From 69a52b6c7e057644df8dd60d1ff7a8aaee6abaa6 Mon Sep 17 00:00:00 2001
From: Chris Tsang <tyt2y7@gmail.com>
Date: Fri, 7 May 2021 21:37:29 +0800
Subject: [PATCH] Use generic for try_get

---
 src/query/result.rs   | 51 ++++++++++++++++++++++++++++---------------
 src/tests_cfg/cake.rs |  4 ++--
 2 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/src/query/result.rs b/src/query/result.rs
index 3225612f..39fc8b30 100644
--- a/src/query/result.rs
+++ b/src/query/result.rs
@@ -14,38 +14,47 @@ pub(crate) enum QueryResultRow {
 #[derive(Debug)]
 pub struct TypeErr;
 
-// QueryResult //
+pub trait TryGetable {
+    fn try_get(res: &QueryResult, col: &str) -> Result<Self, TypeErr>
+    where
+        Self: std::marker::Sized;
+}
 
-impl QueryResult {
-    pub fn try_get_i32(&self, col: &str) -> Result<i32, TypeErr> {
-        match &self.row {
+// TryGetable //
+
+impl TryGetable for i32 {
+    fn try_get(res: &QueryResult, col: &str) -> Result<Self, TypeErr> {
+        match &res.row {
             QueryResultRow::SqlxMySql(row) => {
                 use sqlx::Row;
-
-                if let Ok(val) = row.try_get(col) {
-                    Ok(val)
-                } else {
-                    Err(TypeErr)
-                }
+                Ok(row.try_get(col)?)
             }
         }
     }
+}
 
-    pub fn try_get_string(&self, col: &str) -> Result<String, TypeErr> {
-        match &self.row {
+impl TryGetable for String {
+    fn try_get(res: &QueryResult, col: &str) -> Result<Self, TypeErr> {
+        match &res.row {
             QueryResultRow::SqlxMySql(row) => {
                 use sqlx::Row;
-
-                if let Ok(val) = row.try_get(col) {
-                    Ok(val)
-                } else {
-                    Err(TypeErr)
-                }
+                Ok(row.try_get(col)?)
             }
         }
     }
 }
 
+// QueryResult //
+
+impl QueryResult {
+    pub fn try_get<T>(&self, col: &str) -> Result<T, TypeErr>
+    where
+        T: TryGetable,
+    {
+        T::try_get(self, col)
+    }
+}
+
 // TypeErr //
 
 impl Error for TypeErr {}
@@ -55,3 +64,9 @@ impl fmt::Display for TypeErr {
         write!(f, "{:?}", self)
     }
 }
+
+impl From<sqlx::Error> for TypeErr {
+    fn from(_: sqlx::Error) -> TypeErr {
+        TypeErr
+    }
+}
diff --git a/src/tests_cfg/cake.rs b/src/tests_cfg/cake.rs
index f8243e85..9b12a39b 100644
--- a/src/tests_cfg/cake.rs
+++ b/src/tests_cfg/cake.rs
@@ -53,8 +53,8 @@ impl Relation for CakeRelation {
 impl Model for CakeModel {
     fn from_query_result(row: QueryResult) -> Result<Self, TypeErr> {
         Ok(Self {
-            id: row.try_get_i32("id")?,
-            name: row.try_get_string("name")?,
+            id: row.try_get("id")?,
+            name: row.try_get("name")?,
         })
     }
 }