dependent (faceted) filters: city/brand/dimension/search narrow each other

frontend/src/api.ts

@@ -21,7 +21,7 @@ async function getJson<T>(url: string): Promise<T> {
 }
 
 export const api = {
-  meta: (): Promise<Meta> => getJson<Meta>('/api/meta'),
+  meta: (f: Filters): Promise<Meta> => getJson<Meta>('/api/meta?' + buildQuery(f)),
   boards: (f: Filters): Promise<Board[]> => getJson<Board[]>('/api/boards?' + buildQuery(f)),
   bookings: (f: Filters): Promise<Booking[]> => getJson<Booking[]>('/api/bookings?' + buildQuery(f)),
 };

frontend/src/dropdown.ts

@@ -4,6 +4,8 @@
 
 export interface Dropdown {
   setValues(values: string[], label: string): void;
+  /** Replace the available options while keeping the current selection. */
+  updateValues(values: string[]): void;
   getSelected(): string[];
   onChange(fn: () => void): void;
 }
@@ -56,7 +58,12 @@ export function createDropdown(id: string): Dropdown {
     actions.appendChild(selNone);
     panel.appendChild(actions);
 
-    for (const v of allValues) {
+    // Show all available options, plus any currently-selected value that is no
+    // longer among them (so a selection made incompatible by other filters
+    // stays visible and can still be unchecked).
+    const extra = Array.from(selected).filter((v) => !allValues.includes(v));
+    const display = allValues.concat(extra);
+    for (const v of display) {
       const label = document.createElement('label');
       const cb = document.createElement('input');
       cb.type = 'checkbox';
@@ -93,6 +100,11 @@ export function createDropdown(id: string): Dropdown {
       updateBtnText();
       renderPanel();
     },
+    updateValues(values: string[]): void {
+      allValues = values;
+      updateBtnText();
+      renderPanel();
+    },
     getSelected(): string[] {
       return Array.from(selected);
     },

frontend/src/main.ts

@@ -84,17 +84,14 @@ document.addEventListener('click', (e) => {
   }
 });
 
-async function loadMeta(): Promise<void> {
-  const meta = await api.meta();
-  cityDropdown.setValues(meta.cities, 'Все города');
-  brandDropdown.setValues(meta.brands, 'Все бренды');
-  dimensionDropdown.setValues(meta.dimensions, 'Все размеры');
-}
-
 async function loadData(fit: boolean): Promise<void> {
   el.status.textContent = 'Загрузка…';
   const f = currentFilters();
-  const [boards, bookings] = await Promise.all([api.boards(f), api.bookings(f)]);
+  const [meta, boards, bookings] = await Promise.all([api.meta(f), api.boards(f), api.bookings(f)]);
+  // Dependent filters: refresh each dropdown's options (selections preserved).
+  cityDropdown.updateValues(meta.cities);
+  brandDropdown.updateValues(meta.brands);
+  dimensionDropdown.updateValues(meta.dimensions);
   lastBoards = boards;
   lastBookings = bookings;
   view.render(boards, bookings, fit, flags());
@@ -125,9 +122,11 @@ el.zoomSlider.addEventListener('input', () => {
 });
 
 async function init(): Promise<void> {
+  cityDropdown.setValues([], 'Все города');
+  brandDropdown.setValues([], 'Все бренды');
+  dimensionDropdown.setValues([], 'Все размеры');
   rebuildDecorMenu();
   view.applyLayout();
-  await loadMeta();
   await loadData(true);
   const defaultZoomIdx = 3;
   el.zoomSlider.value = String(defaultZoomIdx);

main.py

@@ -12,17 +12,33 @@ CH_URL = f"http://{CH_HOST}:{CH_PORT}/"
 
 app = FastAPI()
 
-FILTER_SQL = """
-    char_length(city) > 0
-    AND (length({cities:Array(String)}) = 0 OR city IN {cities:Array(String)})
-    AND (length({dimensions:Array(String)}) = 0 OR dimension IN {dimensions:Array(String)})
-    AND (length({brands:Array(String)}) = 0 OR brand IN {brands:Array(String)})
-    AND (
-        {search:String} = ''
-        OR positionCaseInsensitive(address, {search:String}) > 0
-        OR positionCaseInsensitive(board_id, {search:String}) > 0
-    )
-"""
+CITY_COND = "(length({cities:Array(String)}) = 0 OR city IN {cities:Array(String)})"
+DIM_COND = "(length({dimensions:Array(String)}) = 0 OR dimension IN {dimensions:Array(String)})"
+BRAND_COND = "(length({brands:Array(String)}) = 0 OR brand IN {brands:Array(String)})"
+SEARCH_COND = (
+    "({search:String} = ''"
+    " OR positionCaseInsensitive(address, {search:String}) > 0"
+    " OR positionCaseInsensitive(board_id, {search:String}) > 0)"
+)
+
+
+def build_where(city=False, dimension=False, brand=False, search=False):
+    # Faceted WHERE: include only the requested facet conditions. For the
+    # dependent-filter option lists we exclude a facet's own condition so its
+    # available values reflect the OTHER filters (all-but-self).
+    parts = ["char_length(city) > 0"]
+    if city:
+        parts.append(CITY_COND)
+    if dimension:
+        parts.append(DIM_COND)
+    if brand:
+        parts.append(BRAND_COND)
+    if search:
+        parts.append(SEARCH_COND)
+    return "\n        AND ".join(parts)
+
+
+WHERE_ALL = build_where(city=True, dimension=True, brand=True, search=True)
 
 
 async def ch_query(sql: str, params: dict):
@@ -50,18 +66,19 @@ def parse_filters(city: str, dimension: str, brand: str, search: str):
 
 
 @app.get("/api/meta")
-async def meta():
+async def meta(city: str = "", dimension: str = "", brand: str = "", search: str = ""):
+    params = parse_filters(city, dimension, brand, search)
     cities = await ch_query(
-        "SELECT DISTINCT city FROM default.pf_board WHERE char_length(city) > 0 ORDER BY city",
-        {},
-    )
-    dimensions = await ch_query(
-        "SELECT DISTINCT dimension FROM default.pf_board WHERE char_length(dimension) > 0 ORDER BY dimension",
-        {},
+        f"SELECT DISTINCT city FROM default.pf_board WHERE {build_where(dimension=True, brand=True, search=True)} AND char_length(city) > 0 ORDER BY city",
+        params,
     )
     brands = await ch_query(
-        "SELECT DISTINCT brand FROM default.pf_board WHERE char_length(brand) > 0 ORDER BY brand",
-        {},
+        f"SELECT DISTINCT brand FROM default.pf_board WHERE {build_where(city=True, dimension=True, search=True)} AND char_length(brand) > 0 ORDER BY brand",
+        params,
+    )
+    dimensions = await ch_query(
+        f"SELECT DISTINCT dimension FROM default.pf_board WHERE {build_where(city=True, brand=True, search=True)} AND char_length(dimension) > 0 ORDER BY dimension",
+        params,
     )
     return {
         "cities": [r["city"] for r in cities],
@@ -80,7 +97,7 @@ async def boards(city: str = "", dimension: str = "", brand: str = "", search: s
             argMax(city, last_activity) AS board_city,
             argMax(dimension, last_activity) AS board_dimension
         FROM default.pf_board
-        WHERE {FILTER_SQL}
+        WHERE {WHERE_ALL}
         GROUP BY board_id
         ORDER BY board_address
     """
@@ -101,7 +118,7 @@ async def bookings(city: str = "", dimension: str = "", brand: str = "", search:
             brand,
             company_name
         FROM default.pf_board
-        WHERE {FILTER_SQL}
+        WHERE {WHERE_ALL}
         ORDER BY board_id, start_date
     """
     rows = await ch_query(sql, params)