feat(blog) add implementation for table meta

backend/src/api/post/refresh.rs

@@ -147,6 +147,7 @@ async fn build_post_idx(
     if build_post_idx::hash(db_connection, post_id, hash).await? {
         build_post_idx::base(db_connection, &post, post_id, meta).await?;
         build_post_idx::tag(db_connection, post_id, meta).await?;
+        build_post_idx::meta(db_connection, post_id, meta).await?;
     }
 
     Ok(())

backend/src/api/post/utils/build_post_idx.rs

@@ -212,3 +212,65 @@ INSERT INTO Hash (post_id, hash) VALUES ($1, $2)
         }),
     }
 }
+
+pub async fn meta(db_connection: &PgPool, post_id: Uuid, meta: &Value) -> Result<(), PostIdxError> {
+    if let Err(e) = query(
+format!(
+        r"
+DO
+$$
+    DECLARE
+        _post_id        UUID  := '{}';
+        _meta_cols      JSONB := '{}';
+        _exists         BOOLEAN;
+        _col_name       TEXT;
+        _col_value      TEXT;
+        _sql            TEXT;
+        _insert_columns TEXT  := 'post_id';
+        _insert_values  TEXT  := quote_literal(_post_id);
+        _update_set     TEXT  := '';
+    BEGIN
+        SELECT EXISTS(SELECT 1 FROM meta WHERE post_id = _post_id) INTO _exists;
+
+        FOR _col_name, _col_value IN SELECT key, value FROM jsonb_each_text(_meta_cols)
+            LOOP
+                IF NOT EXISTS (SELECT 1
+                               FROM information_schema.columns
+                               WHERE table_name = 'meta'
+                                 AND column_name = _col_name
+                                 -- may change in the future
+                                 AND table_schema = 'public') THEN
+                    _sql := 'ALTER TABLE meta ADD COLUMN ' || quote_ident(_col_name) || ' TEXT';
+                    EXECUTE _sql;
+                END IF;
+                _insert_columns := _insert_columns || ', ' || quote_ident(_col_name);
+                _insert_values := _insert_values || ', ' || quote_literal(_col_value);
+                _update_set := _update_set || ', ' || quote_ident(_col_name) || ' = ' || quote_literal(_col_value);
+            END LOOP;
+
+        _update_set := substring(_update_set FROM 3);
+
+        IF _exists THEN
+            _sql := 'UPDATE meta SET ' || _update_set || ' WHERE post_id = ' || quote_literal(_post_id);
+            EXECUTE _sql;
+        ELSE
+            _sql := 'INSERT INTO meta (' || _insert_columns || ') VALUES (' || _insert_values || ')';
+            EXECUTE _sql;
+        END IF;
+    END;
+$$ LANGUAGE plpgsql;
+        ", post_id.to_string().as_str(), meta.to_string()
+).as_str()
+    )
+        .execute(db_connection)
+        .await {
+        Err(PostIdxError::DBWriteFailure {
+            data_desc: "post meta data".to_string(),
+            db_table: "Meta".to_string(),
+            id: post_id.to_string(),
+            err_msg: e.to_string(),
+        })
+    } else {
+        Ok(())
+    }
+}

backend/src/model/blog/meta.sql

@@ -2,3 +2,48 @@ CREATE TABLE IF NOT EXISTS Meta
 (
     post_id UUID PRIMARY KEY
 );
+
+DROP table meta;
+
+DO
+$$
+    DECLARE
+        _post_id        UUID  := 'd5a209d4-93b1-474e-8e4e-9c78d6e6e763'; -- test data
+        _meta_cols      JSONB := '{"title": " title", "tags": "example tags", "new_col1": "new_value1", "new_col3": "new_value2"}'; -- test data
+        _exists         BOOLEAN;
+        _col_name       TEXT;
+        _col_value      TEXT;
+        _sql            TEXT;
+        _insert_columns TEXT  := 'post_id';
+        _insert_values  TEXT  := quote_literal(_post_id);
+        _update_set     TEXT  := '';
+    BEGIN
+        SELECT EXISTS(SELECT 1 FROM meta WHERE post_id = _post_id) INTO _exists;
+
+        FOR _col_name, _col_value IN SELECT key, value FROM jsonb_each_text(_meta_cols)
+            LOOP
+                IF NOT EXISTS (SELECT 1
+                               FROM information_schema.columns
+                               WHERE table_name = 'meta'
+                                 AND column_name = _col_name
+                                 -- may change in the future
+                                 AND table_schema = 'public') THEN
+                    _sql := 'ALTER TABLE meta ADD COLUMN ' || quote_ident(_col_name) || ' TEXT';
+                    EXECUTE _sql;
+                END IF;
+                _insert_columns := _insert_columns || ', ' || quote_ident(_col_name);
+                _insert_values := _insert_values || ', ' || quote_literal(_col_value);
+                _update_set := _update_set || ', ' || quote_ident(_col_name) || ' = ' || quote_literal(_col_value);
+            END LOOP;
+
+        _update_set := substring(_update_set FROM 3);
+
+        IF _exists THEN
+            _sql := 'UPDATE meta SET ' || _update_set || ' WHERE post_id = ' || quote_literal(_post_id);
+            EXECUTE _sql;
+        ELSE
+            _sql := 'INSERT INTO meta (' || _insert_columns || ') VALUES (' || _insert_values || ')';
+            EXECUTE _sql;
+        END IF;
+    END;
+$$ LANGUAGE plpgsql;