Add Equals operator.

Author: WaVEV

django_mongodb_backend/expressions/search.py

@@ -113,3 +113,46 @@ def search_operator(self, compiler, connection):
         if self.token_order is not None:
             params["tokenOrder"] = self.token_order.value
         return {"autocomplete": params}
+
+
+class SearchEquals(SearchExpression):
+    """
+    Atlas Search expression that matches documents with a field equal to the given value.
+
+    This expression uses the `equals` operator to perform exact matches
+    on fields indexed in a MongoDB Atlas Search index.
+
+    Example:
+        SearchEquals("category", "fiction")
+
+    Args:
+        path: The document path to compare (as string or expression).
+        value: The exact value to match against.
+        score: Optional expression to modify the relevance score.
+
+    Reference: https://www.mongodb.com/docs/atlas/atlas-search/equals/
+    """
+
+    def __init__(self, path, value, score=None):
+        self.path = cast_as_field(path)
+        self.value = cast_as_value(value)
+        self.score = score
+        super().__init__()
+
+    def get_search_fields(self, compiler, connection):
+        return {self.path.as_mql(compiler, connection, as_path=True)}
+
+    def get_source_expressions(self):
+        return [self.path, self.value]
+
+    def set_source_expressions(self, exprs):
+        self.path, self.value = exprs
+
+    def search_operator(self, compiler, connection):
+        params = {
+            "path": self.path.as_mql(compiler, connection, as_path=True),
+            "value": self.value.value,
+        }
+        if self.score is not None:
+            params["score"] = self.score.as_mql(compiler, connection)
+        return {"equals": params}