From 22d087fcc09b932b41ec5eacece4f722ef41ee06 Mon Sep 17 00:00:00 2001
From: Vincent Rischmann
Date: Wed, 6 Jan 2021 02:02:24 +0100
Subject: allow binding and reading optionals

Also allow binding the '(null)' value.
---
 sqlite.zig | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

(limited to 'sqlite.zig')

diff --git a/sqlite.zig b/sqlite.zig
index d96c956..2600ee2 100644
--- a/sqlite.zig
+++ b/sqlite.zig
@@ -548,6 +548,29 @@ pub fn Iterator(comptime Type: type) type {
             return ret;
         }
 
+        fn readOptional(self: *Self, comptime OptionalType: type, options: anytype, _i: usize) !OptionalType {
+            const i = @intCast(c_int, _i);
+            const type_info = @typeInfo(OptionalType);
+
+            var ret: OptionalType = undefined;
+            switch (type_info) {
+                .Optional => |opt| {
+                    // Easy way to know if the column represents a null value.
+                    const value = c.sqlite3_column_value(self.stmt, i);
+                    const datatype = c.sqlite3_value_type(value);
+
+                    if (datatype == c.SQLITE_NULL) {
+                        return null;
+                    } else {
+                        const val = try self.readField(opt.child, _i, options);
+                        ret = val;
+                        return ret;
+                    }
+                },
+                else => @compileError("cannot read optional of type " ++ @typeName(OptionalType)),
+            }
+        }
+
         // readStruct reads an entire sqlite row into a struct.
         //
         // Each field correspond to a column; its position in the struct determines the column used for it.
@@ -596,6 +619,7 @@ pub fn Iterator(comptime Type: type) type {
                     .Void => {},
                     .Array => try self.readArray(FieldType, i),
                     .Pointer => try self.readPointer(FieldType, options.allocator, i),
+                    .Optional => try self.readOptional(FieldType, options, i),
                     else => @compileError("cannot populate field of type " ++ @typeName(FieldType)),
                 },
             };
@@ -758,6 +782,12 @@ pub fn Statement(comptime opts: StatementOptions, comptime query: ParsedQuery) t
                             else => @compileError("cannot bind field " ++ field_name ++ " of type array of " ++ @typeName(arr.child)),
                         }
                     },
+                    .Optional => |opt| if (field) |non_null_field| {
+                        self.bindField(opt.child, field_name, i, non_null_field);
+                    } else {
+                        _ = c.sqlite3_bind_null(self.stmt, column);
+                    },
+                    .Null => _ = c.sqlite3_bind_null(self.stmt, column),
                     else => @compileError("cannot bind field " ++ field_name ++ " of type " ++ @typeName(FieldType)),
                 },
             }
@@ -1403,8 +1433,8 @@ test "sqlite: optional" {
     );
 
     testing.expect(row != null);
-    testing.expect(row.data == null);
-    testing.expectEqual(true, row.is_published.?);
+    testing.expect(row.?.data == null);
+    testing.expectEqual(true, row.?.is_published.?);
 }
 
 test "sqlite: statement reset" {
-- 
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