[cms-sanity] Expose the project id to the browser (#14941)

Fixes #14792
Closes #14814

The project id is currently used by Sanity's image builder, which is used in a React component.

@maybac It was faster for me to create a new PR but the credit goes to you, thank you!.

examples/cms-sanity/.env.local.example

@@ -1,3 +1,3 @@
-SANITY_PREVIEW_SECRET=
-SANITY_PROJECT_ID=
-SANITY_API_TOKEN=
+NEXT_PUBLIC_SANITY_PROJECT_ID=
+SANITY_API_TOKEN=
+SANITY_PREVIEW_SECRET=

examples/cms-sanity/README.md

@@ -10,7 +10,7 @@ This example showcases Next.js's [Static Generation](https://nextjs.org/docs/bas
 
 Once you have access to [the environment variables you'll need](#step-4-set-up-environment-variables), deploy the example using [Vercel](https://vercel.com?utm_source=github&utm_medium=readme&utm_campaign=next-example):
 
-[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/import/git?c=1&s=https://github.com/vercel/next.js/tree/canary/examples/cms-sanity&env=SANITY_PREVIEW_SECRET,SANITY_API_TOKEN,SANITY_PROJECT_ID&envDescription=Required%20to%20connect%20the%20app%20with%20Sanity&envLink=https://vercel.link/cms-sanity-env)
+[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/import/git?c=1&s=https://github.com/vercel/next.js/tree/canary/examples/cms-sanity&env=NEXT_PUBLIC_SANITY_PROJECT_ID,SANITY_API_TOKEN,SANITY_PREVIEW_SECRET&envDescription=Required%20to%20connect%20the%20app%20with%20Sanity&envLink=https://vercel.link/cms-sanity-env)
 
 ### Related examples
 
@@ -78,16 +78,16 @@ cp .env.local.example .env.local
 
 Then set each variable on `.env.local`:
 
-- `SANITY_PREVIEW_SECRET` can be any random string (but avoid spaces), like `MY_SECRET` - this is used for [the Preview Mode](https://nextjs.org/docs/advanced-features/preview-mode).
-- `SANITY_PROJECT_ID`: Get the `projectId` value from the `sanity.json` file created in step 2.
-- `SANITY_API_TOKEN`: Copy the API token generated in the previous step.
+- `NEXT_PUBLIC_SANITY_PROJECT_ID` should be the `projectId` value from the `sanity.json` file created in step 2.
+- `SANITY_API_TOKEN` should be the API token generated in the previous step.
+- `SANITY_PREVIEW_SECRET` can be any random string (but avoid spaces), like `MY_SECRET` - this is used for [Preview Mode](https://nextjs.org/docs/advanced-features/preview-mode).
 
 Your `.env.local` file should look like this:
 
 ```bash
-SANITY_PREVIEW_SECRET=...
-SANITY_PROJECT_ID=...
+NEXT_PUBLIC_SANITY_PROJECT_ID=...
 SANITY_API_TOKEN=...
+SANITY_PREVIEW_SECRET=...
 ```
 
 ### Step 5. Prepare project for previewing
@@ -156,7 +156,7 @@ Now, if you go to the post page on localhost, you won't see the updated title. H
 
 To view the preview, go to the post edit page on Sanity, click the three dots above the document and select **Open preview** ([see the instruction here](https://www.sanity.io/docs/preview-content-on-site))
 
-You should now be able to see the updated title. To exit the preview mode, you can click on _"Click here to exit preview mode"_ at the top.
+You should now be able to see the updated title. To exit Preview Mode, you can click on _"Click here to exit preview mode"_ at the top.
 
 ### Step 10. Deploy on Vercel
 
@@ -172,4 +172,4 @@ To deploy your local project to Vercel, push it to GitHub/GitLab/Bitbucket and [
 
 Alternatively, you can deploy using our template by clicking on the Deploy button below.
 
-[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/import/git?c=1&s=https://github.com/vercel/next.js/tree/canary/examples/cms-sanity&env=SANITY_PREVIEW_SECRET,SANITY_API_TOKEN,SANITY_PROJECT_ID&envDescription=Required%20to%20connect%20the%20app%20with%20Sanity&envLink=https://vercel.link/cms-sanity-env)
+[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/import/git?c=1&s=https://github.com/vercel/next.js/tree/canary/examples/cms-sanity&env=NEXT_PUBLIC_SANITY_PROJECT_ID,SANITY_API_TOKEN,SANITY_PREVIEW_SECRET&envDescription=Required%20to%20connect%20the%20app%20with%20Sanity&envLink=https://vercel.link/cms-sanity-env)

examples/cms-sanity/components/cover-image.js

@@ -1,6 +1,6 @@
 import cn from 'classnames'
 import Link from 'next/link'
-import { imageBuilder } from '../lib/api'
+import { imageBuilder } from '../lib/sanity'
 
 export default function CoverImage({ title, url, slug }) {
   const image = (

examples/cms-sanity/lib/api.js

@@ -1,5 +1,4 @@
 import client, { previewClient } from './sanity'
-import sanityImage from '@sanity/image-url'
 
 const getUniquePosts = (posts) => {
   const slugs = new Set()
@@ -25,8 +24,6 @@ const postFields = `
 
 const getClient = (preview) => (preview ? previewClient : client)
 
-export const imageBuilder = sanityImage(client)
-
 export async function getPreviewPostBySlug(slug) {
   const data = await getClient(true).fetch(
     `*[_type == "post" && slug.current == $slug] | order(date desc){

examples/cms-sanity/lib/sanity.js

@@ -1,18 +1,24 @@
 import sanityClient from '@sanity/client'
+import sanityImage from '@sanity/image-url'
 
 const options = {
   // Find your project ID and dataset in `sanity.json` in your studio project
   dataset: 'production',
-  projectId: process.env.SANITY_PROJECT_ID,
+  projectId: process.env.NEXT_PUBLIC_SANITY_PROJECT_ID,
   useCdn: process.env.NODE_ENV === 'production',
   // useCdn == true gives fast, cheap responses using a globally distributed cache.
   // Set this to false if your application require the freshest possible
   // data always (potentially slightly slower and a bit more expensive).
 }
 
-export default sanityClient(options)
+const client = sanityClient(options)
+
+export const imageBuilder = sanityImage(client)
+
 export const previewClient = sanityClient({
   ...options,
   useCdn: false,
   token: process.env.SANITY_API_TOKEN,
 })
+
+export default client