Difference between revisions of "ACF mvc.lua example"

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You have two options for creating an MVC based application of your own.
 
You have two options for creating an MVC based application of your own.
  
1. Use the ''dispatch'' function. This is the method used by the web interface and the acf-cli application. The action to be dispatched is passed in a string format ''/prefix/controller/action'' and the input values are passed in as a clientinfo table. Output is written to stdout.
+
1. Use the ''dispatch'' function. This is the method used by the web interface and the acf-cli applicat ... \n
  
2. Use the ''new'' function to load the desired controller and then directly call the controller actions. For handling forms and user input, the application will call the action once to retrieve the form cfe, then fill in the desired input values into the cfe and call the action again to submit the form and perform the desired action. The MVC application is responsible for any user interaction and display of the results.
+
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=== Use the Dispatch method ===
+
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Todo
 
  
=== Use the New method ===
+
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Todo
 
  
 +
[[http://ultra-high-end.com/custom-made.html private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]]
  
 +
== private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm ==
  
{{Obsolete}}
+
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4. Create a dispatch wrapper program, named '''helloworld.lua''' in the current directory:
 
  
  -- Simple CLI based mvc application
+
  [[http://ultra-high-end.com/custom-made.html private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]]
 
-- this is to get around having to store
 
-- the config file in /etc/helloworld/helloworld.conf
 
ENV={}
 
ENV.HOME="."
 
 
-- load the module
 
require("mvc")
 
 
-- create an new "mvc object"
 
MVC=mvc:new()
 
 
-- load the config file so we can find the appdir
 
MVC:read_config("helloworld")
 
 
-- create an application container
 
APP=MVC:new("app")
 
 
 
-- dispatch the request
 
APP.clientdata.hostname=arg[2]
 
APP:dispatch( "", "hostname", (arg[1] or ""))
 
  
-- destroy the mvc objects
+
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APP:destroy()
 
MVC:destroy()
 
  
This application loads the "mvc.lua" framework, creates an mvc "object" named "MVC", then reads the helloworld.conf file to find out where the app dir is (helloworld/app/).  It then loads the '''app-controller.lua''' into a new "application level" object named '''APP'''.  Finally, it sets the clientdata and dispatches the hostname-controller/model pair.
+
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5. Test the application:
+
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# hostname
 
Alpine
 
# lua helloworld.lua no-such-function foo
 
The following unhandled application error occured:
 
 
controller: "hostname" does not have a "no-such-function" action.
 
# hostname
 
Alpine
 
  
  # hostname
+
  [[http://ultra-high-end.com/custom-made.html private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]]
Alpine
 
# lua helloworld.lua update Alline
 
Your controller and application did not specify a view resolver.
 
The MVC framework has no view available. sorry.
 
# hostname
 
Alline
 
  
 +
[[http://ultra-high-end.com/custom-made.html private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]]
  
Note in the second case the hostname ''was'' changed, although the application does not know how to report success.
+
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 +
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== Create a view resolver and view formatter ==
+
[[http://ultra-high-end.com/custom-made.html private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]]
  
The view resolver is a function that returns a function that processes the view. The returned function receives input from the controller and generates the output to be displayed.
+
[[http://ultra-high-end.com/custom-made.html private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]]
  
We will build a very simple view resolver and view processor for our application. Add this to the end of '''helloworld/app/hostname-controller.lua'''
+
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 +
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  local private = {}
+
  [[http://ultra-high-end.com/custom-made.html private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]]
 
private.view = function (f)
 
        if (f.msg) then
 
                print( (f.value or "") .. " is not a valid hostname ")
 
        else
 
                print ("Hostname is currently " .. f.value )
 
        end
 
end
 
 
view_resolver = function (self)
 
        return private.view
 
end
 
  
 
+
[[http://ultra-high-end.com/custom-made.html private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]]
Now we can test:
 
 
 
# lua helloworld.lua update "1 2 3"
 
    1 2 3 is not a valid hostname
 
# lua helloworld.lua update       
 
    is not a valid hostname
 
# lua helloworld.lua update Alpine
 
  Hostname is currently Alpine
 
 
 
 
 
But we have two problems:
 
 
 
1. We now have to make a view resolver and view function for every controller.  If we add a ''date'' setting controller, we'll have to make a view resolver and view function for it, and so on.
 
 
 
2. Perhaps more importantly, view_resolver is now an "action" in our appliction.  Recall that invalid actions are captured, but try this:
 
 
 
  # lua helloworld.lua no_such_action Alpine
 
    The following unhandled application error occured:
 
 
 
    controller: "hostname" does not have a "no_such_action" action.
 
 
 
  # lua helloworld.lua view_resolver Alpine
 
    The following unhandled application error occured:
 
 
 
    ./helloworld/app/hostname-controller.lua:27: attempt to index local 'f' (a function value)
 
    stack traceback:
 
        ./helloworld/app/hostname-controller.lua:27: in function 'viewfunc'
 
        ./mvc.lua:139: in function <./mvc.lua:90>
 
        [C]: in function 'xpcall'
 
        ./mvc.lua:90: in function 'dispatch'
 
        helloworld.lua:23: in main chunk
 
        [C]: ?
 
 
 
 
 
Because view_resolver is an action in the worker table, the '''mvc.lua''' runs it; but it returns a function, not a table, and causes an unhandled exception in the view.
 
 
 
== Move the view resolver to the application level ==
 
 
 
The solution to both problems is to move the view resolver and the view function out of the controller's worker table, into the next higher level, in this case, the application's worker table:
 
 
 
 
 
1. Delete the private.view and view_resolver functions from '''helloworld/app/hostname-controller.lua'''
 
 
 
2. Add the following to '''helloworld/app/app-controller.lua'''
 
 
 
local private = {}
 
 
private.view = function ( controller, action, viewtable )
 
        io.write(string.format("Controller: %s  Action: %s\n",
 
                controller or "", action or ""))
 
        io.write ("Returned a table with the following values:\n")
 
 
 
        for k,v in pairs(viewtable) do
 
                io.write(string.format("%s\t%s\n", k, v))
 
        end
 
end
 
 
view_resolver = function (self)
 
        return function (viewtable)
 
                return private.view (self.conf.controller, self.conf.action, viewtable)
 
        end
 
end
 
 
 
 
 
This creates a more "generic" view, but one that will work for any controller - not just '''hostname'''.
 
 
 
 
 
Now things work as they should:
 
 
 
# lua helloworld.lua update "one two"
 
  Controller: hostname  Action: update
 
  Returned a table with the following values:
 
  value  one two
 
  type    string
 
  msg    Hostname can contain alphanumerics only
 
 
# lua helloworld.lua view_resolver "Alpine"
 
  The following unhandled application error occured:
 
 
 
  controller: "hostname" does not have a "view_resolver" action.
 
 
 
= mvc load & exec special functions =
 
 
 
The '''mvc.lua''' module has a provision for executing code on module load, prior to executing the controller's action, just after executing the controller's action, and on module unload.
 
 
 
This is done with the mvc table in the controller.  To demonstrate, let's add a few functions to '''helloworld/app/app-controller.lua'''
 
 
 
mvc = {}
 
mvc.on_load = function (self, parent)
 
        print ("This is the app controller's on_load function")
 
end
 
 
mvc.pre_exec = function (self)
 
        print ("This is the app controller's pre_exec function")
 
end
 
 
mvc.post_exec = function (self)
 
        print ("This is the app controller's post_exec function")
 
end
 
 
 
mvc.on_unload = function (self)
 
        print ("This is the app controller's on_unload function")
 
end
 
 
Now running our script shows when the functions get called:
 
 
 
# lua helloworld.lua update "Alpine"
 
  This is the app controller's on_load function
 
  This is the app controller's pre_exec function
 
  This is the app controller's post_exec function
 
  Controller: hostname  Action: update
 
  Returned a table with the following values:
 
  value  Alpine
 
  type    string
 
  This is the app controller's on_unload function
 
 
 
We can add mvc functions to a specific controller, as well.  Add this to '''helloworld/app/hostname-controller.lua'''
 
 
 
mvc = {}
 
mvc.on_load = function (self, parent)
 
        print ("This is the hostname controller's on_load function")
 
end
 
 
mvc.pre_exec = function (self)
 
        print ("This is the hostname controller's pre_exec function")
 
end
 
 
mvc.post_exec = function (self)
 
        print ("This is the hostname controller's post_exec function")
 
end
 
 
mvc.on_unload = function (self)
 
        print ("This is the hostname controller's on_unload function")
 
end
 
 
And this happens:
 
 
 
# lua helloworld.lua update "Alpine"
 
  This is the app controller's on_load function
 
  This is the hostname controller's on_load function
 
  This is the hostname controller's pre_exec function
 
  This is the hostname controller's post_exec function
 
  This is the hostname controller's on_unload function
 
  Controller: hostname  Action: update
 
  Returned a table with the following values:
 
  value  Alpine
 
  type    string
 
  This is the app controller's on_unload function
 
 
 
Note that both the ''app'' and ''hostname'' '''on_load''' and '''on_unload''' functions were run, but only the ''hostname'' '''pre_exec''' and '''post_exec''' functions ran.  This is because the pre and post exec functions are run as part of the "action", and the '''dispatch''' function looks in the lowest-level controller for the pre/post_exec function.  Since ''hostname'' now defines those functions, it runs them.
 
 
 
To run both the ''hostname'' and ''app'' pre_exec function, you must arrange for the ''hostname'' pre_exec function to call it's parent pre_exec:
 
 
 
mvc = {}
 
mvc.on_load = function (self, parent)
 
        print ("This is the hostname controller's on_load function")
 
        mvc.parent_pre_exec = parent.worker.mvc.pre_exec
 
end
 
 
mvc.pre_exec = function (self)
 
        mvc.parent_pre_exec (self)
 
        print ("This is the hostname controller's pre_exec function")
 
end
 
 
 
[[Category:ACF]] [[Category:Lua]]
 

Revision as of 03:10, 7 March 2016

Set the hostname with mvc.lua

In this example we will create a simple hostname-setting command-line application using mvc.lua. Once the controller/model are built, you can use the same code to set the hostname via the web with a web-based application controller.


For this example, we will assume you have root access on the linux box you are running on (preferably an Alpine Linux box!)

Get the mvc.lua module

Get the mvc.lua module from the git repository.

wget http://git.alpinelinux.org/cgit/acf-core/plain/lua/mvc.lua

Create a model and controller

Create a file hostname-controller.lua, defining the functions that an "end user" could run. We will only create one action, edithostname, which will be used to read and update the hostname. Since the action makes changes to the system, it naturally takes the form of a 'form':

hostname-controller.lua

-- Controller for editing hostname
local mymodule = {} 

mymodule.edithostname = function (self)
        return self.handle_form(self, self.model.get_hostname, self.model.set_hostname, self.clientdata, "Edit", "Edit Hostname", "Hostname Updated")
end                                   

return mymodule

Create a file hostname-model.lua, defining the model functions to get and set the hostname. We return a cfe table for each function including the form with the one entry for hostname:

hostname-model.lua

-- Model functions for retrieving / setting the hostname
local mymodule = {}

-- Create a cfe defining the form for editing the hostname and containing the current value
mymodule.get_hostname = function(self, clientdata)
        local retval = cfe({ type="group", value={}, label="Hostname" })

        -- Warning - io.popen has security risks, never pass user data to io.popen
        local f = io.popen ("/bin/hostname")
        local n = f:read("*a") or "none"
        f:close()
        n=string.gsub(n, "\n$", "")

        retval.value.hostname = cfe({ value=n, label="Hostname" })

        return retval
end

-- Set the hostname from the value contained in the cfe created by get_hostname
mymodule.set_hostname = function(self, hostnameform, action)
        local success = true

        -- Check to make sure the name is valid
        if (hostnameform.value.hostname.value == "") then
                success = false
                hostnameform.value.hostname.errtxt = "Hostname must not be blank"
        elseif (#hostnameform.value.hostname.value > 16) then
                success = false
                hostnameform.value.hostname.errtxt = "Hostname must be 16 characters or less"
        elseif (string.find(hostnameform.value.hostname.value, "[^%w%_%-]")) then
                success = false
                hostnameform.value.hostname.errtxt = "Hostname can contain alphanumerics only"
        end

        -- If it is valid, set the hostname
        if ( success ) then
                local f = io.open("/etc/hostname", "w")
                if f then
                        f:write(hostnameform.value.hostname.value .. "\n")
                        f:close()
                end
                -- Warning - io.popen has security risks, never pass user data to io.popen
                f = io.popen ("/bin/hostname -F /etc/hostname")
                f:close()
        else
                hostnameform.errtxt = "Failed to set hostname"
        end

        return hostnameform
end

return mymodule

Optionally test the model code (without mvc.lua)

If you want, you can create a test.lua script to validate the model code works on its own:

test.lua

require("mvc") -- Needed for cfe function definition
m=require("hostname-model")

local form = m.get_hostname()
form.value.hostname.value = arg[1] or ""
form = m.set_hostname(nil, form)

if form.errtxt then
        print("FAILED: "..form.value.hostname.errtxt or form.errtxt)
end
form = m.get_hostname()
print(form.value.hostname.value)

You can then test this with:

#lua test.lua "Alpine"
 Alpine
#lua test.lua "Invalid Name"
 FAILED: Hostname can contain alphanumerics only
 Alpine

Add the package to the ACF framework

To make the model and controller work within the ACF mvc.lua framework, we must do several things.

1. Install the ACF core package:

apk add acf-core

Optionally, you can add the entire web-based ACF framework:

setup-acf

2. Modify the ACF configuration file to look in /etc/acf/app/ for additional packages. Edit the /etc/acf/acf.conf file to add the /etc/acf/app/ directory to the appdir comma-separated list:

appdir=/etc/acf/app/,/usr/share/acf/app/

3. Move the model and controller to the new package directory. We will call the package "test":

mkdir -p /etc/acf/app/test
mv hostname-*.lua /etc/acf/app/test

4. Test the new package using the acf-cli application:

# acf-cli /test/hostname/edithostname
result = {}
result["label"] = "Edit Hostname"
result["option"] = "Edit"
result["type"] = "form"
result["value"] = {}
result["value"]["hostname"] = {}
result["value"]["hostname"]["label"] = "Hostname"
result["value"]["hostname"]["type"] = "text"
result["value"]["hostname"]["value"] = "Alpine"
# acf-cli /test/hostname/edithostname hostname=test submit=true
result = {}
result["descr"] = "Hostname Updated"
result["label"] = "Edit Hostname"
result["option"] = "Edit"
result["type"] = "form"
result["value"] = {}
result["value"]["hostname"] = {}
result["value"]["hostname"]["label"] = "Hostname"
result["value"]["hostname"]["type"] = "text"
result["value"]["hostname"]["value"] = "test"

Note that the first case read the existing hostname and the second case updated it. The output of the acf-cli application is a serialized version of the cfe form, which is good for testing but not too useful in real life.

Enable the package in the ACF web interface

1. Add the web-based ACF framework:

setup-acf

2. Configure all users to have access to the new hostname action. Edit "/etc/acf/app/test/hostname.roles" file and add GUEST permission for the edithostname action:

echo "GUEST=hostname/edithostname" > /etc/acf/app/test/hostname.roles

The new action should now be visible by browsing to https://IP-of-host/cgi-bin/acf/test/hostname/edithostname. Obviously you might want to reconsider providing GUEST access to this action, because this allows unauthenticated users to modify your hostname.

3. Add the new hostname action to the ACF menu. Edit "/etc/acf/app/test/hostname.menu" file and add a menu item:

echo "Test Hostname Edit edithostname" > /etc/acf/app/test/hostname.menu

You will need to log off from the ACF interface (or delete the session cookie) before the new menu item will be visible.

Make an MVC based application

You have two options for creating an MVC based application of your own.

1. Use the dispatch function. This is the method used by the web interface and the acf-cli applicat ... \n

private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm

Offers private label cosmetics with custom design. We produce lip balms, serum, creams and more. Easy to buy with eshop. Private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm

[private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]

[private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]

private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm

Offers private label cosmetics with custom design. We produce lip balms, serum, creams and more. Easy to buy with eshop. Private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm

[private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]

[private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]

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Offers private label cosmetics with custom design. We produce lip balms, serum, creams and more. Easy to buy with eshop. Private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm

[private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]

[private label cosmetics, custom made cosmetic, custom made cream, custom lip stick lip balm]

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