make gene length positive only

backend/metagenedb/api/catalog/views/gene.py

@@ -16,7 +16,7 @@ from metagenedb.apps.catalog.serializers import GeneSerializer
 window_size_param = openapi.Parameter('window_size', in_=openapi.IN_QUERY, description='Size of the window.',
                                       type=openapi.TYPE_INTEGER, default=10000)
 gene_length_schema = openapi.Schema("pouet", {}, type={'hihi': 'haha'})
-gene_length_response = openapi.Response('return JSON content', schema=gene_length_schema)
+gene_length_response = openapi.Response('Get the distribution of gene length for a given window size', schema=gene_length_schema)
 
 
 class GeneViewSet(mixins.ListModelMixin,
@@ -47,13 +47,12 @@ class GeneViewSet(mixins.ListModelMixin,
 
     @swagger_auto_schema(
         manual_parameters=[window_size_param],
-        responses = {
+        responses={
             '200': gene_length_response,
             '204': 'no content'
-        },        
+        },
         security=[],
         operation_id='List of categories',
-        operation_description='Get the distribution of gene length for a given window size.',
     )
     @action(methods=['get'], detail=False)
     def gene_length(self, request, window_size=10000):

backend/metagenedb/apps/catalog/migrations/0007_gene_length_positive.py

+# Generated by Django 2.2.1 on 2019-08-07 13:20
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('catalog', '0006_gene_taxonomy'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='gene',
+            name='gene_length',
+            field=models.PositiveIntegerField(),
+        ),
+    ]

backend/metagenedb/apps/catalog/models/gene.py

@@ -5,7 +5,7 @@ from .function import Function
 
 class Gene(models.Model):
     gene_id = models.CharField(max_length=100, unique=True, db_index=True)
-    gene_length = models.IntegerField()
+    gene_length = models.PositiveIntegerField()
     functions = models.ManyToManyField(Function)
     taxonomy = models.ForeignKey(
         'Taxonomy', related_name='genes',