeParse(userInput)
+
+if(!result.success) {
+  result.error;
+  // ZodError: [
+  //   {
+  //     "code": "too_small",
+  //     "minimum": 1,
+  //     "type": "string",
+  //     "inclusive": true,
+  //     "exact": false,
+  //     "message": "Slug is required",
+  //     "path": [
+  //       "slug"
+  //     ]
+  //   }
+  // ]
+}
+```
+
+That packs a lot of information. But if we are just trying to get something
+minimal and actionable we can show to a user, we might want to flatten the
+errors:
+
+```typescript
+const result = NewPostSchema.safeParse(userInput)
+
+if(!result.success) {
+  result.error.flatten().fieldErrors;
+  // { slug: [ 'Slug is required' ] }
+}
+```
+
+[source](https://github.com/colinhacks/zod/blob/master/ERROR_HANDLING.md#flattening-errors)