Fix fields argument to CLI (#797)

* Split fields coming from CLI
* Add a test
* Update changelog

Author: jsignell

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Fixed
 
 - Fix usage documentation of `ItemSearch`
+- Fix fields argument to CLI  ([#797](https://github.com/stac-utils/pystac-client/pull/797))
 
 ## [v0.8.6] - 2025-02-11
 

pystac_client/item_search.py

@@ -159,7 +159,6 @@ def __init__(
 
         self.method = method
         self.modifier = modifier
-
         params = {
             "limit": limit,
             "bbox": self._format_bbox(bbox),
@@ -482,6 +481,8 @@ def _format_fields(self, value: FieldsLike | None) -> Fields | None:
         if isinstance(value, str):
             return self._fields_to_dict(value.split(","))
         if isinstance(value, list):
+            if len(value) == 1:
+                return self._fields_to_dict(value[0].split(","))
             return self._fields_to_dict(value)
         if isinstance(value, dict):
             return value