よく使う言葉ではないですが、
日常会話でこれいう場合はなんと言いますか？
因みに、Google翻訳だと
I'm glad I could have bought it if I didn't have summer pants.
となりました
「ちょうど夏用のズボンがなかったらそれを買いに行けたから良かったけどね」
I'm glad I could go buy some summer pants because I didn't have any.
I didn't have any pants to wear for the summer, so it was a good thing I was able to go buy some.
ーI'm glad I could go buy some summer pants because I didn't have any.
「夏用のズボンがなかったから買いに行けてよかった」
I'm glad I could go buy ... で「…を買いに行けてよかった」
ーI didn't have any pants to wear for the summer, so it was a good thing I was able to go buy some.
「夏用のパンツが何もなかったから、買いに行けてよかった」
it was a good thing I was able to go buy ... で「…を買いに行けてよかった」
ご参考まで！
カナダ 
