yamlhttpforms/README.md

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# HTTP forms defined in YAML
This module allows creating simple interfaces to forms/payloads for use in HTTP POST requests by defining them in highly readable and easily maintainable YAML files.
## Form definition
A form is defined by its fields.
A field is defined by an **alias** (for internal use) and the field's **name**, which is the parameter name in the payload sent during a `POST` request, and which typically corresponds to the `name` attribute of a `<select>` or `<input>` HTML tag.
Optionally, a field can have a **default** value, value **options** (as `<select>` tags do), and may be declared **required** (i.e. non-optional).
A form definition in YAML format will consist of the field aliases as top-level keys, and the corresponding fields' definitions as key-value-pairs below them.
## Example
### Definition
```yaml
# definition.yaml
field1:
name: payload_param_1
field2:
name: payload_param_2
default: foo
choice_field:
name: payload_param_3
options:
value1: text for option 1
value2: text for option 2
default: value1
mandatory_field:
name: payload_param_0
required: true
```
### Usage
```
>>> from yamlhttpforms import load_form
>>> form_interface = load_form('definition.yaml')
>>> form_interface.get_payload(field1='abc', field2='bar', mandatory_field='420')
{'payload_param_1': 'abc', 'payload_param_2': 'bar', 'payload_param_3': 'value1', 'payload_param_0': '420'}
>>> form_interface.get_payload(field1='abc', choice_field='baz', mandatory_field='420')
Traceback (most recent call last):
...
ValueError: "baz" is not a valid option for <SelectField: name="payload_param_3", default="value1", options={'value1': 'text for option 1', 'value2': 'text for option 2'}>
```