のに being used in a positive sense?


I read an example sentence with the word 検索

> 索引があるので **検索** するのに便利だ

I know のに can show disappointment. Here, however, I think it's being used in a
positive sense?

> Because index(es) exist(s), searching up (things) is convenient/easy.

But how is this のに used here?




This is not the particle のに meaning "even though", "despite", which is
composed of
準体助詞「の」＋接続助詞「に」([デジタル大辞泉（小学館）](https://dictionary.goo.ne.jp/word/%E3%81%AE%E3%81%AB/))

This is 準体助詞「の」＋ **格助詞** 「に」. (ibid.) The difference is significant, because
with a 格助詞 (case particle) what this のに does is first turn the preceding
phrase into a noun and semantically connect it with what follows. に being a
格助詞 signifies the semantic relation between the verb phrase(or adjective
phrase)-turned-noun and the following phrase.

This happens to parallel how certain prepositions work in English.

> *The tool is convenient for do searches (ungrammatical)

So turn the part after the preposition "for" into a gerund and we get

> The tool is convenient for doing searches

voila!

> [検索するの]に便利だ

This means: "convenient for doing searches"




This is not the particle のに meaning "even though", "despite", which is
composed of
準体助詞「の」＋接続助詞「に」([デジタル大辞泉（小学館）](https://dictionary.goo.ne.jp/word/%E3%81%AE%E3%81%AB/))

This is 準体助詞「の」＋ **格助詞** 「に」. (ibid.) The difference is significant, because
with a 格助詞 (case particle) what this のに does is first turn the preceding
phrase into a noun and semantically connect it with what follows. に being a
格助詞 signifies the semantic relation between the verb phrase(or adjective
phrase)-turned-noun and the following phrase.

This happens to parallel how certain prepositions work in English.

> *The tool is convenient for do searches (ungrammatical)

So turn the part after the preposition "for" into a gerund and we get

> The tool is convenient for doing searches

voila!

> [検索するの]に便利だ

This means: "convenient for doing searches"

