Add basic, tailored SQL ORM mapper

netquery/orm/query_runner.go

@@ -0,0 +1,123 @@
+package orm
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+
+	"zombiezen.com/go/sqlite"
+	"zombiezen.com/go/sqlite/sqlitex"
+)
+
+type (
+	QueryOption func(opts *queryOpts)
+
+	queryOpts struct {
+		Transient    bool
+		Args         []interface{}
+		NamedArgs    map[string]interface{}
+		Result       interface{}
+		DecodeConfig DecodeConfig
+	}
+)
+
+func WithTransient() QueryOption {
+	return func(opts *queryOpts) {
+		opts.Transient = true
+	}
+}
+
+func WithArgs(args ...interface{}) QueryOption {
+	return func(opts *queryOpts) {
+		opts.Args = args
+	}
+}
+
+func WithNamedArgs(args map[string]interface{}) QueryOption {
+	return func(opts *queryOpts) {
+		opts.NamedArgs = args
+	}
+}
+
+func WithResult(result interface{}) QueryOption {
+	return func(opts *queryOpts) {
+		opts.Result = result
+	}
+}
+
+func WithDecodeConfig(cfg DecodeConfig) QueryOption {
+	return func(opts *queryOpts) {
+		opts.DecodeConfig = cfg
+	}
+}
+
+func RunQuery(ctx context.Context, conn *sqlite.Conn, sql string, modifiers ...QueryOption) error {
+	args := queryOpts{
+		DecodeConfig: DefaultDecodeConfig,
+	}
+
+	for _, fn := range modifiers {
+		fn(&args)
+	}
+
+	opts := &sqlitex.ExecOptions{
+		Args:  args.Args,
+		Named: args.NamedArgs,
+	}
+
+	var (
+		sliceVal    reflect.Value
+		valElemType reflect.Type
+	)
+
+	if args.Result != nil {
+		target := args.Result
+		outVal := reflect.ValueOf(target)
+		if outVal.Kind() != reflect.Ptr {
+			return fmt.Errorf("target must be a pointer, got %T", target)
+		}
+
+		sliceVal = reflect.Indirect(outVal)
+		if !sliceVal.IsValid() || sliceVal.IsNil() {
+			newVal := reflect.Zero(outVal.Type().Elem())
+			sliceVal.Set(newVal)
+		}
+
+		kind := sliceVal.Kind()
+		if kind != reflect.Slice {
+			return fmt.Errorf("target but be pointer to slice, got %T", target)
+		}
+		valType := sliceVal.Type()
+		valElemType = valType.Elem()
+
+		opts.ResultFunc = func(stmt *sqlite.Stmt) error {
+			var currentField reflect.Value
+
+			currentField = reflect.New(valElemType)
+
+			if err := DecodeStmt(ctx, stmt, currentField.Interface(), args.DecodeConfig); err != nil {
+				return err
+			}
+
+			sliceVal = reflect.Append(sliceVal, reflect.Indirect(currentField))
+
+			return nil
+		}
+	}
+
+	var err error
+	if args.Transient {
+		err = sqlitex.ExecuteTransient(conn, sql, opts)
+	} else {
+		err = sqlitex.Execute(conn, sql, opts)
+	}
+	if err != nil {
+		return err
+	}
+
+	if args.Result != nil {
+		reflect.Indirect(reflect.ValueOf(args.Result)).Set(sliceVal)
+	}
+
+	return nil
+}