added book details, update, delete. fixes

app/server/graphql/resolvers/bookDeleteResolver.ts

@@ -0,0 +1,22 @@
+import { ensureIdentity } from '@app/server/helpers';
+import { IdentityContext } from '@app/server/identity';
+import { prisma } from '@app/server/prisma/client';
+import { MutationBookDeleteArgs } from '@generated/types';
+
+export async function BookDeleteResolver(
+  _: any,
+  { id }: MutationBookDeleteArgs,
+  { identity }: IdentityContext
+): Promise<void> {
+  ensureIdentity(identity);
+
+  const model = await prisma.book.findUniqueOrThrow({
+    where: { id }
+  });
+
+  if (identity.id !== model.authorId) throw new Error('Operation is not permitted.');
+
+  await prisma.book.delete({
+    where: { id }
+  });
+}