Add serializer for the progress models.

closes #2302
https://pulp.plan.io/issues/2302

app/pulp/app/models/__init__.py

@@ -13,4 +13,4 @@
 from .task import ReservedResource, Worker, Task, TaskTag, TaskLock  # NOQA
 
 # Moved here to avoid a circular import with Task
-from .progress import ProgressBar, ProgressSpinner  # NOQA
+from .progress import ProgressBar, ProgressReport, ProgressSpinner  # NOQA

app/pulp/app/serializers/__init__.py

@@ -9,6 +9,7 @@
     NotesKeyValueRelatedField, ScratchpadKeyValueRelatedField)  # NOQA
 from pulp.app.serializers.consumer import ConsumerSerializer  # NOQA
 from pulp.app.serializers.content import ContentSerializer, ArtifactSerializer  # NOQA
+from pulp.app.serializers.progress import ProgressReportSerializer  # NOQA
 from pulp.app.serializers.repository import (ImporterSerializer, PublisherSerializer,  # NOQA
     RepositoryGroupSerializer, RepositorySerializer)  # NOQA
 from pulp.app.serializers.task import TaskSerializer, WorkerSerializer  # NOQA

app/pulp/app/serializers/progress.py

@@ -0,0 +1,44 @@
+from gettext import gettext as _
+
+from rest_framework import serializers
+
+from pulp.app import models
+from pulp.app.serializers import ModelSerializer
+
+
+class ProgressReportSerializer(ModelSerializer):
+
+    message = serializers.CharField(
+        help_text=_("The message shown to the user for the progress report."),
+        read_only=True
+    )
+
+    state = serializers.CharField(
+        help_text=_("The current state of the progress report. The possible values are:"
+                    " 'waiting', 'skipped', 'running', 'completed', 'failed' and 'canceled'."
+                    " The default is 'waiting'."),
+        read_only=True
+    )
+
+    total = serializers.IntegerField(
+        help_text=_("The total count of items to be handled by the ProgressBar."),
+        read_only=True
+    )
+
+    done = serializers.IntegerField(
+        help_text=_("The count of items already processed. Defaults to 0."),
+        read_only=True
+    )
+
+    task = serializers.HyperlinkedRelatedField(
+        help_text=_("The task associated with this progress report."),
+        read_only=True,
+        view_name='tasks-detail'
+    )
+
+    class Meta:
+        model = models.ProgressReport
+        # this serializer is meant to be nested inside Task serializer,
+        # so it will not have its own endpoint, that's why
+        # we need to explicitly define fields to exclude '_href' field.
+        fields = ('message', 'state', 'total', 'done', 'task')