Watch a live product demo 👀 See how Sanity powers richer commerce experiences

Nextjs Landing Pages - TypeScript Error When Checking For Non-Page Types

6 replies
Last updated: Jul 31, 2022
I am changing the sanity-template-nextjs-landing-pages over to TypeScript.
One of the issues that I cannot resolve in my
[[…slug]].tsx
file is this:
When checking for non-page types with
if(!data?._type === 'page')
, I get a TS error
This condition will always return 'false' since the types 'boolean' and 'string' have no overlap.
The value of
_type
is always a string and I’m pretty sure
!foo === 'bar'
is the right syntax?
What’s the issue and how do I resolve it?
Jul 28, 2022, 4:13 AM
Hi
user M
, wonderful that you’re doing that 🙂 I hope you will share the final code with us all!
I will have a look at the issue and get back at you
Jul 28, 2022, 1:46 PM
Until Sanity v3 is closer to an RC (with better TypeScript support), I’m just focusing on the NextJS part of that project.
Jul 28, 2022, 10:58 PM
So you don’t need feedback on this now?
Jul 29, 2022, 6:32 PM
Because I got some TS answers for you :cool_doge:

if (data?._type !== 'page')
:chefs-kiss:
It was a bug in the original code and in ts it would always return
false
because
!data
casts the string to a
boolean
, and
bool === string
will never be true. Removing the
!
will make it so it compares
string
with
string.
Jul 29, 2022, 9:19 PM
Such a simple solution. I never thought of
!==
. That is a simple option and something I could have attempted but never thought of! Thanks so much
user J
!
Jul 30, 2022, 2:46 AM
Our amazing team thought of it... 🙌 And pleasure 🙃
Jul 31, 2022, 9:44 PM

Sanity– build remarkable experiences at scale

The Sanity Composable Content Cloud is the modern headless CMS that treats content as data to power your digital business. Free to get started, and pay-as-you-go on all plans.

Categorized in

Related answers

Get more help in the community Slack

TopicCategoriesFeaturedRepliesLast Updated
After adding the subtitle and running this code npm run graphql-deploy It does nothingSep 15, 2020
how to limit a reference to just one entry in Studio reference input side versus the default as-many-entries-as-you-fill-in-an-array...Sep 18, 2020
Is it possible to fetch more than one "_type" using GROQ?Nov 2, 2020
I want to add a view with the Structure builder (S.view.component) where I list similar documents based on the title. What...Sep 23, 2020
Is there a structure builder example where the format of each preview for the document list is modified?Feb 3, 2021
I have an array of references to a country schema type but it always just returns NULL values for meJan 30, 2021
Hi, I need help with a query for getting the url of an image asset. Here is what I've been trying, but I only get the _ref...Dec 1, 2020
Sanity UI looks brilliant :smiley: Is something like the current date picker possible at the moment? I’m not sure if anicon...Dec 21, 2020
Hey everyone. I have been coding and may have potentially accidentally deleted something. Does anyone know how to resolve...Dec 26, 2020
Hello everyone and happy new year :raised_hands::skin-tone-2:, I have a problem with outputting Portable Text :disappointed:...Jan 1, 2021

Related contributions

Clean Next.js + Sanity app
- Template

Official(made by Sanity team)

A clean example of Next.js with embedded Sanity ready for recomposition.

Cody Olsen
Go to Clean Next.js + Sanity app

Blog with Built-in Content Editing
- Template

Official(made by Sanity team)

A Sanity-powered blog with built-in content editing and instant previews.

Go to Blog with Built-in Content Editing