Wrap Searcher.doc_freq. Fixes #344 (#345)

src/searcher.rs

@@ -276,6 +276,20 @@ impl Searcher {
         self.inner.segment_readers().len()
     }
 
+    /// Return the overall number of documents containing
+    /// the given term.
+    #[pyo3(signature = (field_name, field_value))]
+    fn doc_freq(
+        &self,
+        field_name: &str,
+        field_value: &Bound<PyAny>,
+    ) -> PyResult<u64> {
+        // Wrap the tantivy Searcher `doc_freq` method to return a PyResult.
+        let schema = self.inner.schema();
+        let term = crate::make_term(schema, field_name, field_value)?;
+        self.inner.doc_freq(&term).map_err(to_pyerr)
+    }
+
     /// Fetches a document from Tantivy's store given a DocAddress.
     ///
     /// Args:

tantivy/tantivy.pyi

@@ -337,6 +337,9 @@ class Searcher:
     def doc(self, doc_address: DocAddress) -> Document:
         pass
 
+    def doc_freq(self, field_name: str, field_value: Any) -> int:
+        pass
+
 class IndexWriter:
     def add_document(self, doc: Document) -> int:
         pass

tests/tantivy_test.py

@@ -64,6 +64,12 @@ class TestClass(object):
 
         assert len(result.hits) == 1
 
+    def test_doc_freq(self, ram_index):
+        index = ram_index
+        searcher = index.searcher()
+        doc_freq = searcher.doc_freq("body", "and")
+        assert doc_freq == 3
+
     def test_and_aggregate(self, ram_index_numeric_fields):
         index = ram_index_numeric_fields
         query = Query.all_query()