ブログにgeminiのgoogle検索groundingを使ったサイト内検索機能を作った

// functions/api/search.ts
import {
  GoogleGenAI,
  DynamicRetrievalConfigMode,
  GenerateContentConfig,
} from "@google/genai"

interface ContactBody {
  query: string
}

export interface SearchResult {
  url?: string | undefined
  summary?: string | undefined
}

const API_KEY = process.env.GATSBY_GEMINI_API_KEY
const targetSite = "blog.uni-3.app"

const generationConfig: GenerateContentConfig = {
  temperature: 0.5,
  topP: 0.0,
  topK: 40,
  maxOutputTokens: 8192,
  responseModalities: [],
  responseMimeType: "text/plain",
  systemInstruction: `"入力クエリに関する記事を${targetSite}のサイトから取得し、関連記事として要約して回答して`,
  tools: [
    {
      googleSearch: {
        dynamicRetrievalConfig: {
          dynamicThreshold: 0.0, // 必ずgroundingされる
          mode: DynamicRetrievalConfigMode.MODE_DYNAMIC,
        },
      },
    },
  ],
}

async function performSearchAndSummarize(
  searchQuery: string,
): Promise<SearchResult[]> {
  try {
    const ai = new GoogleGenAI({ apiKey: API_KEY })

    const response = await ai.models.generateContent({
      model: "gemini-2.0-flash",
      config: { ...generationConfig },
      contents: [
        `クエリ: ${searchQuery} 対象サイト: ${targetSite}`,
      ],
    })

    // parse
    const metaData = response.candidates?.[0].groundingMetadata
    if (!metaData?.groundingSupports) {
      // no valid answer
      return []
    }
    const res: SearchResult[] = metaData?.groundingSupports
      ? metaData.groundingSupports
          .filter(support => {
            const groundingIndex = support.groundingChunkIndices?.[0]!
            const web = metaData.groundingChunks?.[groundingIndex].web
            return targetSite.includes(web?.title!) // 条件を満たすもののみ
          })
          .map(support => {
            const groundingIndex = support.groundingChunkIndices?.[0]!
            const web = metaData.groundingChunks?.[groundingIndex].web
            const url = web?.uri
            return {
              url: url,
              summary: support?.segment?.text,
            }
          })
      : []
    return res
  } catch (error: any) {
    console.error("検索または要約中にエラーが発生しました:", error)
    return []
  }
}

export const onRequest = async (context: any) => {
  const url = new URL(context.request.url)
  const searchQuery = url.searchParams.get("query")
  const API_KEY = context.env.API_KEY

  if (!searchQuery) {
    return new Response(JSON.stringify({ error: "Search query is required" }), {
      status: 400,
      headers: { "Content-Type": "application/json" },
    })
  }
  try {
    const result = await performSearchAndSummarize(API_KEY, searchQuery)
    return new Response(JSON.stringify(result), {
      headers: { "Content-Type": "application/json" },
    })
  } catch (error: any) {
    console.error("Error in generate content:", error)
    return new Response(
      JSON.stringify({ error: error.message || "Internal Server Error" }),
      {
        status: 500,
        headers: { "Content-Type": "application/json" },
      },
    )
  }
}

const response = await fetch(`/api/search?query=${searchQuery}`, {
        method: "GET",
        headers: {
          "Content-Type": "application/json",
        },
      })
const data = await response.json()
setSearchResults(data)