From ec806717db88d22e83679221dff83e2d85f98c49 Mon Sep 17 00:00:00 2001
From: Kirill Vasiltsov <38713361+jlkiri@users.noreply.github.com>
Date: Fri, 10 Apr 2020 21:23:09 +0900
Subject: [PATCH] fix(gatsby-plugin-mdx): Truncate non-latin language excerpts
 correctly (#22638)

* Truncate option for non-latin languages

* Add mention of truncate to docs
---
 packages/gatsby-plugin-mdx/README.md             | 16 ++++++++++++++++
 .../gatsby-plugin-mdx/gatsby/source-nodes.js     | 16 ++++++++++++++--
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/packages/gatsby-plugin-mdx/README.md b/packages/gatsby-plugin-mdx/README.md
index e84135696b459..ebadfca7cec7e 100644
--- a/packages/gatsby-plugin-mdx/README.md
+++ b/packages/gatsby-plugin-mdx/README.md
@@ -562,6 +562,22 @@ export const pageQuery = graphql`
 `
 ```
 
+## Troubleshooting
+
+### Excerpts for non-latin languages
+
+By default, `excerpt` uses `underscore.string/prune` which doesn't handle non-latin characters ([https://github.com/epeli/underscore.string/issues/418](https://github.com/epeli/underscore.string/issues/418)).
+
+If that is the case, you can set `truncate` option on `excerpt` field, like:
+
+```graphql
+{
+  markdownRemark {
+    excerpt(truncate: true)
+  }
+}
+```
+
 ## License
 
 MIT
diff --git a/packages/gatsby-plugin-mdx/gatsby/source-nodes.js b/packages/gatsby-plugin-mdx/gatsby/source-nodes.js
index e22e5dc0a0a6a..04063f32f2a34 100644
--- a/packages/gatsby-plugin-mdx/gatsby/source-nodes.js
+++ b/packages/gatsby-plugin-mdx/gatsby/source-nodes.js
@@ -1,4 +1,5 @@
 const _ = require(`lodash`)
+const { GraphQLBoolean } = require(`gatsby/graphql`)
 const remark = require(`remark`)
 const english = require(`retext-english`)
 const remark2retext = require(`remark-retext`)
@@ -151,8 +152,12 @@ module.exports = (
             type: `Int`,
             defaultValue: 140,
           },
+          truncate: {
+            type: GraphQLBoolean,
+            defaultValue: false,
+          },
         },
-        async resolve(mdxNode, { pruneLength }) {
+        async resolve(mdxNode, { pruneLength, truncate }) {
           if (mdxNode.excerpt) {
             return Promise.resolve(mdxNode.excerpt)
           }
@@ -166,7 +171,14 @@ module.exports = (
             return
           })
 
-          return prune(excerptNodes.join(` `), pruneLength, `…`)
+          if (!truncate) {
+            return prune(excerptNodes.join(` `), pruneLength, `…`)
+          }
+
+          return _.truncate(excerptNodes.join(` `), {
+            length: pruneLength,
+            omission: `…`,
+          })
         },
       },
       headings: {