Add records.get RPC function

db/records/operations/select.py

@@ -50,6 +50,29 @@ def list_records_from_table(
     return result
 
 
+def get_record_from_table(
+        conn,
+        record_id,
+        table_oid,
+):
+    """
+    Get single record from a table by its primary key
+
+    Only data from which the user is granted `SELECT` is returned.
+
+    Args:
+        record_id: The primary key value of the record.
+        table_id: The OID of the table whose record we'll get.
+    """
+    result = db_conn.exec_msar_func(
+        conn,
+        'get_record_from_table',
+        table_oid,
+        record_id,
+    ).fetchone()[0]
+    return result
+
+
 def search_records_from_table(
         conn,
         table_oid,

db/sql/00_msar.sql

@@ -571,7 +571,7 @@ Return the first column attnum in the primary key of a given relation (e.g., tab
 Args:
   rel_id: The OID of the relation.
 */
-SELECT conkey[1]
+SELECT CASE WHEN array_length(conkey, 1) = 1 THEN conkey[1] END
 FROM pg_constraint
 WHERE contype='p'
 AND conrelid=rel_id;
@@ -586,7 +586,7 @@ Args:
   sch_name: The schema of the relation, unquoted.
   rel_name: The name of the relation, unqualified and unquoted.
 */
-SELECT conkey[1]
+SELECT CASE WHEN array_length(conkey, 1) = 1 THEN conkey[1] END
 FROM pg_constraint
 WHERE contype='p'
 AND conrelid=msar.get_relation_oid(sch_name, rel_name);
@@ -3714,3 +3714,26 @@ BEGIN
   RETURN records;
 END;
 $$ LANGUAGE plpgsql;
+
+
+CREATE OR REPLACE FUNCTION
+msar.get_record_from_table(tab_id oid, rec_id anyelement) RETURNS jsonb AS $$/*
+Get single record from a table. Only columns to which the user has access are returned.
+
+Args:
+  tab_id: The OID of the table whose record we'll get.
+  rec_id: The id value of the record.
+
+The table must have a single primary key column.
+*/
+SELECT msar.list_records_from_table(
+  tab_id, null, null, null,
+  jsonb_build_object(
+    'type', 'equal', 'args', jsonb_build_array(
+      jsonb_build_object('type', 'attnum', 'value', msar.get_pk_column(tab_id)),
+      jsonb_build_object('type', 'literal', 'value', rec_id)
+    )
+  ),
+  null
+)
+$$ LANGUAGE SQL STABLE RETURNS NULL ON NULL INPUT;

db/sql/test_00_msar.sql

@@ -3696,3 +3696,45 @@ BEGIN
   RETURN NEXT is((search_result -> 'count')::integer, 3);
 END;
 $$ LANGUAGE plpgsql;
+
+
+CREATE OR REPLACE FUNCTION test_get_record_from_table() RETURNS SETOF TEXT AS $$
+DECLARE
+  rel_id oid;
+BEGIN
+  PERFORM __setup_list_records_table();
+  rel_id := 'atable'::regclass::oid;
+  RETURN NEXT is(
+    msar.get_record_from_table(rel_id, 2),
+    $j${
+      "count": 1,
+      "results": [
+        {"1": 2, "2": 34, "3": "sdflfflsk", "4": null, "5": [1, 2, 3, 4]}
+      ],
+      "grouping": null
+    }$j$ || jsonb_build_object(
+      'query', concat(
+        'SELECT msar.format_data(id) AS "1", msar.format_data(col1) AS "2",',
+        ' msar.format_data(col2) AS "3", msar.format_data(col3) AS "4",',
+        ' msar.format_data(col4) AS "5" FROM public.atable WHERE (id) = (''2'')',
+        ' ORDER BY "1" ASC LIMIT NULL OFFSET NULL'
+      )
+    )
+  );
+  RETURN NEXT is(
+    msar.get_record_from_table(rel_id, 200),
+    $j${
+      "count": 0,
+      "results": [],
+      "grouping": null
+    }$j$ || jsonb_build_object(
+      'query', concat(
+        'SELECT msar.format_data(id) AS "1", msar.format_data(col1) AS "2",',
+        ' msar.format_data(col2) AS "3", msar.format_data(col3) AS "4",',
+        ' msar.format_data(col4) AS "5" FROM public.atable WHERE (id) = (''200'')',
+        ' ORDER BY "1" ASC LIMIT NULL OFFSET NULL'
+      )
+    )
+  );
+END;
+$$ LANGUAGE plpgsql;

docs/docs/api/rpc.md

@@ -182,6 +182,7 @@ To use an RPC function:
     options:
       members:
       - list_
+      - get
       - search
       - RecordList
       - OrderBy

mathesar/rpc/records.py

@@ -189,6 +189,37 @@ def list_(
     return RecordList.from_dict(record_info)
 
 
+@rpc_method(name="records.get")
+@http_basic_auth_login_required
+@handle_rpc_exceptions
+def get(
+        *,
+        record_id: Any,
+        table_oid: int,
+        database_id: int,
+        **kwargs
+) -> RecordList:
+    """
+    Get single record from a table by its primary key.
+
+    Args:
+        record_id: The primary key value of the record to be gotten.
+        table_oid: Identity of the table in the user's database.
+        database_id: The Django id of the database containing the table.
+
+    Returns:
+        The requested record, along with some metadata.
+    """
+    user = kwargs.get(REQUEST_KEY).user
+    with connect(database_id, user) as conn:
+        record_info = record_select.get_record_from_table(
+            conn,
+            record_id,
+            table_oid,
+        )
+    return RecordList.from_dict(record_info)
+
+
 @rpc_method(name="records.search")
 @http_basic_auth_login_required
 @handle_rpc_exceptions

mathesar/tests/rpc/test_endpoints.py

@@ -149,6 +149,11 @@
         "records.list",
         [user_is_authenticated]
     ),
+    (
+        records.get,
+        "records.get",
+        [user_is_authenticated]
+    ),
     (
         records.search,
         "records.search",

mathesar/tests/rpc/test_records.py

@@ -72,6 +72,54 @@ def mock_list_records(
     assert actual_records_list == expect_records_list
 
 
+def test_records_get(rf, monkeypatch):
+    username = 'alice'
+    password = 'pass1234'
+    table_oid = 23457
+    database_id = 2
+    record_id = 2342
+    request = rf.post('/api/rpc/v0/', data={})
+    request.user = User(username=username, password=password)
+
+    @contextmanager
+    def mock_connect(_database_id, user):
+        if _database_id == database_id and user.username == username:
+            try:
+                yield True
+            finally:
+                pass
+        else:
+            raise AssertionError('incorrect parameters passed')
+
+    def mock_get_record(
+            conn,
+            _record_id,
+            _table_oid,
+    ):
+        if _table_oid != table_oid or _record_id != record_id:
+            raise AssertionError('incorrect parameters passed')
+        return {
+            "count": 1,
+            "results": [{"1": "abcde", "2": 12345}, {"1": "fghij", "2": 67890}],
+            "query": 'SELECT mycol AS "1", anothercol AS "2" FROM mytable LIMIT 2',
+            "grouping": None,
+        }
+
+    monkeypatch.setattr(records, 'connect', mock_connect)
+    monkeypatch.setattr(records.record_select, 'get_record_from_table', mock_get_record)
+    expect_record = {
+        "count": 1,
+        "results": [{"1": "abcde", "2": 12345}, {"1": "fghij", "2": 67890}],
+        "grouping": None,
+        "preview_data": [],
+        "query": 'SELECT mycol AS "1", anothercol AS "2" FROM mytable LIMIT 2',
+    }
+    actual_record = records.get(
+        record_id=record_id, table_oid=table_oid, database_id=database_id, request=request
+    )
+    assert actual_record == expect_record
+
+
 def test_records_search(rf, monkeypatch):
     username = 'alice'
     password = 'pass1234'