Add clone with headers_only option

Author: shahramn

CHANGELOG.rst

@@ -2,6 +2,11 @@
 Changelog for eccodes-python
 ============================
 
+1.7.0 (2024-MM-DD)
+--------------------
+
+- Add clone with headers only
+
 1.6.1 (2023-10-02)
 --------------------
 

gribapi/bindings.py

@@ -21,7 +21,7 @@
 
 import cffi
 
-__version__ = "1.6.1"
+__version__ = "1.7.0"
 
 LOG = logging.getLogger(__name__)
 

gribapi/grib_api.h

@@ -38,7 +38,7 @@ struct grib_values {
   int         has_value;
   int         equal;
   grib_values* next;
-} ;
+};
 
 typedef struct grib_handle    grib_handle;
 typedef struct grib_multi_handle    grib_multi_handle;
@@ -74,7 +74,8 @@ int grib_count_in_file(grib_context* c, FILE* f,int* n);
 grib_handle* grib_handle_new_from_file(grib_context* c, FILE* f, int* error);
 grib_handle* grib_handle_new_from_message_copy(grib_context* c, const void* data, size_t data_len);
 grib_handle* grib_handle_new_from_samples (grib_context* c, const char* sample_name);
-grib_handle* grib_handle_clone(const grib_handle* h)                 ;
+grib_handle* grib_handle_clone(const grib_handle* h);
+grib_handle* grib_handle_clone_headers_only(const grib_handle* h);
 int grib_handle_delete(grib_handle* h);
 grib_multi_handle* grib_multi_handle_new(grib_context* c);
 int grib_multi_handle_append(grib_handle* h,int start_section,grib_multi_handle* mh);
@@ -125,7 +126,7 @@ void grib_dump_content(const grib_handle* h, FILE* out, const char* mode, unsign
 grib_context* grib_context_get_default(void);
 void grib_context_delete(grib_context* c);
 
-void grib_gts_header_on(grib_context* c) ;
+void grib_gts_header_on(grib_context* c);
 void grib_gts_header_off(grib_context* c);
 void grib_gribex_mode_on(grib_context* c);
 void grib_gribex_mode_off(grib_context* c);

gribapi/gribapi.py

@@ -1121,7 +1121,7 @@ def codes_bufr_copy_data(msgid_src, msgid_dst):
 
 
 @require(msgid_src=int)
-def grib_clone(msgid_src):
+def grib_clone(msgid_src, headers_only=False):
     r"""
     @brief Create a copy of a message.
 
@@ -1130,12 +1130,16 @@ def grib_clone(msgid_src):
 
     \b Examples: \ref grib_clone.py "grib_clone.py"
 
-    @param msgid_src   id of message to be cloned
-    @return            id of clone
+    @param msgid_src    id of message to be cloned
+    @param headers_only whether or not to load the message with the headers only
+    @return             id of clone
     @exception CodesInternalError
     """
     h_src = get_handle(msgid_src)
-    h_dest = lib.grib_handle_clone(h_src)
+    if headers_only:
+        h_dest = lib.grib_handle_clone_headers_only(h_src)
+    else:
+        h_dest = lib.grib_handle_clone(h_src)
     if h_dest == ffi.NULL:
         raise errors.MessageInvalidError("clone failed")
     return put_handle(h_dest)

tests/test_eccodes.py

@@ -350,6 +350,18 @@ def test_grib_clone():
     eccodes.codes_release(clone)
 
 
+def test_grib_clone_headers_only():
+    with open(TEST_GRIB_ERA5_DATA, "rb") as f:
+        msgid1 = eccodes.codes_grib_new_from_file(f)
+        msgid2 = eccodes.codes_clone(msgid1, headers_only=True)
+        assert eccodes.codes_get(msgid1, "totalLength") == 14752
+        assert eccodes.codes_get(msgid2, "totalLength") == 112
+        assert eccodes.codes_get(msgid1, "bitsPerValue") == 16
+        assert eccodes.codes_get(msgid2, "bitsPerValue") == 0
+        eccodes.codes_release(msgid1)
+        eccodes.codes_release(msgid2)
+
+
 def test_grib_keys_iterator():
     gid = eccodes.codes_grib_new_from_samples("reduced_gg_pl_1280_grib1")
     iterid = eccodes.codes_keys_iterator_new(gid, "ls")