add context reference doc (#332)

Co-authored-by: srijan-27 <[email protected]>

Author: Vipul Rawat

docs/navigation.js

@@ -25,10 +25,10 @@ export const navigation = [
             // { title: 'WebSockets', href: '/docs/advanced-guide/websockets' },
         ],
     },
-    // {
-    //     title: 'References',
-    //     links: [
-    //         { title: 'Context', href: '/docs/references/context' },
+    {
+        title: 'References',
+        links: [
+            { title: 'Context', href: '/docs/references/context' },
     //         { title: 'Configuration', href: '/docs/references/configs' },
     //         { title: 'HTTP Service', href: '/docs/references/http-service' },
     //         { title: 'Files', href: '/docs/references/files' },
@@ -39,6 +39,6 @@ export const navigation = [
     //         { title: 'Logs', href: '/docs/references/logs' },
     //         { title: 'Errors', href: '/docs/references/errors' },
     //         { title: 'Swaggger', href: '/docs/references/swagger' },
-    //     ],
-    // },
+        ],
+    },
 ]

docs/references/context/page.md

@@ -0,0 +1,59 @@
+# GoFr Context
+GoFr context is an object injected by the GoFr handler. It contains all the request-specific data, so for each
+request-response cycle a new context is created. The request can be of any type be it an HTTP request, GRPC call or
+a message from Pub-Sub.
+GoFr Context also embeds the **_container_** which maintains all the dependencies like databases, logger, http service clients,
+, metrics manager, etc. This reduces the complexity of the application as users don't have to maintain and keep track of
+all the dependencies by themselves.
+
+GoFr context is an extension of the default go context, providing a wrapper around the request and response providing the
+user access to the dependencies on the go. 
+
+# Usage
+## Reading HTTP requests
+`ctx.Request` can be used to access the underlying request which provides the following methods to access different
+parts of the request.
+- `Context()` - to access the context associated with the incoming request
+    ```go
+    ctx.Request.Context()
+    ```
+- `Param(string)` - to access the query parameters present in the request, it returns the value of the key provided
+  ```go
+  // Example: Request is /configs?key1=value1&key2=value2
+  value := ctx.Request.Param("key1")
+  // value = "value1"
+  ```
+- `PathParam(string)` - to retrieve the path parameters
+  ```go
+  // Consider the path to be /employee/{id}
+  id := ctx.Request.PathParam("id")
+  ```
+- `Bind(interface{})` - to access a decoded format of the request body, the body is mapped to the interface provided 
+  ```go
+  // incoming request body is 
+  // {
+  //    "name" : "trident",
+  //    "category" : "snacks"
+  // }
+  
+  type product struct{
+      Name string `json:"name"`
+      Category string `json:"category"`
+  }
+
+  var p product 
+  ctx.Bind(&p)
+  // the Bind() method will map the incoming request to variable p
+  ```
+- `HostName()` - to access the host name for the incoming request
+  ```go
+  // for example if request is made from xyz.com
+  host := ctx.Request.HostName()
+  // the host would be http://xyz.com
+  // Note: the protocol if not provided in the headers will be set to http by default
+  ``` 
+  
+## Accessing dependencies
+As mentioned earlier, GoFr context embeds the container object which provides the access to 
+all the injected dependencies by the users. Users can access the fields and methods provided 
+by the **_container_**.