Add field and widget to support a custom submit button in backend forms

This form will not do a regular save, and instead call a callback
function defined on the field.

4 files changed, 37 insertions, 2 deletions

diff --git a/postgresqleu/util/backendviews.py b/postgresqleu/util/backendviews.py
index 61c29108..d5544265 100644
--- a/postgresqleu/util/backendviews.py
+++ b/postgresqleu/util/backendviews.py
@@ -108,7 +108,7 @@ def backend_process_form(request, urlname, formclass, id, cancel_url='../', save
 
     if request.method == 'POST' and not nopostprocess:
         extra_error = None
-        if allow_delete and request.POST['submit'] == 'Delete':
+        if allow_delete and request.POST.get('submit', None) == 'Delete':
             if instance.pk:
                 if hasattr(instance, 'validate_object_delete'):
                     try:
@@ -141,6 +141,15 @@ def backend_process_form(request, urlname, formclass, id, cancel_url='../', save
         if extra_error:
             form.add_error(None, extra_error)
 
+        # Figure out if a custom submit button was pressed
+        for k, v in request.POST.items():
+            if k.startswith('submit_id_'):
+                # We do!
+                f = form.fields[k[10:]]
+                if f.callback:
+                    f.callback(request)
+                return HttpResponseRedirect(".")
+
         if form.is_valid():
             # We don't want to use form.save(), because it actually saves all
             # fields on the model, including those we don't care about.
diff --git a/postgresqleu/util/forms.py b/postgresqleu/util/forms.py
index 2dc82288..d504e3f3 100644
--- a/postgresqleu/util/forms.py
+++ b/postgresqleu/util/forms.py
@@ -10,7 +10,7 @@ import base64
 from itertools import groupby
 
 from .widgets import InlineImageUploadWidget, InlinePdfUploadWidget
-from .widgets import SelectSetValueWidget
+from .widgets import SubmitButtonWidget, SelectSetValueWidget
 
 
 class _ValidatorField(forms.Field):
@@ -145,6 +145,18 @@ class PdfBinaryFormField(ImageBinaryFormField):
     widget = InlinePdfUploadWidget
 
 
+class SubmitButtonField(forms.Field):
+    def __init__(self, *args, **kwargs):
+        if not kwargs:
+            kwargs = {}
+        self.callback = kwargs.pop('callback', None)
+        kwargs['widget'] = SubmitButtonWidget
+        prefixparagraph = kwargs.pop('prefixparagraph', None)
+        super().__init__(*args, **kwargs)
+        self.widget.label = kwargs.get('label', 'Unknown label')
+        self.widget.prefixparagraph = prefixparagraph
+
+
 class SelectSetValueField(forms.ChoiceField):
     widget = SelectSetValueWidget
 
diff --git a/postgresqleu/util/templates/forms/widgets/submitbutton_widget.html b/postgresqleu/util/templates/forms/widgets/submitbutton_widget.html
new file mode 100644
index 00000000..54607ddd
--- /dev/null
+++ b/postgresqleu/util/templates/forms/widgets/submitbutton_widget.html
@@ -0,0 +1,4 @@
+{%if prefixparagraph%}
+<p>{{prefixparagraph}}</p>
+{%endif%}
+<input type="submit" class="btn btn-default" name="submit_{{widget.attrs.id}}" value="{{label}}" />
diff --git a/postgresqleu/util/widgets.py b/postgresqleu/util/widgets.py
index 26388092..1a390b9d 100644
--- a/postgresqleu/util/widgets.py
+++ b/postgresqleu/util/widgets.py
@@ -138,6 +138,16 @@ class Bootstrap4HtmlDateTimeInput(forms.DateTimeInput):
     template_name = 'forms/widgets/bs4_datetime_input.html'
 
 
+class SubmitButtonWidget(forms.Widget):
+    template_name = 'forms/widgets/submitbutton_widget.html'
+
+    def get_context(self, name, value, attrs):
+        d = super().get_context(name, value, attrs)
+        d['label'] = self.label
+        d['prefixparagraph'] = self.prefixparagraph
+        return d
+
+
 class SelectSetValueWidget(forms.Select):
     option_template_name = 'forms/widgets/select_set_value_option.html'