From 8696a92c11b44d2e52f50661d7126d6be74733cb Mon Sep 17 00:00:00 2001
From: Yuya Ebihara <ebyhry@gmail.com>
Date: Sat, 9 May 2026 09:49:58 +0900
Subject: [PATCH] REST: Add pagination support for list_namespaces

---
 pyiceberg/catalog/rest/__init__.py | 43 +++++++++++++------
 tests/catalog/test_rest.py         | 69 ++++++++++++++++++++++++++++++
 2 files changed, 100 insertions(+), 12 deletions(-)

diff --git a/pyiceberg/catalog/rest/__init__.py b/pyiceberg/catalog/rest/__init__.py
index ca0ff75e8c..6c7335c86a 100644
--- a/pyiceberg/catalog/rest/__init__.py
+++ b/pyiceberg/catalog/rest/__init__.py
@@ -334,6 +334,7 @@ def _parse_endpoints(cls, v: list[str] | None) -> set[Endpoint] | None:
 
 class ListNamespaceResponse(IcebergBaseModel):
     namespaces: list[Identifier] = Field()
+    next_page_token: str | None = Field(default=None, alias="next-page-token")
 
 
 class NamespaceResponse(IcebergBaseModel):
@@ -1182,19 +1183,37 @@ def drop_namespace(self, namespace: str | Identifier) -> None:
     def list_namespaces(self, namespace: str | Identifier = ()) -> list[Identifier]:
         self._check_endpoint(Capability.V1_LIST_NAMESPACES)
         namespace_tuple = self.identifier_to_tuple(namespace)
-        response = self._session.get(
-            self.url(
-                f"{Endpoints.list_namespaces}?parent={self._encode_namespace_path(namespace_tuple)}"
-                if namespace_tuple
-                else Endpoints.list_namespaces
-            ),
-        )
-        try:
-            response.raise_for_status()
-        except HTTPError as exc:
-            _handle_non_200_response(exc, {404: NoSuchNamespaceError})
 
-        return ListNamespaceResponse.model_validate_json(response.text).namespaces
+        all_namespaces: list[Identifier] = []
+        page_token: str | None = None
+
+        while True:
+            # Build URL with pagination params
+            if namespace_tuple:
+                base_url = f"{Endpoints.list_namespaces}?parent={self._encode_namespace_path(namespace_tuple)}"
+                separator = "&"
+            else:
+                base_url = Endpoints.list_namespaces
+                separator = "?"
+
+            # Add page token if present
+            url = f"{base_url}{separator}pageToken={page_token}" if page_token else base_url
+
+            response = self._session.get(self.url(url))
+            try:
+                response.raise_for_status()
+            except HTTPError as exc:
+                _handle_non_200_response(exc, {404: NoSuchNamespaceError})
+
+            parsed = ListNamespaceResponse.model_validate_json(response.text)
+            all_namespaces.extend(parsed.namespaces)
+
+            # Check if more pages exist
+            if not parsed.next_page_token:
+                break
+            page_token = parsed.next_page_token
+
+        return all_namespaces
 
     @retry(**_RETRY_ARGS)
     def load_namespace_properties(self, namespace: str | Identifier) -> Properties:
diff --git a/tests/catalog/test_rest.py b/tests/catalog/test_rest.py
index 7977892635..94f80ff2a9 100644
--- a/tests/catalog/test_rest.py
+++ b/tests/catalog/test_rest.py
@@ -736,6 +736,75 @@ def test_list_namespace_with_parent_200(rest_mock: Mocker) -> None:
     ]
 
 
+def test_list_namespaces_paginated_200(rest_mock: Mocker) -> None:
+    # First page with next-page-token
+    rest_mock.get(
+        f"{TEST_URI}v1/namespaces",
+        json={
+            "namespaces": [["ns1"], ["ns2"]],
+            "next-page-token": "page2token",
+        },
+        status_code=200,
+        request_headers=TEST_HEADERS,
+    )
+    # Second page with next-page-token
+    rest_mock.get(
+        f"{TEST_URI}v1/namespaces?pageToken=page2token",
+        json={
+            "namespaces": [["ns3"], ["ns4"]],
+            "next-page-token": "page3token",
+        },
+        status_code=200,
+        request_headers=TEST_HEADERS,
+    )
+    # Third page without next-page-token (last page)
+    rest_mock.get(
+        f"{TEST_URI}v1/namespaces?pageToken=page3token",
+        json={
+            "namespaces": [["ns5"]],
+        },
+        status_code=200,
+        request_headers=TEST_HEADERS,
+    )
+
+    result = RestCatalog("rest", uri=TEST_URI, token=TEST_TOKEN).list_namespaces()
+    assert result == [
+        ("ns1",),
+        ("ns2",),
+        ("ns3",),
+        ("ns4",),
+        ("ns5",),
+    ]
+
+
+def test_list_namespaces_with_parent_paginated_200(rest_mock: Mocker) -> None:
+    # First page
+    rest_mock.get(
+        f"{TEST_URI}v1/namespaces?parent=accounting",
+        json={
+            "namespaces": [["accounting", "tax"]],
+            "next-page-token": "page2",
+        },
+        status_code=200,
+        request_headers=TEST_HEADERS,
+    )
+    # Second page (last)
+    rest_mock.get(
+        f"{TEST_URI}v1/namespaces?parent=accounting&pageToken=page2",
+        json={
+            "namespaces": [["accounting", "payroll"]],
+        },
+        status_code=200,
+        request_headers=TEST_HEADERS,
+    )
+
+    result = RestCatalog("rest", uri=TEST_URI, token=TEST_TOKEN).list_namespaces(("accounting",))
+    assert result == [
+        ("accounting", "tax"),
+        ("accounting", "payroll"),
+    ]
+
+
 def test_list_namespace_with_parent_404(rest_mock: Mocker) -> None:
     rest_mock.get(
         f"{TEST_URI}v1/namespaces?parent=some_namespace",