Even better leniant parsing

samples/cohost/api/v1/empty_posts_age.json

@@ -0,0 +1 @@
+{"nItems":0,"nPages":0,"items":[],"_links":[{"href":"/api/v1/project/vogon","rel":"project","type":"GET"},{"href":"/api/v1/project/vogon/posts?page=998","rel":"prev","type":"GET"}]}

src/cohost_posts.rs

@@ -1,5 +1,5 @@
 use chrono::{DateTime, Utc};
-use serde::Deserialize;
+use serde::{Deserialize, Deserializer};
 
 pub fn cohost_posts_api_url(project: impl AsRef<str>, page: u64) -> String {
     format!(
@@ -11,7 +11,7 @@ pub fn cohost_posts_api_url(project: impl AsRef<str>, page: u64) -> String {
 
 // Cohost doesn't give us Next links ("rel: next") for further pages, so we'll have to ALWAYS populate the rel=next field
 
-#[derive(Deserialize)]
+#[derive(Debug, Deserialize)]
 pub struct CohostPostsPage {
     #[serde(rename = "nItems")]
     pub number_items: usize,
@@ -22,19 +22,27 @@ pub struct CohostPostsPage {
     pub links: Vec<CohostPostLink>,
 }
 
-#[derive(Deserialize)]
+#[derive(Debug, Deserialize)]
 pub struct CohostPost {
     #[serde(rename = "postId")]
     pub id: u64,
-    #[serde(default)]
+    #[serde(deserialize_with = "deserialize_null_default", default)]
     pub headline: String,
     #[serde(rename = "publishedAt")]
     pub published_at: DateTime<Utc>,
     pub cws: Vec<String>,
     pub tags: Vec<String>,
-    #[serde(rename = "plainTextBody", default)]
+    #[serde(
+        rename = "plainTextBody",
+        deserialize_with = "deserialize_null_default",
+        default
+    )]
     pub plain_body: String,
-    #[serde(rename = "singlePostPageUrl")]
+    #[serde(
+        rename = "singlePostPageUrl",
+        deserialize_with = "deserialize_null_default",
+        default
+    )]
     pub url: String,
     #[serde(rename = "postingProject")]
     pub poster: CohostPostingProject,
@@ -42,31 +50,49 @@ pub struct CohostPost {
     pub share_tree: Vec<CohostPost>,
 }
 
-#[derive(Deserialize)]
+#[derive(Debug, Deserialize)]
 pub struct CohostPostingProject {
     #[serde(rename = "projectId")]
     pub id: u64,
+    #[serde(deserialize_with = "deserialize_null_default", default)]
     pub handle: String,
-    #[serde(rename = "displayName", default)]
+    #[serde(
+        rename = "displayName",
+        deserialize_with = "deserialize_null_default",
+        default
+    )]
     pub display_name: String,
-    #[serde(default)]
+    #[serde(deserialize_with = "deserialize_null_default", default)]
     pub dek: String,
-    #[serde(default)]
+    #[serde(deserialize_with = "deserialize_null_default", default)]
     pub description: String,
-    #[serde(default)]
+    #[serde(deserialize_with = "deserialize_null_default", default)]
     pub pronouns: String,
 }
 
-#[derive(Deserialize)]
+#[derive(Debug, Deserialize)]
 pub struct CohostPostLink {
-    #[serde(default)]
+    #[serde(deserialize_with = "deserialize_null_default", default)]
     pub href: String,
-    #[serde(default)]
+    #[serde(deserialize_with = "deserialize_null_default", default)]
     pub rel: String,
-    #[serde(rename = "type", default)]
+    #[serde(
+        rename = "type",
+        deserialize_with = "deserialize_null_default",
+        default
+    )]
     pub t_type: String,
 }
 
+fn deserialize_null_default<'de, D, T>(deserializer: D) -> Result<T, D::Error>
+where
+    T: Default + Deserialize<'de>,
+    D: Deserializer<'de>,
+{
+    let opt = Option::deserialize(deserializer)?;
+    Ok(opt.unwrap_or_default())
+}
+
 #[test]
 fn test_deserialize() -> Result<(), Box<dyn std::error::Error>> {
     let post_page_json = include_str!("../samples/cohost/api/v1/project_posts.json");
@@ -77,3 +103,19 @@ fn test_deserialize() -> Result<(), Box<dyn std::error::Error>> {
     assert_eq!(post.poster.id, 32693);
     Ok(())
 }
+
+#[test]
+fn test_deserialize_weird() -> Result<(), Box<dyn std::error::Error>> {
+    let post_page_json = include_str!("../samples/cohost/api/v1/vogon_pathological.json");
+    let _post_page_actual: CohostPostsPage = serde_json::from_str(post_page_json)?;
+    Ok(())
+}
+
+#[test]
+fn test_deserialize_empty() -> Result<(), Box<dyn std::error::Error>> {
+    let post_page_json = include_str!("../samples/cohost/api/v1/empty_posts_age.json");
+    let post_page_actual: CohostPostsPage = serde_json::from_str(post_page_json)?;
+    println!("{:?}", post_page_actual);
+    assert!(post_page_actual.items.is_empty());
+    Ok(())
+}