datasette.urls.table(..., format="json"), closes #1035

Also improved tests for datasette.urls and added format= to some other methods

datasette/app.py

@@ -53,6 +53,7 @@ from .utils import (
     format_bytes,
     module_from_path,
     parse_metadata,
+    path_with_format,
     resolve_env_secrets,
     sqlite3,
     to_css_class,
@@ -1285,13 +1286,16 @@ class Urls:
     def __init__(self, ds):
         self.ds = ds
 
-    def path(self, path):
+    def path(self, path, format=None):
         if path.startswith("/"):
             path = path[1:]
-        return self.ds.config("base_url") + path
+        path = self.ds.config("base_url") + path
+        if format is not None:
+            path = path_with_format(path=path, format=format)
+        return path
 
-    def instance(self):
-        return self.path("")
+    def instance(self, format=None):
+        return self.path("", format=format)
 
     def static(self, path):
         return self.path("-/static/{}".format(path))
@@ -1302,21 +1306,33 @@ class Urls:
     def logout(self):
         return self.path("-/logout")
 
-    def database(self, database):
+    def database(self, database, format=None):
         db = self.ds.databases[database]
         if self.ds.config("hash_urls") and db.hash:
-            return self.path("{}-{}".format(database, db.hash[:HASH_LENGTH]))
+            path = self.path(
+                "{}-{}".format(database, db.hash[:HASH_LENGTH]), format=format
+            )
         else:
-            return self.path(database)
+            path = self.path(database, format=format)
+        return path
 
-    def table(self, database, table):
-        return "{}/{}".format(self.database(database), urllib.parse.quote_plus(table))
+    def table(self, database, table, format=None):
+        path = "{}/{}".format(self.database(database), urllib.parse.quote_plus(table))
+        if format is not None:
+            path = path_with_format(path=path, format=format)
+        return path
 
-    def query(self, database, query):
-        return "{}/{}".format(self.database(database), urllib.parse.quote_plus(query))
+    def query(self, database, query, format=None):
+        path = "{}/{}".format(self.database(database), urllib.parse.quote_plus(query))
+        if format is not None:
+            path = path_with_format(path=path, format=format)
+        return path
 
-    def row(self, database, table, row_path):
-        return "{}/{}".format(self.table(database, table), row_path)
+    def row(self, database, table, row_path, format=None):
+        path = "{}/{}".format(self.table(database, table), row_path)
+        if format is not None:
+            path = path_with_format(path=path, format=format)
+        return path
 
     def row_blob(self, database, table, row_path, column):
         return self.table(database, table) + "/{}.blob?_blob_column={}".format(

datasette/utils/__init__.py

@@ -678,9 +678,11 @@ async def resolve_table_and_format(
     return table_and_format, None
 
 
-def path_with_format(request, format, extra_qs=None, replace_format=None):
+def path_with_format(
+    *, request=None, path=None, format=None, extra_qs=None, replace_format=None
+):
     qs = extra_qs or {}
-    path = request.path
+    path = request.path if request else path
     if replace_format and path.endswith(".{}".format(replace_format)):
         path = path[: -(1 + len(replace_format))]
     if "." in path:
@@ -689,11 +691,11 @@ def path_with_format(request, format, extra_qs=None, replace_format=None):
         path = "{}.{}".format(path, format)
     if qs:
         extra = urllib.parse.urlencode(sorted(qs.items()))
-        if request.query_string:
+        if request and request.query_string:
             path = "{}?{}&{}".format(path, request.query_string, extra)
         else:
             path = "{}?{}".format(path, extra)
-    elif request.query_string:
+    elif request and request.query_string:
         path = "{}?{}".format(path, request.query_string)
     return path
 

datasette/views/base.py

@@ -333,8 +333,8 @@ class DataView(BaseView):
                                         cell = self.ds.absolute_url(
                                             request,
                                             path_with_format(
-                                                request,
-                                                "blob",
+                                                request=request,
+                                                format="blob",
                                                 extra_qs={
                                                     "_blob_column": column,
                                                     "_blob_hash": hashlib.sha256(
@@ -535,11 +535,13 @@ class DataView(BaseView):
                 it_can_render = await await_me_maybe(it_can_render)
                 if it_can_render:
                     renderers[key] = path_with_format(
-                        request, key, {**url_labels_extra}
+                        request=request, format=key, extra_qs={**url_labels_extra}
                     )
 
             url_csv_args = {"_size": "max", **url_labels_extra}
-            url_csv = path_with_format(request, "csv", url_csv_args)
+            url_csv = path_with_format(
+                request=request, format="csv", extra_qs=url_csv_args
+            )
             url_csv_path = url_csv.split("?")[0]
             context = {
                 **data,

datasette/views/database.py

@@ -346,8 +346,8 @@ class QueryView(DataView):
                             )
                         elif isinstance(display_value, bytes):
                             blob_url = path_with_format(
-                                request,
-                                "blob",
+                                request=request,
+                                format="blob",
                                 extra_qs={
                                     "_blob_column": column,
                                     "_blob_hash": hashlib.sha256(