Serialize the RenderBlogPost to JSON.

This struct still does not contain anything, but I'm just setting up the skeleton for this code.

src/blog_post/convert.rs

@@ -0,0 +1,8 @@
+use super::render_context::RenderBlogPost;
+use super::BlogPost;
+
+pub(crate) fn convert_blog_post_to_render_context(post: &BlogPost) -> RenderBlogPost {
+    RenderBlogPost {
+        id: post.id.clone(),
+    }
+}

src/blog_post/definition.rs

@@ -8,7 +8,7 @@ use crate::error::CustomError;
 
 #[derive(Debug)]
 pub(crate) struct BlogPost {
-    id: String,
+    pub(crate) id: String,
 }
 
 impl BlogPost {

src/blog_post/mod.rs

@@ -1,3 +1,5 @@
+mod convert;
 mod definition;
 mod render_context;
+pub(crate) use convert::convert_blog_post_to_render_context;
 pub(crate) use definition::BlogPost;

src/blog_post/render_context.rs

@@ -4,5 +4,5 @@ use serde::Serialize;
 #[serde(tag = "type")]
 #[serde(rename = "blog_post")]
 pub(crate) struct RenderBlogPost {
-    id: String,
+    pub(crate) id: String,
 }