Added get_items_by_url, to fetch multiple items at once

src/calendar/cached_calendar.rs

@@ -326,6 +326,14 @@ impl DavCalendar for CachedCalendar {
         Ok(self.items.get(url).cloned())
     }
 
+    async fn get_items_by_url(&self, urls: &[Url]) -> Result<Vec<Option<Item>>, Box<dyn Error>> {
+        let mut v = Vec::new();
+        for url in urls {
+            v.push(DavCalendar::get_item_by_url(self, url).await?);
+        }
+        Ok(v)
+    }
+
     async fn delete_item(&mut self, item_url: &Url) -> Result<(), Box<dyn Error>> {
         #[cfg(feature = "local_calendar_mocks_remote_calendars")]
         self.mock_behaviour.as_ref().map_or(Ok(()), |b| b.lock().unwrap().can_delete_item())?;

src/calendar/remote_calendar.rs

@@ -14,6 +14,7 @@ use crate::item::Item;
 use crate::item::VersionTag;
 use crate::item::SyncStatus;
 use crate::resource::Resource;
+use crate::utils::find_elem;
 
 static TASKS_BODY: &str = r#"
     <c:calendar-query xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav">
@@ -28,6 +29,15 @@ static TASKS_BODY: &str = r#"
     </c:calendar-query>
 "#;
 
+static MULTIGET_BODY_PREFIX: &str = r#"
+    <c:calendar-multiget xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav">
+        <d:prop>
+            <c:calendar-data />
+        </d:prop>
+"#;
+static MULTIGET_BODY_SUFFIX: &str = r#"
+    </c:calendar-multiget>
+"#;
 
 
 
@@ -191,6 +201,40 @@ impl DavCalendar for RemoteCalendar {
         Ok(Some(item))
     }
 
+    async fn get_items_by_url(&self, urls: &[Url]) -> Result<Vec<Option<Item>>, Box<dyn Error>> {
+        // Build the request body
+        let mut hrefs = String::new();
+        for url in urls {
+            hrefs.push_str(&format!("        <d:href>{}</d:href>\n", url.path()));
+        }
+        let body = format!("{}{}{}", MULTIGET_BODY_PREFIX, hrefs, MULTIGET_BODY_SUFFIX);
+
+        // Send the request
+        let xml_replies = crate::client::sub_request_and_extract_elems(&self.resource, "REPORT", body, "response").await?;
+
+        // This is supposed to be cached
+        let version_tags = self.get_item_version_tags().await?;
+
+        // Parse the results
+        let mut results = Vec::new();
+        for xml_reply in xml_replies {
+            let href = find_elem(&xml_reply, "href").ok_or("Missing HREF")?.text();
+            let mut url = self.resource.url().clone();
+            url.set_path(&href);
+            let ical_data = find_elem(&xml_reply, "calendar-data").ok_or("Missing calendar-data")?.text();
+
+            let vt = match version_tags.get(&url) {
+                None => return Err(format!("Inconsistent data: {} has no version tag", url).into()),
+                Some(vt) => vt,
+            };
+
+            let item = crate::ical::parse(&ical_data, url.clone(), SyncStatus::Synced(vt.clone()))?;
+            results.push(Some(item));
+        }
+
+        Ok(results)
+    }
+
     async fn delete_item(&mut self, item_url: &Url) -> Result<(), Box<dyn Error>> {
         let del_response = reqwest::Client::new()
             .delete(item_url.clone())

src/traits.rs

@@ -83,6 +83,10 @@ pub trait DavCalendar : BaseCalendar {
     /// Returns a particular item
     async fn get_item_by_url(&self, url: &Url) -> Result<Option<Item>, Box<dyn Error>>;
 
+    /// Returns a set of items.
+    /// This is usually faster than calling multiple consecutive [`get_item_by_url`], since it only issues one HTTP request.
+    async fn get_items_by_url(&self, urls: &[Url]) -> Result<Vec<Option<Item>>, Box<dyn Error>>;
+
     /// Delete an item
     async fn delete_item(&mut self, item_url: &Url) -> Result<(), Box<dyn Error>>;