Fix: Update resource name when child span is active in store for Next.js

packages/datadog-plugin-next/src/index.js

@@ -10,10 +10,10 @@ const errorPages = new Set(['/404', '/500', '/_error', '/_not-found', '/_not-fou
 
 class NextPlugin extends ServerPlugin {
   static id = 'next'
+  #requestsBySpanId = new WeakMap()
 
   constructor (...args) {
     super(...args)
-    this._requests = new WeakMap()
     this.addSub('apm:next:page:load', message => this.pageLoad(message))
   }
 
@@ -35,7 +35,9 @@ class NextPlugin extends ServerPlugin {
 
     analyticsSampler.sample(span, this.config.measured, true)
 
-    this._requests.set(span, req)
+    // Store request by span ID to handle cases where child spans are activated
+    const spanId = span.context()._spanId
+    this.#requestsBySpanId.set(spanId, req)
 
     return { ...store, span }
   }
@@ -89,7 +91,13 @@ class NextPlugin extends ServerPlugin {
     if (!store) return
 
     const span = store.span
-    const req = this._requests.get(span)
+
+    const spanId = span.context()._spanId
+    const parentSpanId = span.context()._parentId
+
+    // Try current span first, then parent span.
+    // This handles cases where pageLoad runs in a child span context
+    const req = this.#requestsBySpanId.get(spanId) ?? this.#requestsBySpanId.get(parentSpanId)
 
     // safeguard against missing req in complicated timeout scenarios
     if (!req) return

packages/datadog-plugin-next/test/index.spec.js

@@ -277,6 +277,35 @@ describe('Plugin', function () {
               .get(`http://127.0.0.1:${port}/api/hello/world`)
               .catch(done)
           })
+
+          it('should handle child spans and still find the request object', done => {
+            agent
+              .assertSomeTraces(traces => {
+                const spans = traces[0]
+
+                const nextRequestSpan = spans.find(span => span.name === 'next.request')
+                assert.ok(nextRequestSpan, 'next.request span should exist')
+
+                assert.strictEqual(nextRequestSpan.resource, 'GET /api/hello/[name]')
+                assert.strictEqual(nextRequestSpan.meta['next.page'], '/api/hello/[name]')
+                assert.strictEqual(nextRequestSpan.meta['http.method'], 'GET')
+                assert.strictEqual(nextRequestSpan.meta['http.status_code'], '200')
+
+                const webRequestSpan = spans.find(span => span.name === 'web.request')
+                assert.ok(webRequestSpan, 'web.request span should exist')
+                assert.strictEqual(webRequestSpan.resource, 'GET /api/hello/[name]')
+
+                const childSpan = spans.find(span => span.name === 'child.operation')
+                assert.ok(childSpan, 'child span should exist')
+                assert.strictEqual(childSpan.parent_id.toString(), nextRequestSpan.span_id.toString())
+              })
+              .then(done)
+              .catch(done)
+
+            axios
+              .get(`http://127.0.0.1:${port}/api/hello/world?createChildSpan=true`)
+              .catch(done)
+          })
         })
 
         describe('for pages', () => {

packages/datadog-plugin-next/test/pages/api/hello/[name].js

@@ -2,6 +2,17 @@
 
 export default (req, res) => {
   const tracer = require('../../../../../dd-trace')
+
+  if (req.query.createChildSpan === 'true') {
+    const childSpan = tracer.startSpan('child.operation', {
+      childOf: tracer.scope().active()
+    })
+
+    tracer.scope().activate(childSpan, () => {
+      childSpan.finish()
+    })
+  }
+
   const span = tracer.scope().active()
   const name = span && span.context()._name