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reading a reflexive association in a recursive way for grails and groovy

nils — Sun, 29 Nov 2009 16:22:51 +0000

Imagine you have a Menu with multiple items, those items have multiple items and so on. The Menu Items also depend on a Role a User has in the Application Context like ‘ROLE_ADMIN’, ‘ROLE_COOK’, ‘ROLE_SOME’ …
I think the best practice is to save the menu items as a reflexive association in a database table like this:

class MenuItem {
 
    Long id;
    String label;
    Boolean topLevel;
    Integer position;
 
    static hasMany = [roles:Role, childs:MenuItem]
    static belongsTo = [parent:MenuItem]
 
    static mapping = {
        topLevel type:'true_false'
        childs sort:'position'
    }
    static constraints = {
    }
 
    String toString() {
        "[MenuItem id: ${id}, label: ${label}, pos: ${position}]"
    }
 
}

so lets initialize some dummy menu Items:

def file =new MenuItem(label:'file', position:1,topLevel:true,parent:null, roles:[[somerole,cookrole,adminrole]).save();
def view =new MenuItem(label:'view', position:2,topLevel:true,parent:null, roles:[cookrole,adminrole]).save();
def help =new MenuItem(label:'help', position:2,topLevel:true,parent:null, roles:[someroleadminrole]).save();
def logout =new MenuItem(label:'logout', position:2,topLevel:true,parent:null, roles:[somerole,cookrole,adminrole]).save();

those 4 toplevel MenuItems have different roles assiciated with them, for example the view menu can only be accessed by a user wich has the cookrole or the adminrole. the roles have also the property of a level as a number which is zero for an admin user and one for a role which has less rights than the admin. the algorithm then extracts the hightest role from a user instance.
so lets insert some submenus to the database table:

new MenuItem(label:'save File', position:1,topLevel:false,parent:file, roles:[[somerole,cookrole,adminrole]).save();
new MenuItem(label:'save All Files', position:2,topLevel:false,parent:file, roles:[[somerole,cookrole,adminrole]).save();
def serivces = new MenuItem(label:'services', position:3,topLevel:false,parent:file, roles:[[somerole,cookrole,adminrole]).save();
new MenuItem(label:'capture Image', position:1,topLevel:false,parent:serivces, roles:[[somerole,cookrole,adminrole]).save();
new MenuItem(label:'send As Email', position:2,topLevel:false,parent:serivces, roles:[[somerole,adminrole]).save();

notice that the last menu item (send As Email) is not accessible for the cookrole
We now have a three dimensional menu like this:

file
- save File
- save All Files
- services
  - capture Image
  - send As Email
view
help
logout

here is the code to render this menu structure in a controller and send it to the view:

class MainController {
 
    def authenticateService
    def testUser = null
    def menuItems = [:]
 
    void populateMenuItems(map,hightestRole){
 
        //fill the first time with topLevel Items
        if(menuItems.isEmpty()){
            map.each({
                    if(it.roles.contains(hightestRole))
                        menuItems[it] = [:]
            })
        }
 
        menuItems.each({ mi ->
 
                MenuItem.findAllByParent(mi.key).each({ subMi ->
 
                        if(subMi.roles.contains(hightestRole)){
                            mi.value[subMi] = [:]
 
                            findMore( mi.value[subMi],subMi)
                        }
                })
 
        })
    }
 
    void findMore(mapEntry,mi){
 
        def moreItems = MenuItem.findAllByParent(mi)
 
        if(!moreItems.isEmpty()){
 
            moreItems.each({
                    mapEntry[it] = [:]
                    findMore(mapEntry[it],it) //recursive call
            })
 
        }
    }
 
    def index = {
 
        def hightestRole = null
        def principal = (testUser != null)? testUser : authenticateService.principal();
        def itRole
 
        principal.getAuthorities().each({
 
                itRole = Role.findByAuthority(it.authority)
 
                if(hightestRole == null || ( hightestRole != null && itRole.level < hightestRole.level))
                    hightestRole = itRole
 
        })
 
        populateMenuItems( MenuItem.findAllByTopLevel( true, [sort: 'position', order: 'asc'] ), hightestRole )
 
        return [
                    highestRole:hightestRole,
                    menuItems:menuItems,
                    user: principal
                ]
    }
}

the function populateMenuItems calls the function findMore which calls itself recursively as long as a submenu for some item exists.

here are some integation tests for this:

def miSaveFile = MenuItem.findByLabel('save File')
def miSendAsEmail = MenuItem.findByLabel('send As Email')
 
def user = User.get(2)
assertEquals "bestcook", user.username
 
controller.testUser = user;
def model =  controller.index()
 
assertEquals "bestcook", model["bestcook"]?.username
assertEquals Role.findByAuthority("ROLE_COOK"),model["highestRole"]
assertFalse SearchNestedHash.search(model, miSendAsEmail)
assertTrue SearchNestedHash.search(model, miSaveFile)

the SearchNestedHash class is explained in my previous article.

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recursive search on a nested (multidimensional) collection for groovy

nils — Sat, 28 Nov 2009 01:35:21 +0000

you can search for any object in a nested list containing hash’s and lists recursively, check out the tests for examples:

here are the tests:

class SearchNestedHashTests extends GrailsUnitTestCase {
    protected void setUp() {
        super.setUp()
    }
    protected void tearDown() {
        super.tearDown()
    }
    void testHashMap(){
 
            def map = [
                            'x' , 'y', 's'
                         ]
 
            assertTrue SearchNestedHash.search(map,'x')
 
            def a = 'a'
            def b = false
            def c = 1
 
            map= [
                        [[a,b] : c] : 'y'
                   ]
 
            assertTrue SearchNestedHash.search(map,a)
            assertTrue SearchNestedHash.search(map,b)
            assertTrue SearchNestedHash.search(map,c)
            assertTrue SearchNestedHash.search(map,false)
 
            map = [
                           'y' : 'null'
                       ]
 
            assertFalse SearchNestedHash.search(map,'x')
 
            map = [
                           'x':'null'
                       ]
 
            assertTrue SearchNestedHash.search(map,'x')
 
            map = [
                        ['n' : 'y'] : 'x'
                    ]
 
            assertFalse SearchNestedHash.search(map,'t')
            assertFalse SearchNestedHash.search(map,null)
            assertTrue SearchNestedHash.search(map,'x')
 
            map= [
                        ['n' : 'x'] : 'y'
                    ]
 
            assertTrue SearchNestedHash.search(map,'x')
 
            map = [
                        ['x' : 'n'] : 'y'
                    ]
 
            assertTrue SearchNestedHash.search(map,'x')
 
            map= [
                        [['x':'z'] : 'n'] : 'y'
                    ]
 
            assertTrue SearchNestedHash.search(map,'x')
 
            map= [
                        [['c':'x'] : 'n'] : null
                    ]
 
            assertTrue SearchNestedHash.search(map,'x')
 
            def x = ['a':'b']
 
            map= [
                        [['y': x ] : null] : 'y'
                    ]
 
            assertTrue SearchNestedHash.search(map,x)
 
            map= [
                        [['y': ['a':'b'] ] : null] : 'y'
                    ]
 
            assertTrue SearchNestedHash.search(map,x)
 
            map= [
                        [['s':'x'] : null] : 'y'
                    ]
 
            assertTrue SearchNestedHash.search(map,'x')
 
            def crazyMap = [
                        [['c':'v'] : [['c':[['c':[[[[['xxsxx':'v'] : [['c':[['c':[[[          'X'            :'v']:'v']:'v']]:'v']]:'v']]:'v']:'v']:'v']]:'v']]:'v']] : 'y'
                    ]
 
            assertFalse SearchNestedHash.search(crazyMap,'q')
            assertFalse SearchNestedHash.search(crazyMap,'x')//only the capital X is inside
            assertTrue  SearchNestedHash.search(crazyMap,'X')//only the capital X is inside
            assertTrue  SearchNestedHash.search(crazyMap,['xxsxx':'v'])
 
     }
}

here is the Class:

class SearchNestedHash {
    static def found = false;
 
    static synchronized search(collection,targetObj){
        found = false;
        return searchRec(collection,targetObj)
    }
 
    static synchronized searchRec(collection, targetObj){
 
        if(collection instanceof List && collection.contains(targetObj))
            return true
 
        collection.each({
 
                if(
                    (
                        collection instanceof Map
                        &&
                        (
                            it.key == targetObj ||
                            it.value == targetObj ||
                            it.key    instanceof List && it.key    .contains(targetObj) ||
                            it.value instanceof List && it.value .contains(targetObj)
                        )
                    )
                        ||
                    (
                        it instanceof List && it == targetObj
                    )
 
                ){found = true;return}
            })
 
        if(!found){
 
            collection.each({
 
                    if(it.key instanceof Map)
                    searchRec(it.key,targetObj)
 
                    if(it.value instanceof Map)
                    searchRec(it.value,targetObj)
 
                    if(it instanceof List)
                    searchRec(it,targetObj)
 
                })
 
        }
        return found
    }
 
}

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working with time periods

nils — Tue, 09 Sep 2008 13:49:39 +0000

this here is my Dates class with some usefull methods for working with time periods.
For example

getEveryDayBetween
countDays
convert from String to GregorianCalendar and vice versa
getOverlay
isBetweenOrExactlyEqual

here is the source

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best way through a truth table

nils — Tue, 19 Aug 2008 15:56:31 +0000

suppose you have a “truth table” which looks like this for example:

with this algorithm you can get from the left to the right side of the table
by switching the true Boolean values next to each other. It calculates the number
of row switches down to the minimum possible !!!
the Alg. is recursive but it’s not deterministic when in a column is no true Boolean value at all.
In the above picture the alg switches only one time to get from the left to the right side.

It works like this (really abstract):

it builds this table by making maps and lists
the loop starts at the most left side of every row in the table and checks for the column value
count the occurrences of unbreaked true values from step 2
if a false value is detected the counting of the true values before is saved in x and the counter is resetted.
get the maximum x in the whole table. this one result y is then one of the best ways.
delete the columns included in y from the table.
if the table has more columns go back to point 2.

in my alg i work with calendar dates as columns and row numbers.
most of the comments are in German, ask me if you like a translation.

here

this is just a innerclass not the actual one, please implement this in your own class…

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xml for mysql for radius for coovachilli because hibernates 2nd datasource was weak :(

nils — Mon, 18 Aug 2008 18:33:58 +0000

when i tried to add another datasource to the hibernate environment i ran into problems (connection timed out)… i now use the xml way which i talk about earlier … well i didn’t want to install mysql 6 because its just in the alpha release. so i wrote this little cgi script. later when mysql 6 is stable I will use the LOAD XML function. This has the big benefit that i don’t have to open the 3306 … which was dirty but fast anyway.

the privileges: “insert, update, select, ALTER ROUTINE, CREATE ROUTINE, EXECUTE, File” are needed.

This script here can insert and update data in the tables via xml:

here is the format of the xml files for input:

some new name
7

….

tttttttttttt
tttttt
…

…

for getting data this here is possible:

for getting the rows when somebody was online, put the parameters ‘actTime’ with the condition Value yyyy-mm-dd hh:mm and for the ‘type’ put the Value ‘getActionsInTime’, than you get something like this:







2008-09-01 19:34:01
username
10.1.0.114
User-Request
16731
2008-09-02 00:12:52

....

i haven’t figured out how to get rid of the row and field tags…from a mysql command.
To get Rows from the radacct table for a specific user put ‘getActions’ as type and set the Value
for the parameter ‘UserName’.

BE WARNED THERE SOME HIGH SECURITY RISKS BY IMPLEMENTING THIS SCRIPT, I CAN NOT BE MADE RESPONSIBLE FOR ANYTHING HAPPENING BECAUSE OF THIS SCRIPT.

here

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höchste Zahl im Array, biggest Value Array

nils — Tue, 18 Dec 2007 06:38:23 +0000

int biggestNumber=0,temp=0;

for (i = 0; i < someArray.length – 1; i++) {
temp = someArray[i];
if (biggestNumber <= temp)
biggestNumber = temp;
}

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ListenVorgänger vergleichen

nils — Mon, 08 Oct 2007 15:40:35 +0000

Wenn ListenElemente unterschiedlich sind soll eine andere Aktion im gegensatz zur normalen ausgeführt werden.

Liste = 1,2,3,4,4,4,4,6,5,5,3,2,5,7,8,8,9,9, (zufällig, objekte möglich, quasi alles was verglichen werden kann)

y=null //leeres Element

foreach(Obj x : Liste)

if(y==null) y=x;

if(x.equals(y)){

normalAction();

} else{

WennElementNichtGleichDemVorgängerIstAktion();
y=x;

}

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