add form validation

dashboard-app-course/app/lib/actions.ts

@@ -9,21 +9,42 @@ const sql = postgres(process.env.POSTGRES_URL!, {ssl: 'require'});
 
 const FormSchema = z.object({
     id: z.string(),
-    customerId: z.string(),
-    amount: z.coerce.number(),
-    status: z.enum(['pending', 'paid']),
+    customerId: z.string({
+        invalid_type_error: 'Please select a customer.',
+    }),
+    amount: z.coerce.number().gt(0, { message: 'Please enter an amount greater than $0.'}),
+    status: z.enum(['pending', 'paid'], {
+        invalid_type_error: 'Please select an invoice status.',
+    }),
     date: z.string(),
 });
 
 const CreateInvoice = FormSchema.omit({id: true, date: true});
 
-export async function createInvoice(formData: FormData){
-    const { customerId, amount, status } = CreateInvoice.parse({
+export type State = {
+    errors?: {
+        customerId?: string[];
+        amount?: string[];
+        status?: string[];
+    };
+    message?: string | null;
+};
+
+export async function createInvoice(prevState: State, formData: FormData){
+    const validateFields = CreateInvoice.safeParse({
         customerId: formData.get('customerId'),
         amount: formData.get('amount'),
         status: formData.get('status'),
     });
 
+    if(!validateFields.success){
+        return{
+            errors: validateFields.error.flatten().fieldErrors,
+            message: 'Missing fields. Failed to create invoice.',
+        }
+    }
+
+    const { customerId, amount, status } = validateFields.data;
     const amountInCents = amount * 100;
     const date = new Date().toISOString().split('T')[0];