g.list: Add JSON support #5921

NishantBansal2003 · 2025-06-20T17:44:49Z

This PR adds JSON support to the g.list module. The JSON output looks like:

[
    {
        "mapset": "test_1",
        "name": "raster_test_1",
        "type": "raster",
        "fullname": "raster_test_1@test_1"
    },
    {
        "mapset": "test_1",
        "name": "vector_test_1",
        "type": "vector",
        "fullname": "vector_test_1@test_1"
    }
]

This PR includes the following changes:

Adds a format option with plain, shell, and json modes for output formatting.
The flags -m and -t apply only when format=shell.
The flag -p is deprecated; use format=plain instead. The flag -f is also deprecated.
Adds tests covering each of the new formats.
Adds a Python example to the documentation for parsing JSON output.

Signed-off-by: Nishant Bansal <[email protected]>

petrasovaa

Looks good, just couple minor points.

petrasovaa · 2025-06-23T14:29:53Z

general/g.list/list.c

+            G_json_object_set_string(map_object, "mapset", el[i].mapset);
+            G_json_object_set_string(map_object, "name", el[i].name);
+            G_json_object_set_string(map_object, "type", el[i].type);
+            G_json_object_set_string(map_object, "fullname", fullname);


Let's switch the order to have name, mapset, type, fullname:

Suggested change

G_json_object_set_string(map_object, "mapset", el[i].mapset);

G_json_object_set_string(map_object, "name", el[i].name);

G_json_object_set_string(map_object, "type", el[i].type);

G_json_object_set_string(map_object, "fullname", fullname);

G_json_object_set_string(map_object, "mapset", el[i].mapset);

G_json_object_set_string(map_object, "name", el[i].name);

G_json_object_set_string(map_object, "type", el[i].type);

G_json_object_set_string(map_object, "fullname", fullname);

petrasovaa · 2025-06-23T14:49:52Z

general/g.list/g.list.md

+```python
+import grass.script as gs
+
+data = gs.parse_command("g.list", type=["rast", "vect"], format="json")


Suggested change

data = gs.parse_command("g.list", type=["rast", "vect"], format="json")

data = gs.parse_command("g.list", type=["raster", "vect"], format="json")

wenzeslaus

The messaging around -p needs to be little different here because the default format here is "shell" and there is a special flag for plain (while most of the other tools have default "plain" with -g for shell).

wenzeslaus · 2025-06-23T14:51:13Z

general/g.list/g.list.md

@@ -27,7 +33,7 @@ g.list type=vector -m
 List all raster and vector maps ordered by mapset:

 ```sh
-g.list type=raster -p
+g.list type=raster format=plain


-p is for interactive use, so typing format=plain does not make much sense. While not ideal, in this case, -p needs to stay as is for now, so here:

Suggested change

g.list type=raster format=plain

g.list type=raster,vector -p

(I'm also fixing the type to align with the description above that.)

wenzeslaus · 2025-06-23T14:51:57Z

general/g.list/g.list.md

@@ -27,7 +33,7 @@ g.list type=vector -m
 List all raster and vector maps ordered by mapset:


Suggested change

List all raster and vector maps ordered by mapset:

List all raster and vector maps grouped by mapset in plain format:

wenzeslaus · 2025-06-23T14:55:17Z

general/g.list/g.list.md

+The flags `-p` and `-f` apply only to plain format output, but they are now
+deprecated and will be removed in a future release. Instead of using those, use
+`format=plain` to obtain human-readable plain text output.


Suggested change

The flags `-p` and `-f` apply only to plain format output, but they are now

deprecated and will be removed in a future release. Instead of using those, use

`format=plain` to obtain human-readable plain text output.

The flags `-p` and `-f` apply only to plain format output, but they are now

deprecated and will be removed in a future release. Instead of using those, use

`format="plain"` to obtain human-readable, plain text output. The plain format will

become the default in a future release.

To obtain machine readable output use `format="shell"` or `format="json"`.

wenzeslaus · 2025-06-23T14:56:46Z

general/g.list/g.list.md

+```python
+import grass.script as gs
+
+data = gs.parse_command("g.list", type=["rast", "vect"], format="json")


While the shorter versions work, the full versions are the best practice for a Python script.

Suggested change

data = gs.parse_command("g.list", type=["rast", "vect"], format="json")

data = gs.parse_command("g.list", type=["raster", "vector"], format="json")

wenzeslaus · 2025-06-23T14:57:33Z

general/g.list/g.list.md

 ### Mapset search path

 If **mapset** is not specified, then *g.list* searches for data files in
 the mapsets that are included in the search path (defined by
 *[g.mapsets](g.mapsets.md)*). See `g.mapsets -p`.

 ```sh
-g.list rast -p
+g.list rast format=plain


Suggested change

g.list rast format=plain

g.list rast -p

wenzeslaus · 2025-06-23T14:57:42Z

general/g.list/g.list.md

@@ -72,7 +93,7 @@ available mapsets also including those that are not listed in the
 current search path (see `g.mapsets -l`).

 ```sh
-g.list rast mapset=* -p
+g.list rast mapset=* format=plain


Suggested change

g.list rast mapset=* format=plain

g.list rast mapset=* -p

wenzeslaus · 2025-06-23T15:02:42Z

general/g.list/main.c

+        "This flag is deprecated and will be removed in a future release. Use "
+        "format=plain instead.");


This better describes the situation. Let me know if it makes sense:

Suggested change

"This flag is deprecated and will be removed in a future release. Use "

"format=plain instead.");

"This flag is deprecated and will be removed in a future release. The "

"plain format will become the default. Use format=\"plain\" to set it "

"explicitly in a script.");

wenzeslaus · 2025-06-23T15:06:50Z

general/g.list/main.c

-    flag.full->description = _("Verbose listing (also list map titles)");
+    flag.full->label = _("Verbose listing (also list map titles) [deprecated]");
+    flag.full->description =
+        _("This flag is deprecated and will be removed in a future release.");


It is little nicer to tell user what to do instead:

Suggested change

_("This flag is deprecated and will be removed in a future release.");

_("This flag is deprecated and will be removed in a future release. "

" Use the type-specific tool to obtain metadata, such as r.info "

"and v.info.");

wenzeslaus · 2025-06-23T15:19:30Z

general/g.list/main.c

+            G_verbose_message(
+                _("Flag 'p' is deprecated and will be removed in a future "
+                  "release. Please use format=plain instead."));


Suggested change

G_verbose_message(

_("Flag 'p' is deprecated and will be removed in a future "

"release. Please use format=plain instead."));

// Do not switch this to a warning until v9. The depreciation is

// documented, but warning would be too distracting given the

// likely interactive use of this flag. In v9.0, either remove it

// or make this into a warning and remove it in v9.1.

G_verbose_message(

_("Flag 'p' is deprecated and will be removed in a future "

"release where plain will be the default format. Use "

"format=\"plain\" to set plain format for scripting."));

Signed-off-by: Nishant Bansal <[email protected]>

g.list: add json support

b68c92d

Signed-off-by: Nishant Bansal <[email protected]>

github-actions bot added Python Related code is in Python C Related code is in C module docs markdown Related to markdown, markdown files general tests Related to Test Suite CMake labels Jun 20, 2025

cwhite911 added this to GRASS JSON Outputs Jun 20, 2025

cwhite911 moved this to In Progress in GRASS JSON Outputs Jun 20, 2025

petrasovaa reviewed Jun 23, 2025

View reviewed changes

wenzeslaus requested changes Jun 23, 2025

View reviewed changes

address review comments

917b6b7

Signed-off-by: Nishant Bansal <[email protected]>

NishantBansal2003 requested review from petrasovaa and wenzeslaus June 24, 2025 05:24

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g.list: Add JSON support #5921

g.list: Add JSON support #5921

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	data = gs.parse_command("g.list", type=["rast", "vect"], format="json")
	data = gs.parse_command("g.list", type=["raster", "vect"], format="json")

		@@ -27,7 +33,7 @@ g.list type=vector -m
		List all raster and vector maps ordered by mapset:

	List all raster and vector maps ordered by mapset:
	List all raster and vector maps grouped by mapset in plain format:

		"This flag is deprecated and will be removed in a future release. Use "
		"format=plain instead.");

-        "This flag is deprecated and will be removed in a future release. Use "
-        "format=plain instead.");
+        "This flag is deprecated and will be removed in a future release. The "
+        "plain format will become the default. Use format=\"plain\" to set it "
+        "explicitly in a script.");

-        _("This flag is deprecated and will be removed in a future release.");
+        _("This flag is deprecated and will be removed in a future release. "
+          " Use the type-specific tool to obtain metadata, such as r.info "
+          "and v.info.");

-            G_verbose_message(
-                _("Flag 'p' is deprecated and will be removed in a future "
-                  "release. Please use format=plain instead."));
+            // Do not switch this to a warning until v9. The depreciation is
+            // documented, but warning would be too distracting given the
+            // likely interactive use of this flag. In v9.0, either remove it
+            // or make this into a warning and remove it in v9.1.
+            G_verbose_message(
+                _("Flag 'p' is deprecated and will be removed in a future "
+                  "release where plain will be the default format. Use "
+                  "format=\"plain\" to set plain format for scripting."));

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NishantBansal2003 commented Jun 20, 2025

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