feat: add JSON-LD Place structured data to city pages (#120)

src/app/city/[slug]/page.tsx

@@ -8,6 +8,7 @@ import {
   placesByType,
 } from "@/lib/city-pages";
 import { getPlaces } from "@/lib/places";
+import { placeJsonLdScript } from "@/lib/jsonld";
 import { humanizeCity, PLACE_TYPE_LABELS } from "@/lib/types";
 import { Button } from "@/components/ui/button";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
@@ -64,6 +65,15 @@ export default async function CityPage({ params }: CityPageProps) {
 
   return (
     <PageContainer>
+      {page.places.map((place) => (
+        <script
+          key={place.id}
+          type="application/ld+json"
+          // One schema.org/Place node per place: real fields only, no
+          // placeholders, geo omitted when coordinates are missing (#120).
+          dangerouslySetInnerHTML={{ __html: placeJsonLdScript(place) }}
+        />
+      ))}
       <p className="kicker">Places in</p>
       <h1 className="mt-3 font-heading text-3xl font-bold tracking-tight sm:text-4xl">
         {name}

src/lib/jsonld.test.ts

@@ -0,0 +1,112 @@
+import { describe, expect, it } from "vitest";
+
+import { placeJsonLd, placeJsonLdScript, schemaOrgType } from "@/lib/jsonld";
+import { site } from "@/lib/site";
+import type { Place } from "@/lib/types";
+
+function place(overrides: Partial<Place> = {}): Place {
+  return {
+    id: "mum-library-01",
+    name: "David Sassoon Library",
+    type: "library",
+    city: "mumbai",
+    lat: 18.9674,
+    lng: 72.8339,
+    address: "Fort, Mumbai 400001",
+    gmaps_link: "https://maps.google.com/?q=18.9674,72.8339",
+    added_by: "test",
+    ...overrides,
+  };
+}
+
+describe("schemaOrgType", () => {
+  it("maps library, gov_offices and airport to their specific subtypes", () => {
+    expect(schemaOrgType("library")).toBe("Library");
+    expect(schemaOrgType("gov_offices")).toBe("GovernmentOffice");
+    expect(schemaOrgType("airport")).toBe("Airport");
+  });
+
+  it("falls back to Place for types without a genuine schema.org match", () => {
+    expect(schemaOrgType("sat_centre")).toBe("Place");
+    expect(schemaOrgType("foreign_lang_exam_centre")).toBe("Place");
+    expect(schemaOrgType("other_places")).toBe("Place");
+  });
+});
+
+describe("placeJsonLd", () => {
+  it("emits name, address, geo and the map deep link", () => {
+    expect(placeJsonLd(place())).toEqual({
+      "@context": "https://schema.org",
+      "@type": "Library",
+      name: "David Sassoon Library",
+      url: `${site.url}/map?place=mum-library-01`,
+      address: "Fort, Mumbai 400001",
+      geo: {
+        "@type": "GeoCoordinates",
+        latitude: 18.9674,
+        longitude: 72.8339,
+      },
+    });
+  });
+
+  it("URL-encodes the place id in the deep link", () => {
+    const p = place({ id: "navi_mumbai-sat_centre-02" });
+    expect(placeJsonLd(p).url).toBe(
+      `${site.url}/map?place=navi_mumbai-sat_centre-02`,
+    );
+  });
+
+  it("uses the specific subtype when the record genuinely is one", () => {
+    expect(placeJsonLd(place({ type: "gov_offices" }))["@type"]).toBe(
+      "GovernmentOffice",
+    );
+    expect(placeJsonLd(place({ type: "airport" }))["@type"]).toBe("Airport");
+    expect(placeJsonLd(place({ type: "sat_centre" }))["@type"]).toBe("Place");
+  });
+
+  it("omits address when the record has none instead of emitting a placeholder", () => {
+    const node = placeJsonLd(place({ address: undefined }));
+    expect(node).not.toHaveProperty("address");
+  });
+
+  it("omits geo when coordinates are missing instead of emitting nulls", () => {
+    const withoutLat = ({ ...place(), lat: undefined } as unknown) as Place;
+    expect(placeJsonLd(withoutLat)).not.toHaveProperty("geo");
+    const withoutLng = ({ ...place(), lng: undefined } as unknown) as Place;
+    expect(placeJsonLd(withoutLng)).not.toHaveProperty("geo");
+  });
+
+  it("omits geo when a coordinate is not a finite number", () => {
+    expect(placeJsonLd(place({ lat: NaN, lng: 72.8339 }))).not.toHaveProperty(
+      "geo",
+    );
+    expect(placeJsonLd(place({ lat: 18.9674, lng: Infinity }))).not.toHaveProperty(
+      "geo",
+    );
+  });
+
+  it("emits only real dataset fields — no invented values", () => {
+    const node = placeJsonLd(place());
+    expect(Object.keys(node).sort()).toEqual([
+      "@context",
+      "@type",
+      "address",
+      "geo",
+      "name",
+      "url",
+    ]);
+  });
+});
+
+describe("placeJsonLdScript", () => {
+  it("serializes the node as JSON", () => {
+    const script = placeJsonLdScript(place());
+    expect(JSON.parse(script)).toEqual(placeJsonLd(place()));
+  });
+
+  it("escapes < so a name can never break out of the script tag", () => {
+    const script = placeJsonLdScript(place({ name: "A <b>Library</b>" }));
+    expect(script).not.toContain("</");
+    expect(script).toContain("\\u003c");
+  });
+});

src/lib/jsonld.ts

@@ -0,0 +1,63 @@
+import { site } from "@/lib/site";
+import type { Place } from "@/lib/types";
+
+/**
+ * The schema.org type for a place, choosing a specific subtype where one
+ * genuinely fits (a `Library` really is a schema.org Library, etc.) and
+ * falling back to the generic `Place` everywhere else.
+ */
+export function schemaOrgType(type: Place["type"]): string {
+  switch (type) {
+    case "library":
+      return "Library";
+    case "gov_offices":
+      return "GovernmentOffice";
+    case "airport":
+      return "Airport";
+    default:
+      return "Place";
+  }
+}
+
+/**
+ * Build the schema.org/Place JSON-LD graph node for one place.
+ *
+ * Only fields the dataset actually holds are emitted — never placeholders.
+ * `geo` is omitted entirely when coordinates are missing or unusable, and
+ * `address` is omitted when the record has none, so the structured data can
+ * never misrepresent the page.
+ */
+export function placeJsonLd(place: Place): Record<string, unknown> {
+  const node: Record<string, unknown> = {
+    "@context": "https://schema.org",
+    "@type": schemaOrgType(place.type),
+    name: place.name,
+    // Deep link straight to the place pin on the map.
+    url: `${site.url}/map?place=${encodeURIComponent(place.id)}`,
+  };
+
+  if (place.address) {
+    node.address = place.address;
+  }
+
+  const hasLat = typeof place.lat === "number" && Number.isFinite(place.lat);
+  const hasLng = typeof place.lng === "number" && Number.isFinite(place.lng);
+  if (hasLat && hasLng) {
+    node.geo = {
+      "@type": "GeoCoordinates",
+      latitude: place.lat,
+      longitude: place.lng,
+    };
+  }
+
+  return node;
+}
+
+/**
+ * The JSON payload for a `<script type="application/ld+json">` block.
+ * `<` is escaped so a name containing `</script>` can never terminate the
+ * block early and inject markup.
+ */
+export function placeJsonLdScript(place: Place): string {
+  return JSON.stringify(placeJsonLd(place)).replace(/</g, "\\u003c");
+}