Add query builder struct
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1 changed files with 99 additions and 3 deletions
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@ -16,7 +16,7 @@ fn baseTypeName(comptime T: type) []const u8 {
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}
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}
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fn tableName(comptime T: type) String {
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fn tableName(comptime T: type) String {
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return util.case.pascalToSnake(baseTypeName(T));
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return comptime util.case.pascalToSnake(baseTypeName(T));
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}
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}
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// Represents a table bound to an identifier in a sql query
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// Represents a table bound to an identifier in a sql query
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@ -29,6 +29,20 @@ pub const QueryTable = struct {
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const f = @as(std.meta.FieldEnum(self.Model), lit);
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const f = @as(std.meta.FieldEnum(self.Model), lit);
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return comptimePrint("{s}.{s}", .{ self.as, @tagName(f) });
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return comptimePrint("{s}.{s}", .{ self.as, @tagName(f) });
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}
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}
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pub fn select(comptime self: QueryTable, comptime lit: @Type(.EnumLiteral)) ResultColumn {
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return .{
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.@"type" = std.meta.fieldInfo(self.Model, lit).field_type,
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.field = self.field(lit),
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};
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}
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// returns the declaration to put in the FROM clause
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fn declarationStr(comptime self: QueryTable) String {
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comptime {
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return comptimePrint("{s} AS {s}", .{ tableName(self.Model), self.as });
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}
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}
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};
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};
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fn makeQueryTable(comptime Model: type, comptime table_index: usize) QueryTable {
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fn makeQueryTable(comptime Model: type, comptime table_index: usize) QueryTable {
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@ -51,6 +65,16 @@ test "QueryTable.field" {
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try std.testing.expectEqualStrings("my_type.id", tbl.field(.id));
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try std.testing.expectEqualStrings("my_type.id", tbl.field(.id));
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}
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}
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test "QueryTable.declarationStr" {
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const MyTable = struct { id: i64 };
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const tbl = QueryTable{
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.Model = MyTable,
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.as = "some_table",
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};
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try std.testing.expectEqualStrings("my_table AS some_table", tbl.declarationStr());
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}
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test "queryTables constructor" {
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test "queryTables constructor" {
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const MyTable = struct { id: i64 };
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const MyTable = struct { id: i64 };
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const MyOtherTable = struct { val: i64 };
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const MyOtherTable = struct { val: i64 };
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@ -63,9 +87,14 @@ test "queryTables constructor" {
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try std.testing.expectEqualStrings("my_other_table_1", qt[1].as);
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try std.testing.expectEqualStrings("my_other_table_1", qt[1].as);
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}
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}
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fn map(comptime T: type, comptime R: type, comptime vals: []const T, comptime func: fn (T, usize) R) *const [vals.len]R {
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fn map(comptime T: type, comptime R: type, comptime vals: []const T, comptime func: anytype) *const [vals.len]R {
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var result: [vals.len]R = undefined;
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var result: [vals.len]R = undefined;
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for (vals) |v, i| result[i] = func(v, i);
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if (@typeInfo(@TypeOf(func)).Fn.args.len == 2) {
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for (vals) |v, i| result[i] = @as(R, func(v, i));
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} else {
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for (vals) |v, i| result[i] = @as(R, func(v));
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}
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return &result;
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return &result;
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}
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}
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@ -134,3 +163,70 @@ test "Condition.str()" {
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} }).str(),
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} }).str(),
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);
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);
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}
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}
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const ResultColumn = struct {
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@"type": type,
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field: []const u8,
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pub fn toSelectClause(comptime self: ResultColumn) String {
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return self.field;
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}
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pub fn toStructField(comptime self: ResultColumn) std.builtin.Type.StructField {
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return .{
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.name = self.field,
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.field_type = self.@"type",
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.default_value = null,
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.is_comptime = false,
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.alignment = 0,
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};
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}
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};
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// Represents a full SQL query
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pub const Query = struct {
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tables: []const QueryTable,
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fields: []const ResultColumn,
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filter: Condition,
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pub fn str(comptime self: Query) String {
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const table_aliases = map(QueryTable, String, self.tables, QueryTable.declarationStr);
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const select_clauses = map(ResultColumn, String, self.fields, ResultColumn.toSelectClause);
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return comptimePrint("SELECT {s} FROM {s} WHERE {s}", .{ join(select_clauses, ", "), join(table_aliases, ", "), self.filter.str() });
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}
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pub fn rowType(comptime self: Query) type {
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const struct_fields = map(ResultColumn, std.builtin.Type.StructField, self.fields, ResultColumn.toStructField);
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return @Type(.{ .Struct = .{
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.layout = .Auto,
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.fields = struct_fields,
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.decls = &.{},
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.is_tuple = true,
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} });
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}
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};
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test "Query" {
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const MyTable = struct { id: i64 };
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const MyOtherTable = struct {
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val: []const u8,
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};
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const qt = queryTables(&.{ MyTable, MyOtherTable, MyTable });
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const q = comptime Query{
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.tables = qt,
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.fields = &.{ qt[0].select(.id), qt[1].select(.val) },
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.filter = Condition{ .eql = .{ .lhs = qt[0].field(.id), .rhs = qt[2].field(.id) } },
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};
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try std.testing.expectEqualStrings(
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"SELECT my_table_0.id, my_other_table_1.val " ++
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"FROM my_table AS my_table_0, my_other_table AS my_other_table_1, my_table AS my_table_2 " ++
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"WHERE (my_table_0.id = my_table_2.id)",
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comptime q.str(),
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);
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const fields = std.meta.fields(q.rowType());
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try std.testing.expectEqual(i64, fields[0].field_type);
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try std.testing.expectEqual([]const u8, fields[1].field_type);
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}
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