ACF core principles

While the mvc.lua code provides a generic framework for any lua "mvc"-based application, "acf" is the component that makes the mvc.lua framework into a web configuration Application. Some ideas and rationales for application-wide settings are discussed here.
= Use of cfe =
A cfe (Configuration Framework Entity) is a way to pass data between a model, controller and view in a common way. There are many ways to do this (e.g. closures, AKClass); use of cfe is an arbitrary decision just to keep development moving forward.
A cfe is a table with some fields guaranteed to exist. It is also a way to abstract user-modifiable data from view-centric HTML input types. ACF isn't necessarily web-only. With a different controller and views, it could be cli (or gui?!). The acf-cli application is an example of this.
== Fields in all cfes ==
cfe's are constructed from a function in mvc.lua that returns an anonymous table with the following fields
Field	Default	Description
value	"" 	The value of the cfe (e.g. the IP address, hostname, password, etc.)
type 	"text" 	The type of entity (see below)
label	"" 	User-readable label for the value
The reason for having these fields pre-defined is to allow models, controllers and views to use the indexes without having to first check if they exist. For example the entity will always have a value and type.
cfe's can have other fields. Some common fields that may, or may not, be present:
Field 	Description
errtxt 	Text explaining why validation failed
option 	A list of options for this value
descr 	User-readable description for the value
seq 	Numeric sequence suggesting display order for cfe's in a group or form
default 	Default value (can be displayed to user)
readonly	If present, indicates that the information is to be displayed, but not editable, typically used in forms
To set fields or overwrite field defaults, specify a table in the argument list to the cfe constructor:
:mycfe = cfe({label="User", value="asdf", errtxt="Invalid User"})
is equivalent to
:mycfe = {label="User", value="asdf", type="text", errtxt="Invalid User"}
== cfe types ==
The type field of a cfe can be one of the following:
type 	Description 	Modifiers
text 	a text field, typically one line of text 	
longtext 	a multi-line text field, like a textarea 	
select 	a select list 	value is the currently selected item option is an array of select options
multi 	a multi-select list 	value is an array of selected items option is an array of select options
list 	a list 	value is an array of strings
boolean 	true or false 	
raw 	raw binary data 	
form 	a set of cfe's that make up a form 	value is a table of cfe's that make up a form (the table should be name-indexed)option is the command name to save changes (button name for HTML)descr or errtxt may contain the result of a save attempt
group 	a set of cfe's that make up an anonymous group 	value is a table of grouped cfe's (can be used to pass several items to a view) (the table should be name-indexed)
structure	a Lua table with no further type info 	
password 	a password which should not be readable by a user 	
hidden 	a hidden field typically containing information used by ACF and not visible to a user	
= The Model defines the object set =
The model is responsible for writing and reading from the running system. The model typically does not need to know which part of a specific acf module it is running under. It is not mandatory that the model be lua "oop" as the rest of the system is. (the model may not have any need to know "self")
Since the model can choose how much or how little of the system to expose, the basic data set should be defined in the model.
Category:ACF