Before we can implement an editing experience, we need to set up an authentication experience. To do this, we'll be running through setting up credentials through Strapi.

Using Next.js Preview Mode

If we're authenticated, we're going to display the pages to the user using Next.js' Preview Mode and display an editing interface to the user.

First, we're going to create two API's: one to set previewData when we're authenticated, and one to clear previewData when we want to unauthenticate.

Create a file called pages/api/preview.js and give it the following content.

pages/api/preview.js

import { STRAPI_JWT } from 'react-tinacms-strapi'
const previewHandler = (req, res) => {
  const previewData = {
    strapi_jwt: req.cookies[STRAPI_JWT],
  }

  res.setPreviewData(previewData)
  res.status(200).end()
}

export default previewHandler

Upon authenticating, Strapi will pass us a JWT. We store this JWT in previewData from where we will pull it anytime we want to call a Strapi API.

Create another file called pages/api/reset-preview.ts and give it the following content.

pages/api/reset-preview.js

export default (_req, res) => {
  res.clearPreviewData()
  res.status(200).end()
}

Whenever we call this API, we will clear the preview data, and the user will become unauthenticated.

Modify Strapi's Authenticated Role

In the previous step you gave Public users read-access. Now we want to give edit access to Authenticated users. Head back to Roles & Permissions in Strapi and click on the Authenticated role.

To keep things simple, we'll give Authenticated users full permissions on Authors and Blog Posts. Click Select All on both of these types and click Save.

Additionally we want these users to be able to upload images to use as a coverImage. Click on the UPLOAD header on this page and give the role the upload permission. Again, click Save.

While we're here, let's also set up a user with the Authenticated role. Head over to Users->Add New User. Give them a Username, Email, Password, and set the Confirmed toggle to "ON". Give them the Authenticated role and then hit the Save button.

Setup a Simple Authentication Interface

Head into pages/_app.js. We're going to add a button to our pages that will pop-up a window asking for authentication and then put us into preview mode if everything goes well.

First we'll enable or disable Tina based on whether we're in preview mode.

pages/_app.js

  const cms = useMemo(() => new TinaCMS({
-   toolbar: true,
-   enabled: true,
+   toolbar: pageProps.preview,
+   enabled: pageProps.preview,
    apis: {
      strapi: new StrapiClient(process.env.STRAPI_URL),
    },
    media: new StrapiMediaStore(process.env.STRAPI_URL),
  }), []);

Next, we need to create functions that let our Strapi provider know what we want to do when authenticating/unauthenticating. Add the following two methods to the bottom of _app.js.

pages/_app.js

const enterEditMode = () => {
  return fetch(`/api/preview`).then(() => {
    window.location.href = window.location.pathname
  })
}

const exitEditMode = () => {
  return fetch(`/api/reset-preview`).then(() => {
    window.location.reload()
  })
}

Pass these two functions into the Strapi provider, and give Strapi knowledge of whether or not we're in preview mode.

pages/_app.js

      <StrapiProvider
-       onLogin={() => {
-         /* we'll come back to this */
-       }}
-       onLogout={() => {
-         /* we'll come back to this */
-       }}}
+       onLogin={enterEditMode}
+       onLogout={exitEditMode}
      >
        <Component {...pageProps} />
      </StrapiProvider>

Now the Strapi provider knows to call our two API functions whenever authentication is successful.

Finally, we'll go ahead and actually create a button that will let us enter/exit editing mode. Create a new component:

pages/_app.js

import { useCMS } from '@tinacms/react-core'

// ...

export const EditButton = () => {
  const cms = useCMS()
  return (
    <button onClick={() => (cms.enabled ? cms.disable() : cms.enable())}>
      {cms.enabled ? `Stop Editing ` : `Edit this Site `}
    </button>
  )
}

For simplicity, we'll just have that button be displayed at the top of every page.

pages/_app.js

  return (
    <TinaProvider cms={cms}>
      <StrapiProvider
        onLogin={enterEditMode}
        onLogout={exitEditMode}
      >
+       <EditButton />
        <Component {...pageProps} />
      </StrapiProvider>
    </TinaProvider>
  );

Now go into our index page and make a quick change to getStaticProps. Change the signature so that it accepts a preview flag and so that we'll have access to previewData.

pages/index.js

- export async function getStaticProps() {
+ export async function getStaticProps({ params, preview, previewData }) {

  // ...

+ if (preview) {
+   return {
+     props: { allPosts: postResults.data.blogPosts, preview, ...previewData },
+   };
+ }

  return {
-    props: { allPosts: postResults.data.blogPosts },
+    props: { allPosts: postResults.data.blogPosts, preview: false },
  };

Now refresh the index page and should see a link that says "Edit This Site". Clicking on it will bring up a login screen. Log in with the credentials you created earlier. You should see the Tina toolbar appear and the link should change to "Stop Editing".

We also need our blog post pages to use preview and previewData. So exactly as we did for the index, go into [slug].js and add in the following

pages/posts/[slug.js]

- export async function getStaticProps({ params }) {
+ export async function getStaticProps({ params, preview, previewData }) {

  // ...
+ if (preview) {
+   return {
+     props: {
+       post: {
+         ...post,
+         content
+       },
+       preview,
+       ...previewData,
+     },
+   };
+ }

  return {
    props: {
      post: {
        ...post,
        content,
      },
+     preview: false,
    },
  };

With this taken care of, we can move onto adding an editing experience to our blog posts.