cli: Have way to delete payload field in `rad id`

Allow for deleting a field by setting it to `null`.

rad-id.1.adoc

@@ -76,7 +76,7 @@ automatically accepted and included into the identity document.
 *--payload* _<id> <key> <val>_::
   Update the identity by setting metadata in one of the identity payloads.
   This can be used to update a repository's project name or description, for
-  example.
+  example. To delete a field from a payload, simply set it to *null*.
 
 *--no-confirm*::
   Don't ask for confirmation before creating the revision.

radicle-cli/examples/rad-id-update-delete-field.md

@@ -0,0 +1,71 @@
+Let's add a payload field and then delete it.
+
+```
+$ rad id update --title "Add field" --description "Add a new 'web' field" --payload xyz.radicle.project web '"https://acme.example"'
+✓ Identity revision a8a9fee6c4f83578ab132d375f1da0c81282bef3 created
+╭───────────────────────────────────────────────────────────────────╮
+│ Title    Add field                                                │
+│ Revision a8a9fee6c4f83578ab132d375f1da0c81282bef3                 │
+│ Blob     fbe268d13e60f1f3a1972e0ccd592f3cdecf08b5                 │
+│ Author   did:key:z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi │
+│ State    accepted                                                 │
+│ Quorum   yes                                                      │
+│                                                                   │
+│ Add a new 'web' field                                             │
+├───────────────────────────────────────────────────────────────────┤
+│ ✓ did:key:z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi  (you) │
+╰───────────────────────────────────────────────────────────────────╯
+
+@@ -1,13 +1,14 @@
+ {
+   "payload": {
+     "xyz.radicle.project": {
+       "defaultBranch": "master",
+       "description": "Radicle Heartwood Protocol & Stack",
+-      "name": "heartwood"
++      "name": "heartwood",
++      "web": "https://acme.example"
+     }
+   },
+   "delegates": [
+     "did:key:z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi"
+   ],
+   "threshold": 1
+ }
+```
+
+Now let's delete it by setting it to `null`.
+
+```
+$ rad id update --title "Delete field" --description "Delete 'web'" --payload xyz.radicle.project web null
+✓ Identity revision d373c35876833105f8aafed8b610660b5737cd67 created
+╭───────────────────────────────────────────────────────────────────╮
+│ Title    Delete field                                             │
+│ Revision d373c35876833105f8aafed8b610660b5737cd67                 │
+│ Blob     d96f425412c9f8ad5d9a9a05c9831d0728e2338d                 │
+│ Author   did:key:z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi │
+│ State    accepted                                                 │
+│ Quorum   yes                                                      │
+│                                                                   │
+│ Delete 'web'                                                      │
+├───────────────────────────────────────────────────────────────────┤
+│ ✓ did:key:z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi  (you) │
+╰───────────────────────────────────────────────────────────────────╯
+
+@@ -1,14 +1,13 @@
+ {
+   "payload": {
+     "xyz.radicle.project": {
+       "defaultBranch": "master",
+       "description": "Radicle Heartwood Protocol & Stack",
+-      "name": "heartwood",
+-      "web": "https://acme.example"
++      "name": "heartwood"
+     }
+   },
+   "delegates": [
+     "did:key:z6MknSLrJoTcukLrE435hVNQT4JUhbvWLX4kUzqkEStBU8Vi"
+   ],
+   "threshold": 1
+ }
+```

radicle-cli/src/commands/id.rs

@@ -378,7 +378,11 @@ pub fn run(options: Options, ctx: impl term::Context) -> anyhow::Result<()> {
                 for (id, key, val) in payload {
                     if let Some(ref mut payload) = proposal.payload.get_mut(&id) {
                         if let Some(obj) = payload.as_object_mut() {
-                            obj.insert(key, val);
+                            if val.is_null() {
+                                obj.remove(&key);
+                            } else {
+                                obj.insert(key, val);
+                            }
                         } else {
                             anyhow::bail!("payload `{id}` is not a map");
                         }

radicle-cli/tests/commands.rs

@@ -418,6 +418,33 @@ fn rad_id_threshold() {
         .unwrap();
 }
 
+#[test]
+fn rad_id_update_delete_field() {
+    let mut environment = Environment::new();
+    let alice = environment.node(config::node("alice"));
+    let working = tempfile::tempdir().unwrap();
+    let working = working.path();
+
+    // Setup a test repository.
+    fixtures::repository(working.join("alice"));
+
+    test(
+        "examples/rad-init.md",
+        working.join("alice"),
+        Some(&alice.home),
+        [],
+    )
+    .unwrap();
+
+    test(
+        "examples/rad-id-update-delete-field.md",
+        working.join("alice"),
+        Some(&alice.home),
+        [],
+    )
+    .unwrap();
+}
+
 #[test]
 fn rad_id_multi_delegate() {
     let mut environment = Environment::new();