Add a how to add search to your website section

docs/docs/adding-search.md

@@ -0,0 +1,56 @@
+---
+title: "Adding search to your Gatsby website"
+---
+
+Before we go through the steps required to add search to your Gatsby website, it's important to explain the components needed for a searchable website. 
+
+There are three required components:
+
+1. Search index
+2. Search engine
+3. Visual component
+
+Then there are two ways to add search to your site:
+
+1. Use an open source search engine
+2. Use an API-based search engine 
+
+# Site search components
+
+## Search Index
+
+The search index is a copy of your data stored in a search-friendly format. The purpose of storing an index is to optimize speed and performance in finding relevant documents for a search query. Without an index every search would need to scan every page in your site which would quickly become very inefficient.
+
+## Search engine
+
+The search engine takes a search query, runs it through the search index, and returns any matching documents.
+
+## Visual component
+
+The visual component provides an interface to the user, which allows them to write search queries and view the results of each query.
+
+# Adding search to your site
+
+Now that you know the three required components, there are a few ways to approach adding search to your Gatsby-powered site.
+
+## Use an open source search engine
+
+Using an open source search engine is always free and allows you to enable offline search for your site. Note that you need to be careful with offline search because the entire search index has to be brought into the client, which can affect the bundle size significantly.
+
+Open source libraries like [`elesticlunr`](https://www.npmjs.com/package/elasticlunr) or [`js-search`](https://github.com/bvaughn/js-search) can be used to enable search for your site. 
+
+Doing so will require you to create a search index when your site is built. For `elesticlunr`, there is a plugin called [`gatsby-plugin-elasticlunr-search`](https://github.com/andrew-codes/gatsby-plugin-elasticlunr-search) that creates a search index automatically. 
+
+For other libraries, you can use a combination of [`onCreateNode`](https://www.gatsbyjs.org/docs/node-apis/#onCreateNode), [`setFieldsOnGraphQLNodeType`](https://www.gatsbyjs.org/docs/node-apis/#setFieldsOnGraphQLNodeType) and [`sourceNodes`](https://www.gatsbyjs.org/docs/node-apis/#sourceNodes) from the Gatsby node API to create the search index and make it available in GraphQL. For more info on how to do this check out [`gatsby-plugin-elasticlunr-search`'s source code](https://github.com/andrew-codes/gatsby-plugin-elasticlunr-search/blob/master/src/gatsby-node.js#L88-L126).
+
+After building the search index and including it in Gatsby's data layer, you will need to allow the user to search your website. This is typically done by using a text input to capture the search query, then using one of the libraries mentioned above to retrieve the desired document(s).
+
+## Use an API-based search engine 
+
+Using an API-based search engine like Algolia means visitors to your site don't have to download your whole search index (which can become quite large) in order to search your site. The trade-off is that Algolia is a commercial service, so in many cases you'll need to pay to use it.
+
+If you're building a documentation website you can use [Algolia's DocSearch feature](https://community.algolia.com/docsearch/). It will automatically create a search index from the content of your pages.
+
+If your website does not qualify as documentation, you need to collect the search index at build time and upload it using [`gatsby-plugin-algolia`](https://github.com/algolia/gatsby-plugin-algolia).
+
+When using Algolia, they host the search index and search engine for you. Your search queries will be sent to their servers which will respond with any results. You'll need to implement your own visual component; Algolia provides a [React library](https://github.com/algolia/react-instantsearch) which may have components you'd like to use.

www/src/pages/docs/doc-links.yaml

@@ -76,6 +76,8 @@
  link: /docs/adding-a-list-of-markdown-blog-posts/
  - title: Adding Tags and Categories to Blog Posts
  link: /docs/adding-tags-and-categories-to-blog-posts/
+ - title: Adding search to your Gatsby website
+ link: /docs/adding-search/
  - title: Working With Images in Gatsby
  link: /docs/working-with-images/
  - title: Creating Dynamically-Rendered Navigation*