searcher: Allow the search to be sorted by an unsigned field.

src/index.rs

@@ -8,7 +8,7 @@ use crate::document::{extract_value, Document};
 use crate::query::Query;
 use crate::schema::Schema;
 use crate::searcher::Searcher;
-use crate::to_pyerr;
+use crate::{to_pyerr, get_field};
 use tantivy as tv;
 use tantivy::directory::MmapDirectory;
 use tantivy::schema::{Field, NamedFieldDocument, Term, Value};
@@ -111,13 +111,7 @@ impl IndexWriter {
         field_name: &str,
         field_value: &PyAny,
     ) -> PyResult<u64> {
-        let field = self.schema.get_field(field_name).ok_or_else(|| {
-            exceptions::ValueError::py_err(format!(
-                "Field `{}` is not defined in the schema.",
-                field_name
-            ))
-        })?;
-
+        let field = get_field(&self.schema, field_name)?;
         let value = extract_value(field_value)?;
         let term = match value {
             Value::Str(text) => Term::from_field_text(field, &text),
@@ -274,6 +268,7 @@ impl Index {
     fn searcher(&self) -> Searcher {
         Searcher {
             inner: self.reader.searcher(),
+            schema: self.index.schema(),
         }
     }
 

src/lib.rs

@@ -1,5 +1,6 @@
 use pyo3::exceptions;
 use pyo3::prelude::*;
+use tantivy as tv;
 
 mod document;
 mod facet;
@@ -83,3 +84,14 @@ fn tantivy(_py: Python, m: &PyModule) -> PyResult<()> {
 pub(crate) fn to_pyerr<E: ToString>(err: E) -> PyErr {
     exceptions::ValueError::py_err(err.to_string())
 }
+
+pub(crate) fn get_field(schema: &tv::schema::Schema, field_name: &str) -> PyResult<tv::schema::Field> {
+    let field = schema.get_field(field_name).ok_or_else(|| {
+        exceptions::ValueError::py_err(format!(
+            "Field `{}` is not defined in the schema.",
+                field_name
+        ))
+    })?;
+
+    Ok(field)
+}

src/searcher.rs

@@ -2,9 +2,9 @@
 
 use crate::document::Document;
 use crate::query::Query;
-use crate::to_pyerr;
+use crate::{to_pyerr, get_field};
 use pyo3::prelude::*;
-use pyo3::{exceptions, PyObjectProtocol};
+use pyo3::PyObjectProtocol;
 use tantivy as tv;
 
 /// Tantivy's Searcher class
@@ -13,8 +13,11 @@ use tantivy as tv;
 #[pyclass]
 pub(crate) struct Searcher {
     pub(crate) inner: tv::LeasedItem<tv::Searcher>,
+    pub(crate) schema: tv::schema::Schema,
 }
 
+const SORT_BY: &str = "";
+
 #[pymethods]
 impl Searcher {
     /// Search the index with the given query and collect results.
@@ -29,26 +32,31 @@ impl Searcher {
     /// search results.
     ///
     /// Raises a ValueError if there was an error with the search.
-    #[args(limit = 10)]
+    #[args(limit = 10, sort_by = "SORT_BY")]
     fn search(
         &self,
         py: Python,
         query: &Query,
         limit: usize,
+        sort_by: &str,
     ) -> PyResult<Vec<(PyObject, DocAddress)>> {
+        let field = match sort_by {
+            "" => None,
+            field_name => Some(get_field(&self.schema, field_name)?)
+        };
+
+        let result = if let Some(f) = field {
+            let collector = tv::collector::TopDocs::with_limit(limit).order_by_u64_field(f);
+            let ret = self.inner.search(&query.inner, &collector).map_err(to_pyerr)?;
+            ret.iter().map(|(f, d)| ((*f).into_py(py), DocAddress::from(d))).collect()
+        } else {
             let collector = tv::collector::TopDocs::with_limit(limit);
-        let ret = self.inner.search(&query.inner, &collector);
+            let ret = self.inner.search(&query.inner, &collector).map_err(to_pyerr)?;
+            ret.iter().map(|(f, d)| ((*f).into_py(py), DocAddress::from(d))).collect()
+        };
 
-        match ret {
-            Ok(r) => {
-                let result: Vec<(PyObject, DocAddress)> =
-                    r.iter().map(|(f, d)| ((*f).into_py(py), DocAddress::from(d))).collect();
         Ok(result)
     }
-            Err(e) => Err(exceptions::ValueError::py_err(e.to_string())),
-        }
-
-    }
 
     /// Returns the overall number of documents in the index.
     #[getter]

tests/tantivy_test.py

@@ -131,6 +131,34 @@ class TestClass(object):
         with pytest.raises(ValueError):
             index.parse_query("bod:men", ["title", "body"])
 
+    def test_sort_by_search(self):
+        schema = (
+            SchemaBuilder()
+            .add_text_field("message", stored=True)
+            .add_unsigned_field("timestamp", stored=True, fast="single")
+            .build()
+        )
+        index = Index(schema)
+        writer = index.writer()
+        doc = Document()
+        doc.add_text("message", "Test message")
+        doc.add_unsigned("timestamp", 1569954264)
+        writer.add_document(doc)
+
+        doc = Document()
+        doc.add_text("message", "Another test message")
+        doc.add_unsigned("timestamp", 1569954280)
+
+        writer.add_document(doc)
+
+        writer.commit()
+        index.reload()
+
+        query = index.parse_query("test")
+        result = index.searcher().search(query, 10, sort_by="timestamp")
+        assert result[0][0] == 1569954280
+        assert result[1][0] == 1569954264
+
 
 class TestUpdateClass(object):
     def test_delete_update(self, ram_index):