From 1b6ad56edabd9e6979e53a1b6fe55b8cebebdae5 Mon Sep 17 00:00:00 2001
From: Arda TANRIKULU <ardatanrikulu@gmail.com>
Date: Wed, 4 Nov 2020 10:29:45 +0300
Subject: [PATCH 1/3] Fix Learn Sidebar

---
 gatsby-node.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/gatsby-node.js b/gatsby-node.js
index 9f0a7139cb..c6f164fbd4 100644
--- a/gatsby-node.js
+++ b/gatsby-node.js
@@ -148,7 +148,6 @@ exports.createPages = async ({ graphql, actions }) => {
         const { category: definedCategory, next: definedNextPageUrl } = frontmatter
         let category = definedCategory || folder
         if (!currentCategory || category !== currentCategory.name) {
-          currentCategory && categories.push(currentCategory)
           currentCategory = {
             name: category,
             links: [],

From ff651ae71cf751b2fdc87be29e54c6316821a72c Mon Sep 17 00:00:00 2001
From: Arda TANRIKULU <ardatanrikulu@gmail.com>
Date: Wed, 4 Nov 2020 13:25:02 +0300
Subject: [PATCH 2/3] Another attempt

---
 gatsby-node.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gatsby-node.js b/gatsby-node.js
index c6f164fbd4..1ec448e564 100644
--- a/gatsby-node.js
+++ b/gatsby-node.js
@@ -148,6 +148,9 @@ exports.createPages = async ({ graphql, actions }) => {
         const { category: definedCategory, next: definedNextPageUrl } = frontmatter
         let category = definedCategory || folder
         if (!currentCategory || category !== currentCategory.name) {
+          if (currentCategory) {
+            categories.push(currentCategory);
+          }
           currentCategory = {
             name: category,
             links: [],

From 3dfb1ccd4dff44a635e530a623fc010991d35021 Mon Sep 17 00:00:00 2001
From: Arda TANRIKULU <ardatanrikulu@gmail.com>
Date: Wed, 4 Nov 2020 13:47:42 +0300
Subject: [PATCH 3/3] Force deduplication

---
 gatsby-node.js | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/gatsby-node.js b/gatsby-node.js
index 1ec448e564..1f01018018 100644
--- a/gatsby-node.js
+++ b/gatsby-node.js
@@ -138,18 +138,23 @@ exports.createPages = async ({ graphql, actions }) => {
         throw new Error(`First page not found in ${folder}`)
       }
 
-      let categories = []
+      let categoriesMap = {}
       let currentCategory = null
 
       let page = firstPage
       let i = 0
       while (page && i++ < 1000) {
         const { frontmatter } = page
-        const { category: definedCategory, next: definedNextPageUrl } = frontmatter
+        const {
+          category: definedCategory,
+          next: definedNextPageUrl,
+        } = frontmatter
         let category = definedCategory || folder
         if (!currentCategory || category !== currentCategory.name) {
           if (currentCategory) {
-            categories.push(currentCategory);
+            if (!(currentCategory.name in categoriesMap)) {
+              categoriesMap[currentCategory.name] = currentCategory
+            }
           }
           currentCategory = {
             name: category,
@@ -167,9 +172,11 @@ exports.createPages = async ({ graphql, actions }) => {
         }
       }
 
-      categories.push(currentCategory)
+      if (!(currentCategory.name in categoriesMap)) {
+        categoriesMap[currentCategory.name] = currentCategory
+      }
 
-      sideBardata[folder] = categories
+      sideBardata[folder] = Object.values(categoriesMap);
     })
   )