eh?

lib/ch/row_binary.ex

@@ -698,6 +698,20 @@ defmodule Ch.RowBinary do
   defp utf8_size(codepoint) when codepoint <= 0xFFFF, do: 3
   defp utf8_size(codepoint) when codepoint <= 0x10FFFF, do: 4
 
+  @compile inline: [decode_json_decode_rows: 5]
+
+  for {pattern, size} <- varints do
+    defp decode_json_decode_rows(
+           <<unquote(pattern), s::size(unquote(size))-bytes, bin::bytes>>,
+           types_rest,
+           row,
+           rows,
+           types
+         ) do
+      decode_rows(types_rest, bin, [:json.decode(s) | row], rows, types)
+    end
+  end
+
   @compile inline: [decode_binary_decode_rows: 5]
 
   for {pattern, size} <- varints do
@@ -867,7 +881,7 @@ defmodule Ch.RowBinary do
         decode_rows(types_rest, bin, [Date.add(@epoch_date, d) | row], rows, types)
 
       :json ->
-        raise ArgumentError, "JSON type is not supported for decoding: #{inspect(bin)}"
+        decode_json_decode_rows(bin, types_rest, row, rows, types)
 
       {:datetime, timezone} ->
         <<s::32-little, bin::bytes>> = bin

test/ch/connection_test.exs

@@ -568,12 +568,55 @@ defmodule Ch.ConnectionTest do
               }} = Ch.query(conn, "SELECT * FROM t_uuid ORDER BY y")
     end
 
+    # TODO non utf8
+    test "read json as string", %{conn: conn} do
+      assert Ch.query!(conn, ~s|select '{"a":42}'::JSON|, [],
+               settings: [
+                 enable_json_type: 1,
+                 output_format_binary_write_json_as_string: 1
+               ]
+             ).rows == [[%{"a" => "42"}]]
+    end
+
+    test "write->read json as string", %{conn: conn} do
+      Ch.query!(conn, "CREATE TABLE test_write_json(json JSON) ENGINE = Memory", [],
+        settings: [
+          enable_json_type: 1
+        ]
+      )
+
+      rowbinary =
+        Ch.RowBinary.encode_rows(
+          [
+            [:json.encode(%{"a" => 42})],
+            [:json.encode(%{"b" => 10})]
+          ],
+          _types = [:string]
+        )
+
+      Ch.query!(conn, ["insert into test_write_json(json) format RowBinary\n" | rowbinary], [],
+        settings: [
+          enable_json_type: 1,
+          input_format_binary_read_json_as_string: 1
+        ]
+      )
+
+      assert Ch.query!(conn, "select json from test_write_json", [],
+               settings: [
+                 enable_json_type: 1,
+                 output_format_binary_write_json_as_string: 1
+               ]
+             ).rows ==
+               [[%{"a" => "42"}], [%{"b" => "10"}]]
+    end
+
     # https://clickhouse.com/docs/en/sql-reference/data-types/newjson
     # https://clickhouse.com/docs/en/integrations/data-formats/json/overview
     # https://clickhouse.com/blog/a-new-powerful-json-data-type-for-clickhouse
     # https://clickhouse.com/blog/json-bench-clickhouse-vs-mongodb-elasticsearch-duckdb-postgresql
     # https://github.com/ClickHouse/ClickHouse/pull/70288
     # https://github.com/ClickHouse/ClickHouse/blob/master/src/Core/TypeId.h
+    @tag :skip
     test "json", %{conn: conn} do
       settings = [enable_json_type: 1]