extend blog articles endpoint to allow to query for tags

Signed-off-by: Tobias Erbshäußer <tobias@tesoft.dev>

backend/blog.go

@@ -155,6 +155,7 @@ func (h *ApiHandler) ServeBlogGet(writer http.ResponseWriter, request *http.Requ
 	var err error
 	var offset int
 	var limit int
+	tags := make([]string, 0)
 
 	offsetStr := query.Get("offset")
 	if offsetStr == "" {
@@ -178,13 +179,21 @@ func (h *ApiHandler) ServeBlogGet(writer http.ResponseWriter, request *http.Requ
 		}
 	}
 
-	articles, err := h.db.GetBlogArticles(IsAuthorized(request), offset, limit)
+	tagsStr := query.Get("tags")
+	if tagsStr != "" {
+		tags = strings.Split(tagsStr, ",")
+	}
+
+	articles, total, err := h.db.GetBlogArticles(IsAuthorized(request), offset, limit, tags)
 	if err != nil {
 		WriteError(writer, http.StatusInternalServerError, "failed to query database", err)
 		return
 	}
 
-	WriteResponse(writer, http.StatusOK, articles)
+	WriteResponse(writer, http.StatusOK, map[string]interface{}{
+		"articles": articles,
+		"total":    total,
+	})
 }
 
 func (h *ApiHandler) ServeBlogPut(writer http.ResponseWriter, request *http.Request) {

backend/db.go

@@ -8,6 +8,7 @@ import (
 	"log"
 	"slices"
 	"strconv"
+	"strings"
 	"time"
 
 	_ "github.com/mattn/go-sqlite3"
@@ -134,29 +135,53 @@ func (db *Database) CreateBlogArticle() (int64, func(*Article) error, error) {
 	}, err
 }
 
-func (db *Database) GetBlogArticles(showAll bool, offset int, limit int) ([]ArticleProperties, error) {
+func (db *Database) GetBlogArticles(showAll bool, offset int, limit int, tags []string) ([]ArticleProperties, int64, error) {
-	inner := "SELECT id FROM blog_article"
+	filters := make([]string, 0)
+	filterArgs := make([]interface{}, 0)
+
 	if !showAll {
-		inner = inner + " WHERE status = " + strconv.Itoa(ArticleStatusPublished)
+		filters = append(filters, "blog_article.status = ?")
+		filterArgs = append(filterArgs, ArticleStatusPublished)
 	}
-	inner = inner + " ORDER BY date DESC LIMIT ? OFFSET ?"
+	if len(tags) > 0 {
-	outer := "SELECT blog_article.id, blog_article.status, blog_article.title, blog_article.date, blog_article.modification_date, blog_tag.name" +
+		filters = append(filters, "blog_tag.name IN (?"+strings.Repeat(", ?", len(tags)-1)+") GROUP BY blog_article.id HAVING COUNT(DISTINCT blog_tag.id) = ?")
-		" FROM blog_article" +
+		for _, tag := range tags {
-		" LEFT JOIN blog_article_to_tag ON blog_article.id = blog_article_to_tag.article_id" +
+			filterArgs = append(filterArgs, tag)
-		" LEFT JOIN blog_tag ON blog_article_to_tag.tag_id = blog_tag.id" +
+		}
-		" WHERE blog_article.id IN (" + inner + ")" +
+		filterArgs = append(filterArgs, len(tags))
-		" ORDER BY blog_article.date DESC, blog_article.id"
+	}
+
+	filter := ""
+	if len(filters) > 0 {
+		filter = " WHERE " + strings.Join(filters, " AND ")
+	}
+
+	joins := " LEFT JOIN blog_article_to_tag ON blog_article.id = blog_article_to_tag.article_id" +
+		" LEFT JOIN blog_tag ON blog_article_to_tag.tag_id = blog_tag.id"
+
+	args := make([]interface{}, 0, len(filterArgs)*2+2)
+	args = append(args, filterArgs...)
+	args = append(args, filterArgs...)
+	args = append(args, limit)
+	args = append(args, offset)
 
 	rows, err := db.db.Query(
-		outer,
+		"SELECT blog_article.id, blog_article.status, blog_article.title, blog_article.date, blog_article.modification_date, blog_tag.name,"+
-		limit,
+			" (SELECT COUNT(DISTINCT blog_article.id) FROM blog_article"+joins+filter+")"+
-		offset,
+			" FROM blog_article"+joins+
+			" WHERE blog_article.id IN ("+
+			"  SELECT blog_article.id FROM blog_article"+joins+filter+" ORDER BY date DESC LIMIT ? OFFSET ?"+
+			" )"+
+			" ORDER BY blog_article.date DESC, blog_article.id",
+		args...,
 	)
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
 	articles := make([]ArticleProperties, 0)
+	var total int64
+
 	for rows.Next() {
 		var id int64
 		var status ArticleStatus
@@ -164,10 +189,10 @@ func (db *Database) GetBlogArticles(showAll bool, offset int, limit int) ([]Arti
 		var dateStr string
 		var modificationDateStr *string
 		var tag *string
-		err := rows.Scan(&id, &status, &title, &dateStr, &modificationDateStr, &tag)
+		err := rows.Scan(&id, &status, &title, &dateStr, &modificationDateStr, &tag, &total)
 		if err != nil {
 			_ = rows.Close()
-			return nil, err
+			return nil, 0, err
 		}
 
 		if tag != nil && len(articles) > 0 && articles[len(articles)-1].Id == id {
@@ -199,10 +224,10 @@ func (db *Database) GetBlogArticles(showAll bool, offset int, limit int) ([]Arti
 
 	err = rows.Close()
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
-	return articles, nil
+	return articles, total, nil
 }
 
 func (db *Database) GetBlogArticle(showAll bool, id int64) (*Article, error) {