fix: support deferred path params for empty route arg values

Author: Frank-III

src/index.ts

@@ -114,6 +114,22 @@ function withContextSignal(
     }
 }
 
+function resolvePathSegmentFromCallArg(body: unknown): string | undefined {
+    if (typeof body !== 'object' || body === null) return undefined
+
+    const entries = Object.entries(body as Record<string, unknown>)
+    if (entries.length === 0) return undefined
+
+    const [paramName, paramValue] = entries[0]
+
+    // Keep dynamic placeholder when call-site intentionally passes an empty value.
+    if (paramValue === '' || paramValue == null) {
+        return `:${paramName}`
+    }
+
+    return String(paramValue)
+}
+
 interface ProxyContext {
     raw: any
     prefix: QueryKey
@@ -288,9 +304,9 @@ function createEdenTQProxy(
             )
         },
         apply(_, __, [body]) {
-            if (typeof body === 'object' && body !== null) {
-                const paramValue = Object.values(body)[0] as string
-                return createEdenTQProxy(ctx, [...paths, paramValue])
+            const paramSegment = resolvePathSegmentFromCallArg(body)
+            if (paramSegment !== undefined) {
+                return createEdenTQProxy(ctx, [...paths, paramSegment])
             }
             return createEdenTQProxy(ctx, paths)
         }
@@ -400,9 +416,9 @@ function createEdenTQUtilsProxy(
             )
         },
         apply(_, __, [body]) {
-            if (typeof body === 'object' && body !== null) {
-                const paramValue = Object.values(body)[0] as string
-                return createEdenTQUtilsProxy(ctx, [...paths, paramValue])
+            const paramSegment = resolvePathSegmentFromCallArg(body)
+            if (paramSegment !== undefined) {
+                return createEdenTQUtilsProxy(ctx, [...paths, paramSegment])
             }
             return createEdenTQUtilsProxy(ctx, paths)
         }

test/tanstack-query-advanced.test.ts

@@ -234,6 +234,17 @@ describe('EdenTQ Utils', () => {
         expect(data).toEqual({ id: '42', name: 'John' })
     })
 
+    it('supports deferred params in utils route calls', async () => {
+        const queryClient = new QueryClient()
+        const utils = createEdenTQUtils(eden, queryClient)
+
+        const data = await utils.user({ id: '' }).get.ensureData({
+            params: { id: 'deferred-42' }
+        })
+
+        expect(data).toEqual({ id: 'deferred-42', name: 'John' })
+    })
+
     it('cancel cancels in-flight queries', async () => {
         const queryClient = new QueryClient()
         const utils = createEdenTQUtils(eden, queryClient)

test/tanstack-query-real-world.test.ts

@@ -142,6 +142,25 @@ describe('Real-world API patterns', () => {
 
             expect(options.queryKey).toEqual(['cases', caseId, 'share-links'])
         })
+
+        it('supports deferred path params when placeholder value is empty', async () => {
+            const caseId = 'case-deferred-query'
+
+            const options = eden.cases({ id: '' })['share-links'].get.queryOptions({
+                params: { id: caseId }
+            })
+
+            expect(options.queryKey).toEqual([
+                'eden',
+                'get',
+                ['cases', ':id', 'share-links'],
+                { id: caseId },
+                null
+            ])
+
+            const result = await options.queryFn()
+            expect(result.data[0].url).toContain(`/${caseId}/`)
+        })
     })
 
     describe('Create Share Link Mutation', () => {
@@ -177,6 +196,19 @@ describe('Real-world API patterns', () => {
                 contact: { id: string; email: string | null; name: string } | null
             }>()
         })
+
+        it('uses mutation params when placeholder value is empty', async () => {
+            const caseId = 'case-deferred-mutation'
+
+            const options = eden.cases({ id: '' })['share-link'].post.mutationOptions()
+            const result = await options.mutationFn({
+                params: { id: caseId },
+                body: { expiresInDays: 7 }
+            })
+
+            expect(result.url).toContain(`/${caseId}/`)
+            expect(result.expiresInDays).toBe(7)
+        })
     })
 
     describe('Revoke Share Link Mutation', () => {