Fix: OperationFailure on Mongo full text searches

Closes #1176

CHANGES.rst

@@ -10,6 +10,7 @@ Unreleased
 
 Fixed
 ~~~~~
+- v0.8: ``OperationFailure`` performing MongoDB full text searches (`#1176`_)
 - ``AttributeError`` on Python 2.7 when obsolete ``JSON`` or ``XML`` settings are used (`#1175`_).
 - ``TypeError argument of type 'NoneType' is not iterable`` error when using document embedding in conjuction with soft deletes (`#1120`_)
 - ``allow_unknown`` validation rule fails with nested dict fields (`#1163`_)
@@ -40,6 +41,7 @@ Docs
 - Add a ``ISSUE_TEMPLATE.md`` GitHub template file. (`#1146`_)
 - Improve changelog format to reduce noise and increase readability. (`#1143`_)
 
+.. _`#1176`: https://github.com/pyeve/eve/issues/1176
 .. _`#1175`: https://github.com/pyeve/eve/issues/1175
 .. _`#1142`: https://github.com/pyeve/eve/issues/1142
 .. _`#1143`: https://github.com/pyeve/eve/issues/1143

eve/io/base.py

@@ -464,7 +464,7 @@ def _datasource_ex(
                 fields = client_projection
         # always drop exclusion projection, thus avoid mixed projection not
         # supported by db driver
-        fields = dict([(field, 1) for field, value in fields.items() if value])
+        fields = dict([(field, value) for field, value in fields.items() if value])
 
         # If the current HTTP method is in `public_methods` or
         # `public_item_methods`, skip the `auth_field` check