Add struct2dbtable function and use it in sqlite functions

INDEX

@@ -14,3 +14,4 @@ Database Operations
   @octave_sqlite/rollback
 Support Functions
   dbtable
+  struct2dbtable

inst/@octave_sqlite/fetch.m

@@ -79,7 +79,7 @@
   endfor
 
   data = __sqlite_fetch__(db, query);
-  data = dbtable(data);
+  data = struct2dbtable(data);
 endfunction
 
 %!test

inst/@octave_sqlite/sqlwrite.m

@@ -67,10 +67,10 @@ function sqlwrite (db, tablename, data, varargin)
   endif
 
   if isa(data, "struct")
-    data = dbtable(data);
+    data = struct2dbtable(data);
   endif
-  if !isa(data, "dbtable")
-    error ("Expected input data as a dbtable or struct");
+  if !isa(data, "dbtable") && !isa(data, "table")
+    error ("Expected input data as a table or struct");
   endif
 
   # for some reason, the subref using '.' on data isnt working here

inst/struct2dbtable.m

@@ -0,0 +1,51 @@
+## Copyright (C) 2022 John Donoghue <john.donoghue@ieee.org>
+##
+## This program is free software: you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program.  If not, see
+## <https://www.gnu.org/licenses/>.
+
+## -*- texinfo -*- 
+## @deftypefn {} {@var{t} =} struct2dbtable (@var{astruct})
+## Create a table from a struct
+## 
+## If a table function exists, use it to create the table, otherwise, use the 
+## dbtable type to create it.
+##
+## @subsubheading Inputs:
+## @table @asis
+## @item @var{astruct} 
+## A struct with same number of elements in each field
+## @endtable
+##
+## @subsubheading Outputs:
+## @table @asis
+## @item @var{t} 
+## a table (if table exists) or dbtable of the astruct data
+## @endtable
+##
+## @end deftypefn
+
+function t = struct2dbtable (astruct)
+  if ! isstruct(astruct)
+    error ("Not a struct");
+  endif
+
+  names = fieldnames(astruct);
+  values = struct2cell(astruct);
+
+  if exist("table") == 2
+    t = table (values{:}, 'VariableNames', names);
+  else
+    t = dbtable (values{:}, 'VariableNames', names');
+  endif
+endfunction