From 3220598e39dc5d4019daa7d36aa0aef2ce62e44e Mon Sep 17 00:00:00 2001
From: Nate Potter <nathaniel.potter@intel.com>
Date: Fri, 18 Aug 2017 16:10:17 -0700
Subject: [PATCH] Add ListField class to resource base

Add a class capable of handling lists of fields in resource
body JSON. This is a general purpose class, and is being added
for use in the rsd-lib sushy extension as there are JSON responses
such as {"Initiator": [{"iSCSI": 1}, {"iSCSI": 2}]} that need to
be handled.

Change-Id: I6053967177ddb045a79f373e1cf22529d6d71a5c
---
 sushy/resources/base.py                 | 34 +++++++++++++++++++++++++
 sushy/tests/unit/resources/test_base.py | 21 ++++++++++++++-
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/sushy/resources/base.py b/sushy/resources/base.py
index a6083ba4..31d06e68 100644
--- a/sushy/resources/base.py
+++ b/sushy/resources/base.py
@@ -153,6 +153,40 @@ class CompositeField(collections.Mapping, Field):
         return iter(self._subfields)
 
 
+class ListField(Field):
+    """Base class for fields consisting of a list of several sub-fields."""
+
+    def __init__(self, *args, **kwargs):
+        super(ListField, self).__init__(*args, **kwargs)
+        self._subfields = dict(_collect_fields(self))
+
+    def _load(self, body, resource, nested_in=None):
+        """Load the field list.
+
+        :param body: parent JSON body.
+        :param resource: parent resource.
+        :param nested_in: parent resource name (for error reporting only).
+        :returns: a new list object containing subfields.
+        """
+        nested_in = (nested_in or []) + self._path
+        values = super(ListField, self)._load(body, resource)
+        if values is None:
+            return None
+
+        # Initialize the list that will contain each field instance
+        instances = []
+        for value in values:
+            instance = copy.copy(self)
+            for attr, field in self._subfields.items():
+                # Hide the Field object behind the real value
+                setattr(instance, attr, field._load(value,
+                                                    resource,
+                                                    nested_in))
+            instances.append(instance)
+
+        return instances
+
+
 class MappedField(Field):
     """Field taking real value from a mapping."""
 
diff --git a/sushy/tests/unit/resources/test_base.py b/sushy/tests/unit/resources/test_base.py
index 96a1db44..ad7e0ed6 100644
--- a/sushy/tests/unit/resources/test_base.py
+++ b/sushy/tests/unit/resources/test_base.py
@@ -138,7 +138,17 @@ TEST_JSON = {
             'Field': 'field value'
         },
         'Mapped': 'raw'
-    }
+    },
+    'ListField': [
+        {
+            'String': 'a third string',
+            'Integer': 1
+        },
+        {
+            'String': 'a fourth string',
+            'Integer': 2
+        }
+    ]
 }
 
 
@@ -155,10 +165,16 @@ class NestedTestField(resource_base.CompositeField):
     non_existing = resource_base.Field('NonExisting', default=3.14)
 
 
+class TestListField(resource_base.ListField):
+    string = resource_base.Field('String', required=True)
+    integer = resource_base.Field('Integer', adapter=int)
+
+
 class ComplexResource(resource_base.ResourceBase):
     string = resource_base.Field('String', required=True)
     integer = resource_base.Field('Integer', adapter=int)
     nested = NestedTestField('Nested')
+    field_list = TestListField('ListField')
     non_existing_nested = NestedTestField('NonExistingNested')
     non_existing_mapped = resource_base.MappedField('NonExistingMapped',
                                                     MAPPING)
@@ -181,6 +197,9 @@ class FieldTestCase(base.TestCase):
         self.assertEqual('field value', self.test_resource.nested.nested_field)
         self.assertEqual('real', self.test_resource.nested.mapped)
         self.assertEqual(3.14, self.test_resource.nested.non_existing)
+        self.assertEqual('a third string',
+                         self.test_resource.field_list[0].string)
+        self.assertEqual(2, self.test_resource.field_list[1].integer)
         self.assertIsNone(self.test_resource.non_existing_nested)
         self.assertIsNone(self.test_resource.non_existing_mapped)