From 629d9244b9b5eaefe0e78a43c53335f07dcdce6d Mon Sep 17 00:00:00 2001
From: Robert Forkel <xrotwang@googlemail.com>
Date: Fri, 26 Apr 2024 17:05:28 +0200
Subject: [PATCH] closes #173

---
 CHANGELOG.md             |  1 +
 src/pycldf/validators.py | 11 +++++++++++
 tests/test_dataset.py    | 11 +++++++++++
 3 files changed, 23 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index bb198ea..2febd70 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ The `pycldf` package adheres to [Semantic Versioning](http://semver.org/spec/v2.
   by `json.dumps`.
 - Fixed bug whereby SQLite conversion would fail when the name of a renamed column clashed with an
   existing column name in the table.
+- Emit warning when encountering invalid main part for mediaType property.
 
 
 ## [1.37.1] - 2024-03-18
diff --git a/src/pycldf/validators.py b/src/pycldf/validators.py
index 80cffd8..d252d54 100644
--- a/src/pycldf/validators.py
+++ b/src/pycldf/validators.py
@@ -1,4 +1,5 @@
 import re
+import warnings
 import functools
 
 
@@ -37,6 +38,12 @@ def valid_grammaticalityJudgement(dataset, table, column, row):
             raise ValueError('Glottolog language linked from ungrammatical example')
 
 
+def valid_mediaType(dataset, table, column, row):
+    main, _, sub = row[column.name].partition('/')
+    if not re.fullmatch('[a-z]+', main):
+        warnings.warn('Invalid main part in media type: {}'.format(main))
+
+
 VALIDATORS = [
     (
         None,
@@ -58,4 +65,8 @@ def valid_grammaticalityJudgement(dataset, table, column, row):
         None,
         'http://cldf.clld.org/v1.0/terms.rdf#grammaticalityJudgement',
         valid_grammaticalityJudgement),
+    (
+        None,
+        'http://cldf.clld.org/v1.0/terms.rdf#mediaType',
+        valid_mediaType),
 ]
diff --git a/tests/test_dataset.py b/tests/test_dataset.py
index 086c775..4f6d9db 100644
--- a/tests/test_dataset.py
+++ b/tests/test_dataset.py
@@ -2,6 +2,7 @@
 import logging
 import zipfile
 import warnings
+import mimetypes
 import contextlib
 
 import pytest
@@ -177,6 +178,16 @@ def test_example_validators(ds):
         ds.validate()
 
 
+def test_invalid_mimetype(ds, recwarn):
+    ds.add_component('MediaTable')
+    ds.write(MediaTable=[{
+        'ID': '1',
+        'Media_Type': mimetypes.guess_type('f.png'),
+        'Download_URL': 'http://example.org'}])
+    ds.validate()
+    assert 'Invalid main part' in str(recwarn.pop(UserWarning).message)
+
+
 def test_regex_validator_for_listvalued_column(ds):
     ds.add_table(
         'test',