Rework ToSql to be implementable without unsafe.

src/types/mod.rs

@@ -50,10 +50,8 @@
 //! `FromSql` for the cases where you want to know if a value was NULL (which gets translated to
 //! `None`).
 
-pub use ffi::sqlite3_stmt;
-
 pub use self::from_sql::FromSql;
-pub use self::to_sql::ToSql;
+pub use self::to_sql::{ToSql, ToSqlOutput};
 pub use self::value_ref::ValueRef;
 
 mod value_ref;
@@ -102,6 +100,42 @@ pub enum Value {
     Blob(Vec<u8>),
 }
 
+impl From<Null> for Value {
+    fn from(_: Null) -> Value {
+        Value::Null
+    }
+}
+
+impl From<i32> for Value {
+    fn from(i: i32) -> Value {
+        Value::Integer(i as i64)
+    }
+}
+
+impl From<i64> for Value {
+    fn from(i: i64) -> Value {
+        Value::Integer(i)
+    }
+}
+
+impl From<f64> for Value {
+    fn from(f: f64) -> Value {
+        Value::Real(f)
+    }
+}
+
+impl From<String> for Value {
+    fn from(s: String) -> Value {
+        Value::Text(s)
+    }
+}
+
+impl From<Vec<u8>> for Value {
+    fn from(v: Vec<u8>) -> Value {
+        Value::Blob(v)
+    }
+}
+
 #[cfg(test)]
 #[cfg_attr(feature="clippy", allow(similar_names))]
 mod test {
@@ -111,6 +145,7 @@ mod test {
     use Error;
     use libc::{c_int, c_double};
     use std::f64::EPSILON;
+    use super::Value;
 
     fn checked_memory_handle() -> Connection {
         let db = Connection::open_in_memory().unwrap();
@@ -133,6 +168,17 @@ mod test {
     fn test_str() {
         let db = checked_memory_handle();
 
+        let s = "hello, world!";
+        db.execute("INSERT INTO foo(t) VALUES (?)", &[&s]).unwrap();
+
+        let from: String = db.query_row("SELECT t FROM foo", &[], |r| r.get(0)).unwrap();
+        assert_eq!(from, s);
+    }
+
+    #[test]
+    fn test_string() {
+        let db = checked_memory_handle();
+
         let s = "hello, world!";
         db.execute("INSERT INTO foo(t) VALUES (?)", &[&s.to_owned()]).unwrap();
 
@@ -140,6 +186,15 @@ mod test {
         assert_eq!(from, s);
     }
 
+    #[test]
+    fn test_value() {
+        let db = checked_memory_handle();
+
+        db.execute("INSERT INTO foo(i) VALUES (?)", &[&Value::Integer(10)]).unwrap();
+
+        assert_eq!(10i64, db.query_row("SELECT i FROM foo", &[], |r| r.get(0)).unwrap());
+    }
+
     #[test]
     fn test_option() {
         let db = checked_memory_handle();