Support for nested structs in sql layer

src/api/lib.zig

@@ -85,7 +85,7 @@ pub const TimelineArgs = struct {
 };
 
 pub const TimelineResult = struct {
-    items: []services.notes.Note,
+    items: []services.notes.NoteDetailed,
 
     prev_page: TimelineArgs,
     next_page: TimelineArgs,

src/api/services/actors.zig

@@ -13,6 +13,13 @@ pub const CreateError = error{
     DatabaseFailure,
 };
 
+pub const ActorDetailed = struct {
+    id: Uuid,
+    username: []const u8,
+    host: []const u8,
+    created_at: DateTime,
+};
+
 pub const LookupError = error{
     DatabaseFailure,
 };

src/api/services/notes.zig

@@ -14,6 +14,17 @@ pub const Note = struct {
     created_at: DateTime,
 };
 
+pub const NoteDetailed = struct {
+    id: Uuid,
+
+    author: struct {
+        id: Uuid,
+        username: []const u8,
+    },
+    content: []const u8,
+    created_at: DateTime,
+};
+
 pub const CreateError = error{
     DatabaseFailure,
 };
@@ -81,7 +92,7 @@ pub const QueryArgs = struct {
 };
 
 pub const QueryResult = struct {
-    items: []Note,
+    items: []NoteDetailed,
 
     prev_page: QueryArgs,
     next_page: QueryArgs,
@@ -91,7 +102,9 @@ pub fn query(db: anytype, args: QueryArgs, alloc: std.mem.Allocator) !QueryResul
     var builder = sql.QueryBuilder.init(alloc);
     defer builder.deinit();
 
-    try builder.appendSlice(selectStarFromNote ++
+    try builder.appendSlice(
+        \\SELECT note.id, note.content, note.created_at, actor.id AS "author.id", actor.username AS "author.username"
+        \\FROM note
         \\  JOIN actor ON actor.id = note.author_id
         \\
     );
@@ -140,7 +153,7 @@ pub fn query(db: anytype, args: QueryArgs, alloc: std.mem.Allocator) !QueryResul
     };
 
     const results = try db.queryRowsWithOptions(
-        Note,
+        NoteDetailed,
         try builder.terminate(),
         query_args,
         max_items,

src/sql/lib.zig

@@ -120,12 +120,60 @@ const RawResults = union(Engine) {
     }
 };
 
+fn FieldPtr(comptime Ptr: type, comptime names: []const []const u8) type {
+    if (names.len == 0) return Ptr;
+
+    const T = std.meta.Child(Ptr);
+
+    const field = for (@typeInfo(T).Struct.fields) |f| {
+        if (std.mem.eql(u8, f.name, names[0])) break f;
+    } else @compileError("Unknown field " ++ names[0] ++ " in type " ++ @typeName(T));
+
+    return FieldPtr(*field.field_type, names[1..]);
+}
+
+fn fieldPtr(ptr: anytype, comptime names: []const []const u8) FieldPtr(@TypeOf(ptr), names) {
+    if (names.len == 0) return ptr;
+
+    return fieldPtr(&@field(ptr.*, names[0]), names[1..]);
+}
+
+fn isScalar(comptime T: type) bool {
+    if (comptime std.meta.trait.isZigString(T)) return true;
+    if (comptime std.meta.trait.isIntegral(T)) return true;
+    if (comptime std.meta.trait.isFloat(T)) return true;
+    if (comptime std.meta.trait.is(.Enum)(T)) return true;
+    if (T == bool) return true;
+    if (comptime std.meta.trait.hasFn("parse")(T)) return true;
+
+    if (comptime std.meta.trait.is(.Optional)(T) and isScalar(std.meta.Child(T))) return true;
+
+    return false;
+}
+
+fn recursiveFieldPaths(comptime T: type, comptime prefix: []const []const u8) []const []const []const u8 {
+    comptime {
+        var fields: []const []const []const u8 = &.{};
+
+        for (std.meta.fields(T)) |f| {
+            const full_name = prefix ++ [_][]const u8{f.name};
+            if (isScalar(f.field_type)) {
+                fields = fields ++ [_][]const []const u8{full_name};
+            } else {
+                fields = fields ++ recursiveFieldPaths(f.field_type, full_name);
+            }
+        }
+
+        return fields;
+    }
+}
+
 // Represents a set of results.
 // row() must be called until it returns null, or the query may not complete
 // Must be deallocated by a call to finish()
 pub fn Results(comptime T: type) type {
     // would normally make this a declaration of the struct, but it causes the compiler to crash
-    const fields = if (T == void) .{} else std.meta.fields(T);
+    const fields = if (T == void) .{} else recursiveFieldPaths(T, &.{});
     return struct {
         const Self = @This();
 
@@ -141,13 +189,16 @@ pub fn Results(comptime T: type) type {
             return Self{ .underlying = underlying, .column_indices = blk: {
                 var indices: [fields.len]u15 = undefined;
                 inline for (fields) |f, i| {
-                    indices[i] = if (!std.meta.trait.isTuple(T))
-                        underlying.columnIndex(f.name) catch {
-                            std.log.err("Could not find column index for field {s}", .{f.name});
+                    if (comptime std.meta.trait.isTuple(T)) {
+                        indices[i] = i;
+                    } else {
+                        const name = util.comptimeJoin(".", f);
+                        indices[i] =
+                            underlying.columnIndex(name) catch {
+                            std.log.err("Could not find column index for field {s}", .{name});
                             return error.ColumnMismatch;
+                        };
                     }
-                    else
-                        i;
                 }
                 break :blk indices;
             } };
@@ -168,15 +219,19 @@ pub fn Results(comptime T: type) type {
                     // Iteration bounds must be defined at comptime (inline for) but the number of fields we could
                     // successfully allocate is defined at runtime. So we iterate over the entire field array and
                     // conditionally deallocate fields in the loop.
-                    if (i < fields_allocated) util.deepFree(alloc, @field(result, f.name));
+                    const ptr = fieldPtr(&result, f);
+                    if (i < fields_allocated) util.deepFree(alloc, ptr.*);
                 };
 
                 inline for (fields) |f, i| {
                     // TODO: Causes compiler segfault. why?
                     //const F = f.field_type;
-                    const F = @TypeOf(@field(result, f.name));
-                    @field(result, f.name) = row_val.get(F, self.column_indices[i], alloc) catch |err| {
-                        std.log.err("SQL: Error getting column {s} of type {}", .{ f.name, F });
+                    //const F = @TypeOf(@field(result, f.name));
+                    const F = std.meta.Child(FieldPtr(*@TypeOf(result), f));
+                    const ptr = fieldPtr(&result, f);
+                    const name = util.comptimeJoin(".", f);
+                    ptr.* = row_val.get(F, self.column_indices[i], alloc) catch |err| {
+                        std.log.err("SQL: Error getting column {s} of type {}", .{ name, F });
                         return err;
                     };
                     fields_allocated += 1;