django-mapped-fields 0.0.3

Form fields to make it easier to map CSV or JSON files to your own models

Django Mapped Fields
====================

A set of form fields to make it easier to accept semi-structured data with variable (but expected) keys. This data can now be mapped directly to your own Django Models and Forms with normalised field names.

A common use case would be to take CSV or JSON files from external systems and
normalise them into your own data structures.


Usage
-----

To use a map field, simply import it and set its `field_names` when creating the
field.

```python
from django import forms

from mapped_fields import fields


class ContactCsv(forms.Form):
"""Import a Contact from a CSV File.
"""
first_name = fields.Charfield(
max_length=50, field_names=('FirstName', 'Forename'))
last_name = fields.Charfield(
max_length=50, field_names=('LastName', 'Surname'))
phone_number = fields.CharField(
max_length=30, field_names=('Telephone', 'Mobile'))


def map_from_csv():
csv_files = [
{
'FirstName': 'Anne',
'LastName': 'Other',
'Mobile': '555-1234',
},
'Forename': 'David',
'Legal Surname': 'Anderson',
'Telephone': '555-2345',
},
]

valid_form = ContactCsv(data=csv_files[0])
valid_form.is_valid() == True
valid_form.cleaned_data['first_name'] == 'Anne'
valid_form.cleaned_data['last_name'] == 'Other'
valid_form.cleaned_data['phone_number'] == '555-1234'

invalid_form = ContactCsv(data=csv_files[1])
invalid_form.is_valid() == False # Legal Surname is not in the mapped fields
```

Handling Multiple field_names in a single file
----------------------------------------------

If you have multiple different fields in the same file mapping to a single
output, the first match on field_names will be used:

```python
from mapped_fields import fields


class ContactForm(forms.Form):
"""Demonstrate multiple field_names.
"""
name = fields.CharField(
max_length=100, field_names=('Name', 'ContactName'))


def map_from_dict():
data = {
'ContactName': 'James',
'Name': 'Anderson',
}

form = ContactForm(data=data)
form.is_valid() == True
form.cleaned_data['name'] == 'Name' # Name was listed first in field_names
```

This is potentially useful if you are importing file formats that are
inconsistent, and where you want a fallback if the "best" header isn't
there.


Fields
------

The Mapped Fields plugin works by extending existing django fields. The
currently supported fields are:

- `mapped_fields.fields.BooleanField`
- `mapped_fields.fields.NullBooleanField`
- `mapped_fields.fields.CharField`
- `mapped_fields.fields.DateField`
- `mapped_fields.fields.DateTimeField`
- `mapped_fields.fields.DecimalField`
- `mapped_fields.fields.FloatField`
- `mapped_fields.fields.IntegerField`
- `mapped_fields.fields.EmailField`
- `mapped_fields.fields.SlugField`
- `mapped_fields.fields.URLField`


All fields work as in Django, but take a mandatory extra argument `field_names` -- a list or tuple
of field names to map from the source data into the field.


Testing
-------

To test, install the requirements inside your virtualenv then run test
inside test_project:

```
virtualenv venv
. venv/bin/activate
pip install -r requirements.txt
python setup.py install

cd test_project
./manage.py test
```