Merge pull request #104 from xsnippet/crud-storage

The initial implementation of the storage layer

.github/workflows/tests.yml

@@ -72,7 +72,7 @@ jobs:
           sudo -u postgres createuser -s devel
           sudo -u postgres createdb -O devel devel
           sudo -u postgres psql -c "ALTER USER devel PASSWORD 'devel';" devel
-          echo '::set-env name=DATABASE_URL::postgres://devel:devel@localhost/devel'
+          echo '::set-env name=ROCKET_DATABASE_URL::postgres://devel:devel@localhost/devel'
 
       - name: Start PostgreSQL and create a database (MacOS)
         if: runner.os == 'macOS'
@@ -81,7 +81,7 @@ jobs:
           /usr/local/opt/postgres/bin/createuser -s devel
           /usr/local/opt/postgres/bin/createdb -O devel devel
           /usr/local/opt/postgres/bin/psql -c "ALTER USER devel PASSWORD 'devel';" devel
-          echo '::set-env name=DATABASE_URL::postgres://devel:devel@localhost/devel'
+          echo '::set-env name=ROCKET_DATABASE_URL::postgres://devel:devel@localhost/devel'
 
       - name: Start PostgreSQL and create a database (Windows)
         if: runner.os == 'Windows'
@@ -95,7 +95,7 @@ jobs:
           "C:\Program Files\PostgreSQL\12\bin\createuser" -s devel
           "C:\Program Files\PostgreSQL\12\bin\createdb" -O devel devel
           "C:\Program Files\PostgreSQL\12\bin\psql" -c "ALTER USER devel PASSWORD 'devel';" devel
-          echo '::set-env name=DATABASE_URL::postgres://devel:devel@localhost/devel'
+          echo '::set-env name=ROCKET_DATABASE_URL::postgres://devel:devel@localhost/devel'
 
       - name: Install Alembic and psycopg2
         run: |

Cargo.toml

@@ -17,6 +17,7 @@ publish = false
 
 [dependencies]
 chrono = "0.4.13"
-diesel = { version = "1.4.5", features = ["postgres"] }
+diesel = { version = "1.4.5", features = ["chrono", "postgres", "r2d2"] }
+rand = "0.7.3"
 rocket = "0.4.5"
 rocket_contrib = {version = "0.4.5", features = ["json"]}

src/application.rs

@@ -2,6 +2,7 @@ use std::collections::HashSet;
 use std::error::Error;
 
 use super::routes;
+use super::storage::{SqlStorage, Storage};
 
 #[derive(Debug)]
 pub struct Config {
@@ -34,7 +35,14 @@ pub fn create_app() -> Result<rocket::Rocket, Box<dyn Error>> {
         Err(err) => return Err(Box::new(err)),
     };
 
+    let database_url = match app.config().get_string("database_url") {
+        Ok(database_url) => database_url,
+        Err(err) => return Err(Box::new(err)),
+    };
+    let storage: Box<dyn Storage> = Box::new(SqlStorage::new(&database_url)?);
+
     Ok(app
         .manage(Config { syntaxes })
+        .manage(storage)
         .mount("/v1", routes![routes::syntaxes::get_syntaxes]))
 }

src/storage/errors.rs

@@ -0,0 +1,63 @@
+use std::error;
+use std::fmt;
+
+/// All errors that can be returned by the storage layer wrapped into a single
+/// enum type for convinience.
+#[derive(Debug)]
+pub enum StorageError {
+    /// Snippet with this id already exists in the database
+    Duplicate { id: String },
+    /// Snippet with this id can't be found
+    NotFound { id: String },
+    /// All other errors that can't be handled by the storage layer
+    InternalError(Box<dyn error::Error>),
+}
+
+impl fmt::Display for StorageError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            StorageError::Duplicate { id } => write!(f, "Snippet with id `{}` already exists", id),
+            StorageError::NotFound { id } => write!(f, "Snippet with id `{}` is not found", id),
+            StorageError::InternalError(e) => write!(f, "Internal error: `{}`", e),
+        }
+    }
+}
+
+// this is not strictly required, but allows for wrapping a StorageError
+// instance into a Box<dyn Error> if needed. Error's only requirement is for
+// a type to implement Debug + Display
+impl error::Error for StorageError {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_display() {
+        assert_eq!(
+            "Snippet with id `spam` already exists",
+            format!(
+                "{}",
+                StorageError::Duplicate {
+                    id: "spam".to_string()
+                }
+            )
+        );
+
+        assert_eq!(
+            "Snippet with id `eggs` is not found",
+            format!(
+                "{}",
+                StorageError::NotFound {
+                    id: "eggs".to_string()
+                }
+            )
+        );
+
+        let error = "foo".parse::<f32>().err().unwrap();
+        assert_eq!(
+            "Internal error: `invalid float literal`",
+            format!("{}", StorageError::InternalError(Box::new(error)))
+        );
+    }
+}

src/storage/mod.rs

@@ -1 +1,27 @@
-pub mod sql;
+mod errors;
+mod models;
+mod sql;
+
+pub use errors::StorageError;
+pub use models::{Changeset, Snippet};
+pub use sql::SqlStorage;
+
+/// CRUD interface for storing/loading snippets from a persistent storage.
+///
+/// Types implementing this trait are required to be both Send and Sync, so
+/// that their instances can be safely shared between multiple threads.
+pub trait Storage: Send + Sync {
+    /// Save the state of the given snippet to the persistent storage.
+    fn create(&self, snippet: &Snippet) -> Result<Snippet, StorageError>;
+
+    /// Returns the snippet uniquely identified by a given id (a slug or a
+    /// legacy numeric id)
+    fn get(&self, id: &str) -> Result<Snippet, StorageError>;
+
+    /// Update the state of the given snippet in the persistent storage
+    fn update(&self, snippet: &Snippet) -> Result<Snippet, StorageError>;
+
+    /// Delete the snippet uniquely identified by a given id (a slug or a legacy
+    /// numeric id)
+    fn delete(&self, id: &str) -> Result<(), StorageError>;
+}