Expose fallibility of individual SQL results

`LocalGeneration::sql::files()` runs an SQL query, iterates over the
results and collects the rows into a `Vec`. This can fail at any step:
the query might fail to run, or one of the rows might fail to be fetched
or processed.

Right now, we lump all those failures into a `Result` that wraps the
whole return value. This is only possible because we process each row
before returning. Once `Vec` is replaced by an iterator, we won't have
that luxury anymore, so we now wrap each individual element into its own
`Result` (as well as wrapping the whole vector into a `Result` of its
own).

1 files changed, 14 insertions, 6 deletions

diff --git a/src/generation.rs b/src/generation.rs
index 1d0ee52..a780203 100644
--- a/src/generation.rs
+++ b/src/generation.rs
@@ -196,7 +196,7 @@ impl LocalGeneration {
         sql::file_count(&self.conn)
     }
 
-    pub fn files(&self) -> LocalGenerationResult<Vec<BackedUpFile>> {
+    pub fn files(&self) -> LocalGenerationResult<Vec<LocalGenerationResult<BackedUpFile>>> {
         sql::files(&self.conn)
     }
 
@@ -289,14 +289,22 @@ mod sql {
         Ok(count)
     }
 
-    pub fn files(conn: &Connection) -> LocalGenerationResult<Vec<BackedUpFile>> {
+    pub fn files(
+        conn: &Connection,
+    ) -> LocalGenerationResult<Vec<LocalGenerationResult<BackedUpFile>>> {
         let mut stmt = conn.prepare("SELECT * FROM files")?;
         let iter = stmt.query_map(params![], |row| row_to_entry(row))?;
-        let mut files = vec![];
+        let mut files: Vec<LocalGenerationResult<BackedUpFile>> = vec![];
         for x in iter {
-            let (fileno, json, reason) = x?;
-            let entry = serde_json::from_str(&json)?;
-            files.push(BackedUpFile::new(fileno, entry, &reason));
+            match x {
+                Ok((fileno, json, reason)) => {
+                    let result = serde_json::from_str(&json)
+                        .map(|entry| BackedUpFile::new(fileno, entry, &reason))
+                        .map_err(|e| e.into());
+                    files.push(result)
+                }
+                Err(e) => files.push(Err(e.into())),
+            }
         }
         Ok(files)
     }