Rewrite site backend in Rust (#178)

* add shell.nix changes for Rust #176

* set up base crate layout

* add first set of dependencies

* start adding basic app modules

* start html templates

* serve index page

* add contact and feeds pages

* add resume rendering support

* resume cleanups

* get signalboost page working

* rewrite config to be in dhall

* more work

* basic generic post loading

* more tests

* initial blog index support

* fix routing?

* render blogposts

* X-Clacks-Overhead

* split blog handlers into blog.rs

* gallery index

* gallery posts

* fix hashtags

* remove instantpage (it messes up the metrics)

* talk support + prometheus

* Create rust.yml

* Update rust.yml

* Update codeql-analysis.yml

* add jsonfeed library

* jsonfeed support

* rss/atom

* go mod tidy

* atom: add posted date

* rss: add publishing date

* nix: build rust program

* rip out go code

* rip out go templates

* prepare for serving in docker

* create kubernetes deployment

* create automagic deployment

* build docker images on non-master

* more fixes

* fix timestamps

* fix RSS/Atom/JSONFeed validation errors

* add go vanity import redirecting

* templates/header: remove this

* atom feed: fixes

* fix?

* fix??

* fix rust tests

* Update rust.yml

* automatically show snow during the winter

* fix dates

* show commit link in footer

* sitemap support

* fix compiler warning

* start basic patreon client

* integrate kankyo

* fix patreon client

* add patrons page

* remove this

* handle patron errors better

* fix build

* clean up deploy

* sort envvars for deploy

* remove deps.nix

* shell.nix: remove go

* update README

* fix envvars for tests

* nice

* blog: add rewrite in rust post

* blog/site-update: more words

5 files changed, 1252 insertions, 0 deletions

diff --git a/lib/jsonfeed/src/builder.rs b/lib/jsonfeed/src/builder.rs
new file mode 100644
index 0000000..f17740f
--- /dev/null
+++ b/lib/jsonfeed/src/builder.rs
@@ -0,0 +1,204 @@
+use std::default::Default;
+
+use errors::*;
+use feed::{Feed, Author, Attachment};
+use item::{Content, Item};
+
+/// Feed Builder
+///
+/// This is used to programmatically build up a Feed object,
+/// which can be serialized later into a JSON string
+pub struct Builder(Feed);
+
+impl Builder {
+    pub fn new() -> Builder {
+        Builder(Feed::default())
+    }
+
+    pub fn title<I: Into<String>>(mut self, t: I) -> Builder {
+        self.0.title = t.into();
+        self
+    }
+
+    pub fn home_page_url<I: Into<String>>(mut self, url: I) -> Builder {
+        self.0.home_page_url = Some(url.into());
+        self
+    }
+
+    pub fn feed_url<I: Into<String>>(mut self, url: I) -> Builder {
+        self.0.feed_url = Some(url.into());
+        self
+    }
+
+    pub fn description<I: Into<String>>(mut self, desc: I) -> Builder {
+        self.0.description = Some(desc.into());
+        self
+    }
+
+    pub fn user_comment<I: Into<String>>(mut self, cmt: I) -> Builder {
+        self.0.user_comment = Some(cmt.into());
+        self
+    }
+
+    pub fn next_url<I: Into<String>>(mut self, url: I) -> Builder {
+        self.0.next_url = Some(url.into());
+        self
+    }
+
+    pub fn icon<I: Into<String>>(mut self, url: I) -> Builder {
+        self.0.icon = Some(url.into());
+        self
+    }
+
+    pub fn favicon<I: Into<String>>(mut self, url: I) -> Builder {
+        self.0.favicon = Some(url.into());
+        self
+    }
+
+    pub fn author(mut self, author: Author) -> Builder {
+        self.0.author = Some(author);
+        self
+    }
+
+    pub fn expired(mut self) -> Builder {
+        self.0.expired = Some(true);
+        self
+    }
+
+    pub fn item(mut self, item: Item) -> Builder {
+        self.0.items.push(item);
+        self
+    }
+
+    pub fn build(self) -> Feed {
+        self.0
+    }
+}
+
+/// Builder object for an item in a feed
+pub struct ItemBuilder {
+    pub id: Option<String>,
+    pub url: Option<String>,
+    pub external_url: Option<String>,
+    pub title: Option<String>,
+    pub content: Option<Content>,
+    pub summary: Option<String>,
+    pub image: Option<String>,
+    pub banner_image: Option<String>,
+    pub date_published: Option<String>,
+    pub date_modified: Option<String>,
+    pub author: Option<Author>,
+    pub tags: Option<Vec<String>>,
+    pub attachments: Option<Vec<Attachment>>,
+}
+
+impl ItemBuilder {
+    pub fn new() -> ItemBuilder {
+        ItemBuilder {
+            id: None,
+            url: None,
+            external_url: None,
+            title: None,
+            content: None,
+            summary: None,
+            image: None,
+            banner_image: None,
+            date_published: None,
+            date_modified: None,
+            author: None,
+            tags: None,
+            attachments: None,
+        }
+    }
+
+    pub fn title<I: Into<String>>(mut self, i: I) -> ItemBuilder {
+        self.title = Some(i.into());
+        self
+    }
+
+    pub fn image<I: Into<String>>(mut self, i: I) -> ItemBuilder {
+        self.image = Some(i.into());
+        self
+    }
+
+    pub fn id<I: Into<String>>(mut self, i: I) -> ItemBuilder {
+        self.id = Some(i.into());
+        self
+    }
+
+    pub fn url<I: Into<String>>(mut self, i: I) -> ItemBuilder {
+        self.url = Some(i.into());
+        self
+    }
+
+    pub fn external_url<I: Into<String>>(mut self, i: I) -> ItemBuilder {
+        self.external_url = Some(i.into());
+        self
+    }
+
+    pub fn date_modified<I: Into<String>>(mut self, i: I) -> ItemBuilder {
+        self.date_modified = Some(i.into());
+        self
+    }
+
+    pub fn date_published<I: Into<String>>(mut self, i: I) -> ItemBuilder {
+        self.date_published = Some(i.into());
+        self
+    }
+
+    pub fn tags(mut self, tags: Vec<String>) -> ItemBuilder {
+        self.tags = Some(tags);
+        self
+    }
+
+    pub fn author(mut self, who: Author) -> ItemBuilder {
+        self.author = Some(who);
+        self
+    }
+
+    pub fn content_html<I: Into<String>>(mut self, i: I) -> ItemBuilder {
+        match self.content {
+            Some(Content::Text(t)) => {
+                self.content = Some(Content::Both(i.into(), t));
+            },
+            _ => {
+                self.content = Some(Content::Html(i.into()));
+            }
+        }
+        self
+    }
+
+    pub fn content_text<I: Into<String>>(mut self, i: I) -> ItemBuilder {
+        match self.content {
+            Some(Content::Html(s)) => {
+                self.content = Some(Content::Both(s, i.into()));
+            },
+            _ => {
+                self.content = Some(Content::Text(i.into()));
+            },
+        }
+        self
+    }
+
+    pub fn build(self) -> Result<Item> {
+        if self.id.is_none() || self.content.is_none() {
+            return Err("missing field 'id' or 'content_*'".into());
+        }
+        Ok(Item {
+            id: self.id.unwrap(),
+            url: self.url,
+            external_url: self.external_url,
+            title: self.title,
+            content: self.content.unwrap(),
+            summary: self.summary,
+            image: self.image,
+            banner_image: self.banner_image,
+            date_published: self.date_published,
+            date_modified: self.date_modified,
+            author: self.author,
+            tags: self.tags,
+            attachments: self.attachments
+        })
+    }
+}
+
diff --git a/lib/jsonfeed/src/errors.rs b/lib/jsonfeed/src/errors.rs
new file mode 100644
index 0000000..936b7ec
--- /dev/null
+++ b/lib/jsonfeed/src/errors.rs
@@ -0,0 +1,7 @@
+use serde_json;
+error_chain!{
+    foreign_links {
+        Serde(serde_json::Error);
+    }
+}
+
diff --git a/lib/jsonfeed/src/feed.rs b/lib/jsonfeed/src/feed.rs
new file mode 100644
index 0000000..8b5b5ce
--- /dev/null
+++ b/lib/jsonfeed/src/feed.rs
@@ -0,0 +1,296 @@
+use std::default::Default;
+
+use item::Item;
+use builder::Builder;
+
+const VERSION_1: &'static str = "https://jsonfeed.org/version/1";
+
+/// Represents a single feed
+///
+/// # Examples
+///
+/// ```rust
+/// // Serialize a feed object to a JSON string
+///
+/// # extern crate jsonfeed;
+/// # use std::default::Default;
+/// # use jsonfeed::Feed;
+/// # fn main() {
+/// let feed: Feed = Feed::default();
+/// assert_eq!(
+///     jsonfeed::to_string(&feed).unwrap(),
+///     "{\"version\":\"https://jsonfeed.org/version/1\",\"title\":\"\",\"items\":[]}"
+/// );
+/// # }
+/// ```
+///
+/// ```rust
+/// // Deserialize a feed objects from a JSON String
+///
+/// # extern crate jsonfeed;
+/// # use jsonfeed::Feed;
+/// # fn main() {
+/// let json = "{\"version\":\"https://jsonfeed.org/version/1\",\"title\":\"\",\"items\":[]}";
+/// let feed: Feed = jsonfeed::from_str(&json).unwrap();
+/// assert_eq!(
+///     feed,
+///     Feed::default()
+/// );
+/// # }
+/// ```
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct Feed {
+    pub version: String,
+    pub title: String,
+    pub items: Vec<Item>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub home_page_url: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub feed_url: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub user_comment: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub next_url: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub icon: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub favicon: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub author: Option<Author>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub expired: Option<bool>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub hubs: Option<Vec<Hub>>,
+}
+
+impl Feed {
+    /// Used to construct a Feed object
+    pub fn builder() -> Builder {
+        Builder::new()
+    }
+}
+
+impl Default for Feed {
+    fn default() -> Feed {
+        Feed {
+            version: VERSION_1.to_string(),
+            title: "".to_string(),
+            items: vec![],
+            home_page_url: None,
+            feed_url: None,
+            description: None,
+            user_comment: None,
+            next_url: None,
+            icon: None,
+            favicon: None,
+            author: None,
+            expired: None,
+            hubs: None,
+        }
+    }
+}
+
+/// Represents an `attachment` for an item
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct Attachment {
+    url: String,
+    mime_type: String,
+    title: Option<String>,
+    size_in_bytes: Option<u64>,
+    duration_in_seconds: Option<u64>,
+}
+
+/// Represents an `author` in both a feed and a feed item
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct Author {
+    name: Option<String>,
+    url: Option<String>,
+    avatar: Option<String>,
+}
+
+impl Author {
+    pub fn new() -> Author {
+        Author {
+            name: None,
+            url: None,
+            avatar: None,
+        }
+    }
+
+    pub fn name<I: Into<String>>(mut self, name: I) -> Self {
+        self.name = Some(name.into());
+        self
+    }
+
+    pub fn url<I: Into<String>>(mut self, url: I) -> Self {
+        self.url = Some(url.into());
+        self
+    }
+
+    pub fn avatar<I: Into<String>>(mut self, avatar: I) -> Self {
+        self.avatar = Some(avatar.into());
+        self
+    }
+}
+
+/// Represents a `hub` for a feed
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct Hub {
+    #[serde(rename = "type")]
+    type_: String,
+    url: String,
+}
+
+#[cfg(test)]
+mod tests {
+    use serde_json;
+    use std::default::Default;
+    use super::*;
+
+    #[test]
+    fn serialize_feed() {
+        let feed = Feed {
+            version: "https://jsonfeed.org/version/1".to_string(),
+            title: "some title".to_string(),
+            items: vec![],
+            home_page_url: None,
+            description: None,
+            expired: Some(true),
+            ..Default::default()
+        };
+        assert_eq!(
+            serde_json::to_string(&feed).unwrap(),
+            r#"{"version":"https://jsonfeed.org/version/1","title":"some title","items":[],"expired":true}"#
+        );
+    }
+
+    #[test]
+    fn deserialize_feed() {
+        let json = r#"{"version":"https://jsonfeed.org/version/1","title":"some title","items":[]}"#;
+        let feed: Feed = serde_json::from_str(&json).unwrap();
+        let expected = Feed {
+            version: "https://jsonfeed.org/version/1".to_string(),
+             title: "some title".to_string(),
+             items: vec![],
+             ..Default::default()
+        };
+        assert_eq!(
+            feed,
+            expected
+        );
+    }
+
+    #[test]
+    fn serialize_attachment() {
+        let attachment = Attachment {
+            url: "http://example.com".to_string(),
+            mime_type: "application/json".to_string(),
+            title: Some("some title".to_string()),
+            size_in_bytes: Some(1),
+            duration_in_seconds: Some(1),
+        };
+        assert_eq!(
+            serde_json::to_string(&attachment).unwrap(),
+            r#"{"url":"http://example.com","mime_type":"application/json","title":"some title","size_in_bytes":1,"duration_in_seconds":1}"#
+        );
+    }
+
+    #[test]
+    fn deserialize_attachment() {
+        let json = r#"{"url":"http://example.com","mime_type":"application/json","title":"some title","size_in_bytes":1,"duration_in_seconds":1}"#;
+        let attachment: Attachment = serde_json::from_str(&json).unwrap();
+        let expected = Attachment {
+            url: "http://example.com".to_string(),
+            mime_type: "application/json".to_string(),
+            title: Some("some title".to_string()),
+            size_in_bytes: Some(1),
+            duration_in_seconds: Some(1),
+        };
+        assert_eq!(
+            attachment,
+            expected
+        );
+    }
+
+    #[test]
+    fn serialize_author() {
+        let author = Author {
+            name: Some("bob jones".to_string()),
+            url: Some("http://example.com".to_string()),
+            avatar: Some("http://img.com/blah".to_string()),
+        };
+        assert_eq!(
+            serde_json::to_string(&author).unwrap(),
+            r#"{"name":"bob jones","url":"http://example.com","avatar":"http://img.com/blah"}"#
+        );
+    }
+
+    #[test]
+    fn deserialize_author() {
+        let json = r#"{"name":"bob jones","url":"http://example.com","avatar":"http://img.com/blah"}"#;
+        let author: Author = serde_json::from_str(&json).unwrap();
+        let expected = Author {
+            name: Some("bob jones".to_string()),
+            url: Some("http://example.com".to_string()),
+            avatar: Some("http://img.com/blah".to_string()),
+        };
+        assert_eq!(
+            author,
+            expected
+        );
+    }
+
+    #[test]
+    fn serialize_hub() {
+        let hub = Hub {
+            type_: "some-type".to_string(),
+            url: "http://example.com".to_string(),
+        };
+        assert_eq!(
+            serde_json::to_string(&hub).unwrap(),
+            r#"{"type":"some-type","url":"http://example.com"}"#
+        )
+    }
+
+    #[test]
+    fn deserialize_hub() {
+        let json = r#"{"type":"some-type","url":"http://example.com"}"#;
+        let hub: Hub = serde_json::from_str(&json).unwrap();
+        let expected = Hub {
+            type_: "some-type".to_string(),
+            url: "http://example.com".to_string(),
+        };
+        assert_eq!(
+            hub,
+            expected
+        );
+    }
+
+    #[test]
+    fn deser_podcast() {
+        let json = r#"{
+  "version": "https://jsonfeed.org/version/1",
+  "title": "Timetable",
+  "home_page_url": "http://timetable.manton.org/",
+  "items": [
+    {
+      "id": "http://timetable.manton.org/2017/04/episode-45-launch-week/",
+      "url": "http://timetable.manton.org/2017/04/episode-45-launch-week/",
+      "title": "Episode 45: Launch week",
+      "content_html": "I’m rolling out early access to Micro.blog this week. I talk about how the first 2 days have gone, mistakes with TestFlight, and what to do next.",
+      "date_published": "2017-04-26T01:09:45+00:00",
+      "attachments": [
+        {
+          "url": "http://timetable.manton.org/podcast-download/139/episode-45-launch-week.mp3",
+          "mime_type": "audio/mpeg",
+          "size_in_bytes": 5236920
+        }
+      ]
+    }
+  ]
+}"#;
+        serde_json::from_str::<Feed>(&json).expect("Failed to deserialize podcast feed");
+    }
+}
diff --git a/lib/jsonfeed/src/item.rs b/lib/jsonfeed/src/item.rs
new file mode 100644
index 0000000..605525b
--- /dev/null
+++ b/lib/jsonfeed/src/item.rs
@@ -0,0 +1,493 @@
+use std::fmt;
+use std::default::Default;
+
+use feed::{Author, Attachment};
+use builder::ItemBuilder;
+
+use serde::ser::{Serialize, Serializer, SerializeStruct};
+use serde::de::{self, Deserialize, Deserializer, Visitor, MapAccess};
+
+/// Represents the `content_html` and `content_text` attributes of an item
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub enum Content {
+    Html(String),
+    Text(String),
+    Both(String, String),
+}
+
+/// Represents an item in a feed
+#[derive(Debug, Clone, PartialEq)]
+pub struct Item {
+    pub id: String,
+    pub url: Option<String>,
+    pub external_url: Option<String>,
+    pub title: Option<String>,
+    pub content: Content,
+    pub summary: Option<String>,
+    pub image: Option<String>,
+    pub banner_image: Option<String>,
+    pub date_published: Option<String>, // todo DateTime objects?
+    pub date_modified: Option<String>,
+    pub author: Option<Author>,
+    pub tags: Option<Vec<String>>,
+    pub attachments: Option<Vec<Attachment>>,
+}
+
+impl Item {
+    pub fn builder() -> ItemBuilder {
+        ItemBuilder::new()
+    }
+}
+
+impl Default for Item {
+    fn default() -> Item {
+        Item {
+            id: "".to_string(),
+            url: None,
+            external_url: None,
+            title: None,
+            content: Content::Text("".into()),
+            summary: None,
+            image: None,
+            banner_image: None,
+            date_published: None,
+            date_modified: None,
+            author: None,
+            tags: None,
+            attachments: None,
+        }
+    }
+}
+
+impl Serialize for Item {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where S: Serializer
+    {
+        let mut state = serializer.serialize_struct("Item", 14)?;
+        state.serialize_field("id", &self.id)?;
+        if self.url.is_some() {
+            state.serialize_field("url", &self.url)?;
+        }
+        if self.external_url.is_some() {
+            state.serialize_field("external_url", &self.external_url)?;
+        }
+        if self.title.is_some() {
+            state.serialize_field("title", &self.title)?;
+        }
+        match self.content {
+            Content::Html(ref s) => {
+                state.serialize_field("content_html", s)?;
+                state.serialize_field("content_text", &None::<Option<&str>>)?;
+            },
+            Content::Text(ref s) => {
+                state.serialize_field("content_html", &None::<Option<&str>>)?;
+                state.serialize_field("content_text", s)?;
+            },
+            Content::Both(ref s, ref t) => {
+                state.serialize_field("content_html", s)?;
+                state.serialize_field("content_text", t)?;
+            },
+        };
+        if self.summary.is_some() {
+            state.serialize_field("summary", &self.summary)?;
+        }
+        if self.image.is_some() {
+            state.serialize_field("image", &self.image)?;
+        }
+        if self.banner_image.is_some() {
+            state.serialize_field("banner_image", &self.banner_image)?;
+        }
+        if self.date_published.is_some() {
+            state.serialize_field("date_published", &self.date_published)?;
+        }
+        if self.date_modified.is_some() {
+            state.serialize_field("date_modified", &self.date_modified)?;
+        }
+        if self.author.is_some() {
+            state.serialize_field("author", &self.author)?;
+        }
+        if self.tags.is_some() {
+            state.serialize_field("tags", &self.tags)?;
+        }
+        if self.attachments.is_some() {
+            state.serialize_field("attachments", &self.attachments)?;
+        }
+        state.end()
+    }
+}
+
+impl<'de> Deserialize<'de> for Item {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> 
+        where D: Deserializer<'de>
+    {
+        enum Field {
+            Id,
+            Url,
+            ExternalUrl,
+            Title,
+            ContentHtml,
+            ContentText,
+            Summary,
+            Image,
+            BannerImage,
+            DatePublished,
+            DateModified,
+            Author,
+            Tags,
+            Attachments,
+        };
+
+        impl<'de> Deserialize<'de> for Field {
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+                where D: Deserializer<'de>
+            {
+                struct FieldVisitor;
+
+                impl<'de> Visitor<'de> for FieldVisitor {
+                    type Value = Field;
+
+                    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                        formatter.write_str("non-expected field")
+                    }
+
+                    fn visit_str<E>(self, value: &str) -> Result<Field, E>
+                        where E: de::Error
+                    {
+                        match value {
+                            "id" => Ok(Field::Id),
+                            "url" => Ok(Field::Url),
+                            "external_url" => Ok(Field::ExternalUrl),
+                            "title" => Ok(Field::Title),
+                            "content_html" => Ok(Field::ContentHtml),
+                            "content_text" => Ok(Field::ContentText),
+                            "summary" => Ok(Field::Summary),
+                            "image" => Ok(Field::Image),
+                            "banner_image" => Ok(Field::BannerImage),
+                            "date_published" => Ok(Field::DatePublished),
+                            "date_modified" => Ok(Field::DateModified),
+                            "author" => Ok(Field::Author),
+                            "tags" => Ok(Field::Tags),
+                            "attachments" => Ok(Field::Attachments),
+                            _ => Err(de::Error::unknown_field(value, FIELDS)),
+                        }
+                    }
+                }
+
+                deserializer.deserialize_identifier(FieldVisitor)
+            }
+        }
+
+        struct ItemVisitor;
+
+        impl<'de> Visitor<'de> for ItemVisitor {
+            type Value = Item;
+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter.write_str("non-expected thing")
+            }
+
+            fn visit_map<V>(self, mut map: V) -> Result<Item, V::Error>
+                where V: MapAccess<'de>
+            {
+                let mut id = None;
+                let mut url = None;
+                let mut external_url = None;
+                let mut title = None;
+                let mut content_html: Option<String> = None;
+                let mut content_text: Option<String> = None;
+                let mut summary = None;
+                let mut image = None;
+                let mut banner_image = None;
+                let mut date_published = None;
+                let mut date_modified = None;
+                let mut author = None;
+                let mut tags = None;
+                let mut attachments = None;
+
+                while let Some(key) = map.next_key()? {
+                    match key {
+                        Field::Id => {
+                            if id.is_some() {
+                                return Err(de::Error::duplicate_field("id"));
+                            }
+                            id = Some(map.next_value()?);
+                        },
+                        Field::Url => {
+                            if url.is_some() {
+                                return Err(de::Error::duplicate_field("url"));
+                            }
+                            url = map.next_value()?;
+                        },
+                        Field::ExternalUrl => {
+                            if external_url.is_some() {
+                                return Err(de::Error::duplicate_field("external_url"));
+                            }
+                            external_url = map.next_value()?;
+                        },
+                        Field::Title => {
+                            if title.is_some() {
+                                return Err(de::Error::duplicate_field("title"));
+                            }
+                            title = map.next_value()?;
+                        },
+                        Field::ContentHtml => {
+                            if content_html.is_some() {
+                                return Err(de::Error::duplicate_field("content_html"));
+                            }
+                            content_html = map.next_value()?;
+                        },
+                        Field::ContentText => {
+                            if content_text.is_some() {
+                                return Err(de::Error::duplicate_field("content_text"));
+                            }
+                            content_text = map.next_value()?;
+                        },
+                        Field::Summary => {
+                            if summary.is_some() {
+                                return Err(de::Error::duplicate_field("summary"));
+                            }
+                            summary = map.next_value()?;
+                        },
+                        Field::Image => {
+                            if image.is_some() {
+                                return Err(de::Error::duplicate_field("image"));
+                            }
+                            image = map.next_value()?;
+                        },
+                        Field::BannerImage => {
+                            if banner_image.is_some() {
+                                return Err(de::Error::duplicate_field("banner_image"));
+                            }
+                            banner_image = map.next_value()?;
+                        },
+                        Field::DatePublished => {
+                            if date_published.is_some() {
+                                return Err(de::Error::duplicate_field("date_published"));
+                            }
+                            date_published = map.next_value()?;
+                        },
+                        Field::DateModified => {
+                            if date_modified.is_some() {
+                                return Err(de::Error::duplicate_field("date_modified"));
+                            }
+                            date_modified = map.next_value()?;
+                        },
+                        Field::Author => {
+                            if author.is_some() {
+                                return Err(de::Error::duplicate_field("author"));
+                            }
+                            author = map.next_value()?;
+                        },
+                        Field::Tags => {
+                            if tags.is_some() {
+                                return Err(de::Error::duplicate_field("tags"));
+                            }
+                            tags = map.next_value()?;
+                        },
+                        Field::Attachments => {
+                            if attachments.is_some() {
+                                return Err(de::Error::duplicate_field("attachments"));
+                            }
+                            attachments = map.next_value()?;
+                        },
+                    }
+                }
+
+                let id = id.ok_or_else(|| de::Error::missing_field("id"))?;
+                let content = match (content_html, content_text) {
+                    (Some(s), Some(t)) => {
+                        Content::Both(s.to_string(), t.to_string())
+                    },
+                    (Some(s), _) => {
+                        Content::Html(s.to_string())
+                    },
+                    (_, Some(t)) => {
+                        Content::Text(t.to_string())
+                    },
+                    _ => return Err(de::Error::missing_field("content_html or content_text")),
+                };
+
+                Ok(Item {
+                    id,
+                    url,
+                    external_url,
+                    title,
+                    content,
+                    summary,
+                    image,
+                    banner_image,
+                    date_published,
+                    date_modified,
+                    author,
+                    tags,
+                    attachments,
+                })
+            }
+        }
+
+        const FIELDS: &'static [&'static str] = &[
+            "id",
+            "url",
+            "external_url",
+            "title",
+            "content",
+            "summary",
+            "image",
+            "banner_image",
+            "date_published",
+            "date_modified",
+            "author",
+            "tags",
+            "attachments",
+        ];
+        deserializer.deserialize_struct("Item", FIELDS, ItemVisitor)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use feed::Author;
+    use serde_json;
+
+    #[test]
+    #[allow(non_snake_case)]
+    fn serialize_item__content_html() {
+        let item = Item {
+            id: "1".into(),
+            url: Some("http://example.com/feed.json".into()),
+            external_url: Some("http://example.com/feed.json".into()),
+            title: Some("feed title".into()),
+            content: Content::Html("<p>content</p>".into()),
+            summary: Some("feed summary".into()),
+            image: Some("http://img.com/blah".into()),
+            banner_image: Some("http://img.com/blah".into()),
+            date_published: Some("2017-01-01 10:00:00".into()),
+            date_modified: Some("2017-01-01 10:00:00".into()),
+            author: Some(Author::new().name("bob jones").url("http://example.com").avatar("http://img.com/blah")),
+            tags: Some(vec!["json".into(), "feed".into()]),
+            attachments: Some(vec![]),
+        };
+        assert_eq!(
+            serde_json::to_string(&item).unwrap(),
+            r#"{"id":"1","url":"http://example.com/feed.json","external_url":"http://example.com/feed.json","title":"feed title","content_html":"<p>content</p>","content_text":null,"summary":"feed summary","image":"http://img.com/blah","banner_image":"http://img.com/blah","date_published":"2017-01-01 10:00:00","date_modified":"2017-01-01 10:00:00","author":{"name":"bob jones","url":"http://example.com","avatar":"http://img.com/blah"},"tags":["json","feed"],"attachments":[]}"#
+        );
+    }
+
+    #[test]
+    #[allow(non_snake_case)]
+    fn serialize_item__content_text() {
+        let item = Item {
+            id: "1".into(),
+            url: Some("http://example.com/feed.json".into()),
+            external_url: Some("http://example.com/feed.json".into()),
+            title: Some("feed title".into()),
+            content: Content::Text("content".into()),
+            summary: Some("feed summary".into()),
+            image: Some("http://img.com/blah".into()),
+            banner_image: Some("http://img.com/blah".into()),
+            date_published: Some("2017-01-01 10:00:00".into()),
+            date_modified: Some("2017-01-01 10:00:00".into()),
+            author: Some(Author::new().name("bob jones").url("http://example.com").avatar("http://img.com/blah")),
+            tags: Some(vec!["json".into(), "feed".into()]),
+            attachments: Some(vec![]),
+        };
+        assert_eq!(
+            serde_json::to_string(&item).unwrap(),
+            r#"{"id":"1","url":"http://example.com/feed.json","external_url":"http://example.com/feed.json","title":"feed title","content_html":null,"content_text":"content","summary":"feed summary","image":"http://img.com/blah","banner_image":"http://img.com/blah","date_published":"2017-01-01 10:00:00","date_modified":"2017-01-01 10:00:00","author":{"name":"bob jones","url":"http://example.com","avatar":"http://img.com/blah"},"tags":["json","feed"],"attachments":[]}"#
+        );
+    }
+
+    #[test]
+    #[allow(non_snake_case)]
+    fn serialize_item__content_both() {
+        let item = Item {
+            id: "1".into(),