CSV import implemented using CSVFileField

netbox/utilities/forms/fields.py

@@ -26,6 +26,7 @@ __all__ = (
     'CSVChoiceField',
     'CSVContentTypeField',
     'CSVDataField',
+    'CSVFileField',
     'CSVModelChoiceField',
     'CSVTypedChoiceField',
     'DynamicModelChoiceField',
@@ -221,6 +222,77 @@ class CSVDataField(forms.CharField):
         return value
 
 
+class CSVFileField(forms.FileField):
+    """
+    A CharField (rendered as a Textarea) which accepts CSV-formatted data. It returns data as a two-tuple: The first
+    item is a dictionary of column headers, mapping field names to the attribute by which they match a related object
+    (where applicable). The second item is a list of dictionaries, each representing a discrete row of CSV data.
+
+    :param from_form: The form from which the field derives its validation rules.
+    """
+
+    def __init__(self, from_form, *args, **kwargs):
+
+        form = from_form()
+        self.model = form.Meta.model
+        self.fields = form.fields
+        self.required_fields = [
+            name for name, field in form.fields.items() if field.required
+        ]
+
+        super().__init__(*args, **kwargs)
+
+    def to_python(self, file):
+
+        records = []
+        file.seek(0)
+        csv_str = file.read().decode('utf-8')
+        reader = csv.reader(csv_str.splitlines())
+
+        # Consume the first line of CSV data as column headers. Create a dictionary mapping each header to an optional
+        # "to" field specifying how the related object is being referenced. For example, importing a Device might use a
+        # `site.slug` header, to indicate the related site is being referenced by its slug.
+
+        headers = {}
+        for header in next(reader):
+            if '.' in header:
+                field, to_field = header.split('.', 1)
+                headers[field] = to_field
+            else:
+                headers[header] = None
+
+        # Parse CSV rows into a list of dictionaries mapped from the column headers.
+        for i, row in enumerate(reader, start=1):
+            if len(row) != len(headers):
+                raise forms.ValidationError(
+                    f"Row {i}: Expected {len(headers)} columns but found {len(row)}"
+                )
+            row = [col.strip() for col in row]
+            record = dict(zip(headers.keys(), row))
+            records.append(record)
+
+        return headers, records
+
+    def validate(self, value):
+        headers, records = value
+
+        # Validate provided column headers
+        for field, to_field in headers.items():
+            if field not in self.fields:
+                raise forms.ValidationError(f'Unexpected column header "{field}" found.')
+            if to_field and not hasattr(self.fields[field], 'to_field_name'):
+                raise forms.ValidationError(f'Column "{field}" is not a related object; cannot use dots')
+            if to_field and not hasattr(self.fields[field].queryset.model, to_field):
+                raise forms.ValidationError(f'Invalid related object attribute for column "{field}": {to_field}')
+
+        # Validate required fields
+        for f in self.required_fields:
+            if f not in headers:
+                raise forms.ValidationError(f'Required column header "{f}" not found.')
+
+        return value
+
+
 class CSVChoiceField(forms.ChoiceField):
     """
     Invert the provided set of choices to take the human-friendly label as input, and return the database value.