Infer schema properly when array columns are used

Note: We don't ever actually use the added column, because we don't need
to. Its presence alone is enough to cause the tests to fail.

This implementation is a hack. It's awful. I need to write a more
extensible system for type lookups. But right now I don't care. This is
blocking 0.4, and I can fix it in 0.5.

Fixes #65

CHANGELOG.md

@@ -27,6 +27,9 @@ for Rust libraries in [RFC #1105](https://github.com/rust-lang/rfcs/blob/master/
 * `#[changeset_for]` can now be used with structs containing only a single field
   other than `id`. Fixes [#66](https://github.com/sgrif/diesel/issues/66).
 
+* `infer_schema!` properly works with array columns. Fixes
+  [#65](https://github.com/sgrif/diesel/issues/65).
+
 ## [0.3.0] 2015-12-04
 
 ### Changed

diesel_codegen/src/schema_inference/mod.rs

@@ -144,11 +144,24 @@ fn table_oid(conn: &Connection, table_name: &str) -> QueryResult<u32> {
 
 fn column_def_tokens(cx: &mut ExtCtxt, attr: &PgAttr) -> Vec<ast::TokenTree> {
     let column_name = str_to_ident(&attr.column_name);
-    let type_name = str_to_ident(&capitalize(&attr.type_name));
+    let tpe = determine_column_type(cx, attr);
+    quote_tokens!(cx, $column_name -> $tpe,)
+}
+
+fn determine_column_type(cx: &mut ExtCtxt, attr: &PgAttr) -> P<ast::Ty> {
+    let tpe;
+    if attr.type_name.starts_with("_") {
+        let subtype = str_to_ident(&capitalize(&attr.type_name[1..]));
+        tpe = quote_ty!(cx, Array<$subtype>);
+    } else {
+        let type_name = str_to_ident(&capitalize(&attr.type_name));
+        tpe = quote_ty!(cx, $type_name);
+    }
+
     if attr.nullable {
-        quote_tokens!(cx, $column_name -> Nullable<$type_name>,)
+        quote_ty!(cx, Nullable<$tpe>)
     } else {
-        quote_tokens!(cx, $column_name -> $type_name,)
+        tpe
     }
 }
 

diesel_tests/migrations/20160107090901_add_tags_to_posts/down.sql

@@ -0,0 +1 @@
+ALTER TABLE posts DROP COLUMN tags;

diesel_tests/migrations/20160107090901_add_tags_to_posts/up.sql

@@ -0,0 +1 @@
+ALTER TABLE posts ADD COLUMN tags varchar[] NOT NULL DEFAULT '{}';

diesel_tests/tests/schema.rs

@@ -37,6 +37,7 @@ pub struct Post {
     pub user_id: i32,
     pub title: String,
     pub body: Option<String>,
+    pub tags: Vec<String>,
 }
 
 impl Post {
@@ -46,6 +47,7 @@ impl Post {
             user_id: user_id,
             title: title.to_string(),
             body: body.map(|s| s.to_string()),
+            tags: Vec::new(),
         }
     }
 }