proposing new --format=<format> --out-file=<file.ext> feature

conan/cli/command.py

@@ -1,4 +1,5 @@
 import argparse
+import inspect
 import textwrap
 
 from conan.api.output import ConanOutput
@@ -83,19 +84,19 @@ def doc(self):
     def _format(self, parser, info, *args):
         parser_args, _ = parser.parse_known_args(*args)
 
-        default_format = "text"
-        try:
-            formatarg = parser_args.format or default_format
-        except AttributeError:
-            formatarg = default_format
+        formatarg = getattr(parser_args, "format", "text")
+        out_file = getattr(parser_args, "out_file", None)
 
         try:
             formatter = self._formatters[formatarg]
         except KeyError:
             raise ConanException("{} is not a known format. Supported formatters are: {}".format(
                 formatarg, ", ".join(self._help_formatters)))
 
-        formatter(info)
+        if out_file and "out_file" in inspect.signature(formatter).parameters.keys():
+            formatter(info, out_file=out_file)
+        else:
+            formatter(info)
 
     @staticmethod
     def _dispatch_errors(info):

conan/cli/commands/graph.py

@@ -5,7 +5,7 @@
 from conan.api.output import ConanOutput, cli_out_write, Color
 from conan.cli import make_abs_path
 from conan.cli.args import common_graph_args, validate_common_graph_args
-from conan.cli.command import conan_command, conan_subcommand
+from conan.cli.command import conan_command, conan_subcommand, OnceArgument
 from conan.cli.commands.list import prepare_pkglist_compact, print_serial
 from conan.cli.formatters.graph import format_graph_html, format_graph_json, format_graph_dot
 from conan.cli.formatters.graph.build_order_html import format_build_order_html
@@ -192,6 +192,9 @@ def graph_info(conan_api, parser, subparser, *args):
                            help="Deployer output folder, base build folder by default if not set")
     subparser.add_argument("--build-require", action='store_true', default=False,
                            help='Whether the provided reference is a build-require')
+    subparser.add_argument("--out-file", action=OnceArgument,
+                           help="Filename of the file to save the output of the formatter.")
+
     args = parser.parse_args(*args)
 
     # parameter validation

conan/cli/formatters/graph/graph.py

@@ -11,7 +11,7 @@
     BINARY_DOWNLOAD, BINARY_BUILD, BINARY_MISSING, BINARY_UPDATE
 from conans.client.graph.graph_error import GraphConflictError
 from conans.client.installer import build_id
-from conans.util.files import load
+from conans.util.files import load, save
 
 
 # FIXME: Check all this code when format_graph_[html/dot] use serialized graph
@@ -138,11 +138,15 @@ def format_graph_dot(result):
     cli_out_write(_render_graph(graph, None, template, template_folder))
 
 
-def format_graph_json(result):
+def format_graph_json(result, out_file=None):
     graph = result["graph"]
     field_filter = result.get("field_filter")
     package_filter = result.get("package_filter")
     serial = graph.serialize()
     serial = filter_graph(serial, package_filter=package_filter, field_filter=field_filter)
     json_result = json.dumps({"graph": serial}, indent=4)
+    if out_file is not None:
+        ConanOutput().info(f"Formatted output saved to '{out_file}'")
+        save(out_file, json_result)
+        return
     cli_out_write(json_result)

test/integration/command/info/info_test.py

@@ -435,3 +435,12 @@ def requirements(self):
 
     c.run("graph info . -c tools.graph:vendor=build --build='lib*'")
     c.assert_listed_binary({"lib/1.0": (NO_SETTINGS_PACKAGE_ID, "Build")})
+
+
+def test_write_formatter_to_file():
+    c = TestClient(light=True)
+    c.save({"conanfile.py":  GenConanfile("pkg", "0.1")})
+    c.run("graph info .  --format=json --out-file=graph.json")
+    assert "Formatted output saved to 'graph.json'" in c.out
+    graph = json.loads(c.load("graph.json"))
+    assert len(graph["graph"]["nodes"]) == 1