Added a save-on-change flag to allow the automatic updating of objects in the database. Centralised the calls so caching can be used as well (or instead) if desired

Author: Mark Gibbs

README.md

@@ -46,7 +46,7 @@ cd django-plotly-dash
 ## Usage
 
 To use existing dash applications, first register them using the `DelayedDash` class. This
-replaces the `dash.Dash` class of `plotly.py.`
+replaces the `Dash` class of the `dash` package.
 
 Taking a very simple example inspired by the excellent [getting started](https://dash.plot.ly/) documentation:
 

demo/demo/plotly_apps.py

@@ -49,5 +49,6 @@ def callback_size(dropdown_color, dropdown_size):
     [dash.dependencies.Input('dropdown-one','value')]
     )
 def callback_c(*args,**kwargs):
+    da = kwargs['dash_app']
     return "Args are %s and kwargs are %s" %("".join(*args),str(kwargs))
 

django_plotly_dash/dash_wrapper.py

@@ -62,6 +62,16 @@ def as_dash_instance(self):
         '''
         return self.form_dash_instance()
 
+    def handle_current_state(self):
+        'Do nothing impl - only matters if state present'
+        pass
+    def update_current_state(self, wid, key, value):
+        'Do nothing impl - only matters if state present'
+        pass
+    def have_current_state_entry(self, wid, key):
+        'Do nothing impl - only matters if state present'
+        pass
+
     def form_dash_instance(self, replacements=None, specific_identifier=None):
         if not specific_identifier:
             app_pathname = "%s:app-%s"% (app_name, main_view_label)
@@ -266,19 +276,27 @@ def dispatch_with_args(self, body, argMap):
 
         target_id = '{}.{}'.format(output['id'], output['property'])
         args = []
-        for component_registration in self.callback_map[target_id]['inputs']:
-            args.append([
-                c.get('value', None) for c in inputs if
-                c['property'] == component_registration['property'] and
-                c['id'] == component_registration['id']
-            ][0])
 
-        for component_registration in self.callback_map[target_id]['state']:
-            args.append([
-                c.get('value', None) for c in state if
-                c['property'] == component_registration['property'] and
-                c['id'] == component_registration['id']
-            ][0])
+        da = argMap.get('dash_app', None)
 
-        return self.callback_map[target_id]['callback'](*args,**argMap)
+        for component_registration in self.callback_map[target_id]['inputs']:
+            for c in inputs:
+                if c['property'] == component_registration['property'] and c['id'] == component_registration['id']:
+                    v = c.get('value',None)
+                    args.append(v)
+                    if da: da.update_current_state(c['id'],c['property'],v)
 
+        for component_registration in self.callback_map[target_id]['state']:
+            for c in state:
+                if c['property'] == component_registration['property'] and c['id'] == component_registration['id']:
+                    v = c.get('value',None)
+                    args.append(v)
+                    if da: da.update_current_state(c['id'],c['property'],v)
+
+        res = self.callback_map[target_id]['callback'](*args,**argMap)
+        if da and da.have_current_state_entry(output['id'], output['property']):
+            response = json.loads(res.data.decode('utf-8'))
+            value = response.get('response',{}).get('props',{}).get(output['property'],None)
+            da.update_current_state(output['id'], output['property'], value)
+
+        return res

django_plotly_dash/migrations/0003_auto_20180514_1802.py

@@ -0,0 +1,23 @@
+# Generated by Django 2.0.5 on 2018-05-15 01:02
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_plotly_dash', '0002_simple_example_state'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='dashapp',
+            name='save_on_change',
+            field=models.BooleanField(default=False),
+        ),
+        migrations.AlterField(
+            model_name='dashapp',
+            name='base_state',
+            field=models.TextField(default='{}'),
+        ),
+    ]

django_plotly_dash/models.py

@@ -17,6 +17,7 @@ class DashApp(models.Model):
     base_state = models.TextField(null=False, default="{}") # If mandating postgresql then this could be a JSONField
     creation = models.DateTimeField(auto_now_add=True)
     update = models.DateTimeField(auto_now=True)
+    save_on_change = models.BooleanField(null=False,default=False)
 
     def __str__(self):
         return self.instance_name
@@ -36,9 +37,48 @@ def _stateless_dash_app(self):
             setattr(self,'_stateless_dash_app_instance',dd)
         return dd
 
+    def handle_current_state(self):
+        '''
+        Check to see if the current hydrated state and the saved state are different.
+
+        If they are, then persist the current state in the database by saving the model instance.
+        '''
+        if getattr(self,'_current_state_hydrated_changed',False) and self.save_on_change:
+            new_base_state = json.dumps(getattr(self,'_current_state_hydrated',{}))
+            if new_base_state != self.base_state:
+                self.base_state = new_base_state
+                self.save()
+
+    def have_current_state_entry(self, wid, key):
+        cscoll = self.current_state()
+        cs = cscoll.get(wid,{})
+        return key in cs
+
+    def update_current_state(self, wid, key, value):
+        '''
+        Update current state with a (possibly new) value associated with key
+
+        If the key does not represent an existing entry, then ignore it
+        '''
+        cscoll = self.current_state()
+        cs = cscoll.get(wid,{})
+        if key in cs:
+            current_value = cs.get(key,None)
+            if current_value != value:
+                cs[key] = value
+                setattr(self,'_current_state_hydrated_changed',True)
+
+    def current_state(self):
+        cs = getattr(self,'_current_state_hydrated',None)
+        if not cs:
+            cs = json.loads(self.base_state)
+            setattr(self,'_current_state_hydrated',cs)
+            setattr(self,'_current_state_hydrated_changed',False)
+        return cs
+
     def as_dash_instance(self):
         dd = self._stateless_dash_app()
-        base = json.loads(self.base_state)
+        base = self.current_state()
         return dd.form_dash_instance(replacements=base,
                                      specific_identifier=self.slug)
 
@@ -76,8 +116,8 @@ def locate_item(id, stateless=False):
         return da, app
 
 class DashAppAdmin(admin.ModelAdmin):
-    list_display = ['instance_name','app_name','slug','creation','update',]
-    list_filter = ['app_name','creation','update',]
+    list_display = ['instance_name','app_name','slug','creation','update','save_on_change',]
+    list_filter = ['creation','update','save_on_change','app_name',]
 
     def _populate_values(self, request, queryset):
         for da in queryset:

django_plotly_dash/views.py

@@ -42,10 +42,12 @@ def update(request, id, stateless=False, **kwargs):
         # Use direct dispatch with extra arguments in the argMap
         app_state = request.session.get("django_plotly_dash",dict())
         argMap = {'dash_app_id': id,
+                  'dash_app': da,
                   'user': request.user,
                   'session_state': app_state}
         resp = app.dispatch_with_args(rb, argMap)
         request.session['django_plotly_dash'] = app_state
+        da.handle_current_state()
 
     return HttpResponse(resp.data,
                         content_type=resp.mimetype)