perf(posts): add optional pagination to get_posts_by_tag, fix total count
- get_posts_by_tag 现接受 page/per_page 可选参数；两者均 None 时返回全部 （上限 200，用于无翻页 UI 的标签详情页），均提供时走标准分页。 - 修正 total：不再用 posts.len()，改为真实 COUNT(*)，即使被 LIMIT 截断 也返回完整计数。 - 新增 CacheKey::PostsByTagPage 分页缓存键，与不分页键 PostsByTag 共存。 - 前端 tags.rs 传 (None, None) 保持原全部展示行为。
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@ -235,53 +235,141 @@ pub async fn list_deleted_posts(
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/// 获取指定标签下的已发布文章列表。
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///
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/// 优先命中缓存；当前实现返回全部匹配文章，因此 total 用 posts.len() 计算。
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/// 分页参数为可选：
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/// - `page` 与 `per_page` 均为 `None` 时返回该标签下全部已发布文章（上限 200），
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/// 用于无分页 UI 的标签详情页。
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/// - 两者均提供时走标准分页（经 `clamp_pagination` 钳制）。
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/// 结果缓存于按标签的分页键空间。
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#[server(GetPostsByTag, "/api")]
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pub async fn get_posts_by_tag(tag_name: String) -> Result<PostListResponse, ServerFnError> {
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pub async fn get_posts_by_tag(
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tag_name: String,
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page: Option<i32>,
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per_page: Option<i32>,
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) -> Result<PostListResponse, ServerFnError> {
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#[cfg(feature = "server")]
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{
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if let Some((cached_posts, cached_total)) = crate::cache::get_posts_by_tag(&tag_name).await
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{
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return Ok(PostListResponse {
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posts: cached_posts,
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total: cached_total,
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});
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}
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// 仅当两个分页参数都提供时才走分页路径；任一为 None 视为不分页。
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let (page, per_page) = match (page, per_page) {
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(Some(p), Some(pp)) => (Some(p), Some(pp)),
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_ => (None, None),
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};
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let client = get_conn().await.map_err(AppError::db_conn)?;
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// 通过 JOIN 筛选含目标标签的已发布文章，并聚合该文章的所有标签。
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let rows = client
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.query(
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"SELECT
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p.id, p.author_id, p.title, p.slug, p.summary, p.status,
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p.published_at, p.created_at, p.updated_at, p.cover_image,
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p.word_count, p.reading_time,
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COALESCE(array_agg(t2.name) FILTER (WHERE t2.name IS NOT NULL), '{}') as tags
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FROM posts p
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JOIN post_tags pt ON p.id = pt.post_id
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JOIN tags t ON pt.tag_id = t.id
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LEFT JOIN post_tags pt2 ON p.id = pt2.post_id
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LEFT JOIN tags t2 ON pt2.tag_id = t2.id
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WHERE t.name = $1 AND p.status = 'published' AND p.deleted_at IS NULL
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GROUP BY p.id
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ORDER BY p.published_at DESC
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LIMIT 200",
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&[&tag_name],
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)
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.await
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.map_err(AppError::query)?;
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if let (Some(page), Some(per_page)) = (page, per_page) {
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// 分页路径：钳制参数，走分页缓存键。
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let (page, per_page) = clamp_pagination(page, per_page);
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let cache_key = crate::cache::CacheKey::PostsByTagPage {
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tag: tag_name.clone(),
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page,
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per_page,
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};
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if let Some((cached_posts, cached_total)) =
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crate::cache::get_posts_by_tag_paged(&cache_key).await
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{
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return Ok(PostListResponse {
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posts: cached_posts,
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total: cached_total,
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});
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}
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let mut posts = Vec::new();
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for row in &rows {
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posts.push(row_to_post_list_item(row));
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// 标签下已发布文章总数。
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let total: i64 = client
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.query_one(
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"SELECT COUNT(*) FROM posts p
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JOIN post_tags pt ON p.id = pt.post_id
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JOIN tags t ON pt.tag_id = t.id
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WHERE t.name = $1 AND p.status = 'published' AND p.deleted_at IS NULL",
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&[&tag_name],
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)
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.await
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.map_err(AppError::query)?
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.get(0);
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let offset = ((page - 1).max(0) as i64) * (per_page as i64);
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let limit = per_page as i64;
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let rows = client
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.query(
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"SELECT
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p.id, p.author_id, p.title, p.slug, p.summary, p.status,
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p.published_at, p.created_at, p.updated_at, p.cover_image,
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p.word_count, p.reading_time,
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COALESCE(array_agg(t2.name) FILTER (WHERE t2.name IS NOT NULL), '{}') as tags
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FROM posts p
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JOIN post_tags pt ON p.id = pt.post_id
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JOIN tags t ON pt.tag_id = t.id
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LEFT JOIN post_tags pt2 ON p.id = pt2.post_id
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LEFT JOIN tags t2 ON pt2.tag_id = t2.id
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WHERE t.name = $1 AND p.status = 'published' AND p.deleted_at IS NULL
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GROUP BY p.id
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ORDER BY p.published_at DESC
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LIMIT $2 OFFSET $3",
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&[&tag_name, &limit, &offset],
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)
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.await
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.map_err(AppError::query)?;
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let mut posts = Vec::new();
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for row in &rows {
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posts.push(row_to_post_list_item(row));
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}
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crate::cache::set_posts_by_tag_paged(&cache_key, posts.clone(), total).await;
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Ok(PostListResponse { posts, total })
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} else {
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// 不分页路径：返回全部（上限 200），用于无翻页 UI 的标签详情页。
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if let Some((cached_posts, cached_total)) =
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crate::cache::get_posts_by_tag(&tag_name).await
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{
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return Ok(PostListResponse {
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posts: cached_posts,
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total: cached_total,
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});
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}
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// 真实总数（即使被 LIMIT 截断也返回完整计数）。
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let total: i64 = client
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.query_one(
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"SELECT COUNT(*) FROM posts p
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JOIN post_tags pt ON p.id = pt.post_id
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JOIN tags t ON pt.tag_id = t.id
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WHERE t.name = $1 AND p.status = 'published' AND p.deleted_at IS NULL",
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&[&tag_name],
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)
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.await
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.map_err(AppError::query)?
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.get(0);
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let rows = client
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.query(
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"SELECT
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p.id, p.author_id, p.title, p.slug, p.summary, p.status,
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p.published_at, p.created_at, p.updated_at, p.cover_image,
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p.word_count, p.reading_time,
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COALESCE(array_agg(t2.name) FILTER (WHERE t2.name IS NOT NULL), '{}') as tags
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FROM posts p
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JOIN post_tags pt ON p.id = pt.post_id
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JOIN tags t ON pt.tag_id = t.id
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LEFT JOIN post_tags pt2 ON p.id = pt2.post_id
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LEFT JOIN tags t2 ON pt2.tag_id = t2.id
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WHERE t.name = $1 AND p.status = 'published' AND p.deleted_at IS NULL
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GROUP BY p.id
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ORDER BY p.published_at DESC
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LIMIT 200",
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&[&tag_name],
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)
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.await
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.map_err(AppError::query)?;
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let mut posts = Vec::new();
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for row in &rows {
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posts.push(row_to_post_list_item(row));
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}
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// total 为真实 COUNT(*)，不再用 posts.len()。
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crate::cache::set_posts_by_tag(&tag_name, posts.clone(), total).await;
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Ok(PostListResponse { posts, total })
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}
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// 当前查询未分页，返回全部匹配文章，因此 total 等于结果长度。
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// 若后续增加分页，应改为 COUNT(*) 查询。
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let total = posts.len() as i64;
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crate::cache::set_posts_by_tag(&tag_name, posts.clone(), total).await;
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Ok(PostListResponse { posts, total })
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}
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#[cfg(not(feature = "server"))]
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16
src/cache.rs
16
src/cache.rs
@ -74,8 +74,10 @@ pub enum CacheKey {
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AllTags,
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/// 按 slug 查询的单篇文章。
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PostBySlug(String),
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/// 按标签查询的文章列表。
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/// 按标签查询的文章列表（不分页，返回全部）。
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PostsByTag(String),
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/// 按标签查询的分页文章列表。
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PostsByTagPage { tag: String, page: i32, per_page: i32 },
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/// 文章统计信息。
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PostStats,
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/// 某篇文章下的评论列表。
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@ -274,6 +276,18 @@ pub async fn set_posts_by_tag(tag: &str, posts: Vec<PostListItem>, total: i64) {
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.await;
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}
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/// 按标签+分页读取文章列表缓存。
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#[cfg(feature = "server")]
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pub async fn get_posts_by_tag_paged(key: &CacheKey) -> Option<(Vec<PostListItem>, i64)> {
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TAG_POSTS_CACHE.get(key).await
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}
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/// 按标签+分页写入文章列表缓存。
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#[cfg(feature = "server")]
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pub async fn set_posts_by_tag_paged(key: &CacheKey, posts: Vec<PostListItem>, total: i64) {
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let _ = TAG_POSTS_CACHE.insert(key.clone(), (posts, total)).await;
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}
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/// 读取文章统计缓存。
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#[cfg(feature = "server")]
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pub async fn get_post_stats() -> Option<PostStats> {
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@ -6,7 +6,8 @@
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//!
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//! 数据获取：
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//! - 标签云通过 `use_server_future(list_tags)` 获取全部标签信息。
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//! - 标签详情通过 `use_server_future` 调用 `get_posts_by_tag(tag)` 获取该标签下的文章列表。
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//! - 标签详情通过 `use_server_future` 调用 `get_posts_by_tag(tag, None, None)`
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//! 获取该标签下的全部已发布文章（不分页）。
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//! 在 `wasm32` 目标下，这些 server function 的函数体被替换为向服务端端点发起 HTTP POST 请求的客户端存根；
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//! 实际的数据库访问逻辑仅在 `feature = "server"` 启用时运行。
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@ -109,7 +110,7 @@ pub fn TagDetail(tag: String) -> Element {
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/// 成功时渲染文章总数与文章卡片。
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#[component]
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fn TagDetailContent(tag: String) -> Element {
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let posts_res = use_server_future(move || get_posts_by_tag(tag.clone()))?;
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let posts_res = use_server_future(move || get_posts_by_tag(tag.clone(), None, None))?;
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// 将结果映射为 (posts, total) 形式以便渲染。
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let posts_data = posts_res.read().as_ref().map(|r| match r {
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