v.net: Add JSON output support for nodes operation by tangelll · Pull Request #6999 · OSGeo/grass

tangelll · 2026-01-30T20:41:52Z

Description

This PR introduces JSON output support for the v.net module, specifically for the operation=nodes task. This enhancement allows users to programmatically capture network statistics (such as new node counts) for use in automated workflows and testing pipelines.

Changes

Core Logic: Integrated G_JSON support in main.c to handle structured output.
CLI Arguments: Added a new format parameter to choose between plain (default) and json.
Documentation: Updated v.net.md with usage examples and guidelines for JSON output.
Testing: Added an automated Python test case in testsuite/test_v_net.py to ensure output consistency.

How to Test

To verify the implementation, you can use the North Carolina sample dataset.

Manual Verification:

# Copy sample data
g.copy vector=streets_wake,my_streets

# Run the module with JSON format for nreport
testsuite % v.net input=my_streets_ready operation=nreport nlayer=2 format=json

#Run the module with JSON format for report
v.net input=streets output=test_vnet operation=report  format=json

Expected JSON Output :

[
{
"line_cat": 49599,
"start_node_cat": -1,
"end_node_cat": -1
},
...
]

Automated Test Suite: Run the newly added test case:

python3 vector/v.net/testsuite/test_v_net.py

Copying features...
100%
Building topology for vector map test_vnet@PERMANENT...
Registering primitives...
40000
Copying attributes...
Building topology for vector map test_vnet@PERMANENT...
Registering primitives...
50000
v.net complete. 323 lines (network arcs) written to output.

.
Copying features...
100%
Building topology for vector map test_vnet@PERMANENT...
Registering primitives...
40000
Copying attributes...
Building topology for vector map test_vnet@PERMANENT...
Registering primitives...
50000
v.net complete. 156 lines (network arcs) written to output.

.
Copying attributes...
Building topology for vector map test_vnet@PERMANENT...
Registering primitives...
90000
v.net complete. 41813 new points (nodes) written to output.

.v.net complete.
.v.net complete.
.OK

man/build_check.py

petrasovaa · 2026-01-30T21:18:07Z

vector/v.net/args.c

    opt->tucfield->required = NO;
    opt->tucfield->guisection = _("Turntable");
+
+    opt->format = G_define_option();


Use G_OPT_F_FORMAT standard option.

petrasovaa · 2026-01-30T21:21:47Z

vector/v.net/main.c

-            G_message(_("Copying attributes..."));
-            if (Vect_copy_tables(In, Out, 0))
+            if (root_object) {
+                G_json_object_set_string(root_object, "current_step",


These are messages that go to stderr, they are not expected to be in output JSON.

petrasovaa

To simplify review, could you please post the examples and the output as it was and with the changes you made? Edit the PR description.

tangelll · 2026-01-30T21:35:41Z

To simplify review, could you please post the examples and the output as it was and with the changes you made? Edit the PR description.

I’ve updated the PR and reverted the changes in the man folder. Please note that some minor formatting was automatically adjusted by my local pre-commit hooks.

petrasovaa

Thank you, several things to address:

Please fix the problems in compilation:

main.c: In function ‘main’:
main.c:62:5: warning: ‘output_format’ may be used uninitialized [-Wmaybe-uninitialized]
   62 |     parse_arguments(&opt, &afield, &nfield, &thresh, &act, output_format);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
main.c:30:33: note: ‘output_format’ was declared here
   30 |     enum { PLAIN, SHELL, JSON } output_format;
      |                                 ^~~~~~~~~~~~~

Remove the reporting of new nodes, keep the json output for operation=report and nreport only.

Drop the shell format, instead you can add CSV.

Remove any unrelated changes (e.g. you removed several empty lines).

The test misses the report/nreport case.

Thank you!

petrasovaa · 2026-02-01T04:01:34Z

vector/v.net/args.c

+    opt->format = G_define_standard_option(G_OPT_F_FORMAT);
+    opt->format->key = "format";
+    opt->format->type = TYPE_STRING;
+    opt->format->required = NO;
+    opt->format->options = "plain,shell,json";
+    opt->format->answer = "plain";
+    opt->format->description = _("Output");


These are already part of the standard option definition.

Suggested change

opt->format = G_define_standard_option(G_OPT_F_FORMAT);

opt->format->key = "format";

opt->format->type = TYPE_STRING;

opt->format->required = NO;

opt->format->options = "plain,shell,json";

opt->format->answer = "plain";

opt->format->description = _("Output");

opt->format = G_define_standard_option(G_OPT_F_FORMAT);

opt->format->required = NO;

opt->format->options = "plain,shell,json";

opt->format->answer = "plain";

opt->format->description = _("Output");

…porting from stdout. Cleaned up redundant code and added validation tests.

petrasovaa · 2026-02-06T03:35:21Z

vector/v.net/report.c

                        }
-                        fprintf(stdout, "\n");
+                        if (root_arr) {
+                            G_json_object_set_value(G_json_value_get_object(item_val), "lines", lines_val);                            G_json_array_append_value(root_arr, item_val);


Use pre-commit to automatically fix the formatting.

petrasovaa · 2026-02-06T03:40:31Z

vector/v.net/testsuite/test_v_net.py

+        except json.JSONDecodeError:
+            self.fail(f"nreport produced invalid JSON: {output}")
+
+        self.assertIsInstance(data, list, "nreport output must be a JSON array")


The tests should be more specific that just verifying type of output data.

petrasovaa · 2026-02-06T03:41:31Z

vector/v.net/v.net.md

+Generating nodes and getting the result in JSON:
+
+```sh
+v.net input=streets operation=nodes format=json -c


The example should also show the example output.

petrasovaa · 2026-02-06T03:43:10Z

vector/v.net/testsuite/test_v_net.py

+    def test_nreport_json(self):
+        """Test nreport operation JSON output"""
+        self.runModule("v.net", input="streets", output=self.network, operation="nodes")
+        output = read_command(


Use parse_command or the new Tools API:
https://grass.osgeo.org/grass-devel/manuals/python_intro.html#running-tools

tangelll added 4 commits January 30, 2026 23:18

Add JSON Output Support to v.net

11aacda

Add JSON Output Support to v.net

fbdb34e

Add JSON Output Support to v.net

4484c3b

Pre-Commit Fix

392cc19

github-actions bot added vector Related to vector data processing Python Related code is in Python C Related code is in C module docs markdown Related to markdown, markdown files tests Related to Test Suite labels Jan 30, 2026

tangelll added 2 commits January 30, 2026 23:55

Deleted Test Replaced

748816e

Removed duplicate function declaration in report.c

3c2b032

petrasovaa reviewed Jan 30, 2026

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man/build_check.py Show resolved Hide resolved

petrasovaa reviewed Jan 30, 2026

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petrasovaa requested changes Jan 30, 2026

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Reverted unintended changes in the man folder

f8cdacf

Needed fixes is done.

81cb17e

petrasovaa requested changes Feb 1, 2026

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tangelll added 2 commits February 6, 2026 01:06

Added JSON support for report/nreport and removed unnecessary node re…

b02f64c

…porting from stdout. Cleaned up redundant code and added validation tests.

pre-commit.fix

247d6b1

petrasovaa reviewed Feb 6, 2026

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v.net: Add JSON output support for nodes operation#6999

v.net: Add JSON output support for nodes operation#6999
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Description

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How to Test

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