©2003 Hal Helms, Inc. Variables The Tao that can be told is not the eternal Tao. The name that can be named is no t the eternal Name. —Lao-Tzu

©2003 Hal Helms, Inc.

Variables

The Tao that can be told is not the eternal Tao.The name that can be named is not the eternal Name. —Lao-Tzu

ColdFusion MX Foundations

©2003 Hal Helms, Inc. 2

Data types

Variables have a property called a data type that specifies the type of data that a variable holds– integer– string– decimal number– boolean value– record set



Strong typing

Some languages require that you declare a variable's data type prior to using it– String state = "Indiana"; // Java

Once declared, a variable's data type cannot change– boolean state = true; // illegal!!

– Such languages are called strongly-typed



Strong typing: pros & cons

Pros– allows compiler (most strongly-typed languages are also

compiled languages) to optimize performance

– enforced rigor helpful when dealing with large-scale or complex applications

Cons– slower development



Weak typing

Other languages do not require that you declare a variable's data type prior to using it<cfset state = "Minnesota"> 

Data types can change<cfset state = "Minnesota"> <cfset state = true> <cfset state = 26> 

Such languages are called weakly-typed



Weak typing: pros and cons

Pros– no compile cycle (most weakly typed languages are

interpreted languages)

Cons– easier to make mistakes in overwriting variables– slower execution since all data typing must be done at run

time– harder to maintain code



Compiled languages

Some languages have a separate compile cycle during which several checks are made including checking variables are for valid types, correct naming and scoping of variables, etc.– Java– C#

After the compile cycle is completed, the program can be run

When the program runs, we are said to be in run time



Interpreted languages

Some languages have no separate compile cycle but instead do all checking at run time– ColdFusion– Smalltalk



ColdFusion?

ColdFusion is…– weakly-typed– interpreted



Data types can be simple…

String‘Welcome to Programming Foundations’

Numeric25 50.75

Date{ts '2001-03-30 17:45:43'}

BooleanTRUE FALSE



…or complex

Structure– collection of name/value pairs

Array– numbered collection of other data types (not name/value pairs)

Query result set– return by a <cfquery>

List– Pat, Wesley, Donna, Kathy, Michael, Jim



More on variables

Variables have two important properties– scope: where the variable can be accessed from– lifespan (or span): how long the variable lives



Scopes in ColdFusion

Variables that can be seen by the page that called them as well (including <cfinclude>d files) are called local variables

Variables that can be seen by all pages (including custom tags and <cfmodule>d files) are called global variables



Lifespans in ColdFusion

Most variables live only for a single page request Those that live across multiple

page requests are called persistent

Client

Web server

ColdFusion serverDatabase server



Variable matrix

Scope Spanvariables local page request

request global page requestform global page requestURL global page request

attributes local page requestcaller local page request

CGI global page requestcookie global persistentsession global persistentclient global persistentapplication global persistentserver global persistent



Creating/setting a variable

Method 1 (common)<cfset foo = "bar">

Method 2<cfset SetVariable('foo', 'bar')>



Local scope examples

<cfset thisClass = “ColdFusion MX Foundations”>

<cfset SetVariable(‘isReady’,‘TRUE’)>

<cfset variables.myName = “Hal”>

<cfset myName = "Hal">*

*Unscoped variables are part of the default “variables” local scope



Specifying different scopes

<cfset variables.foo = "bar"><cfset foo = "bar"><cfset session.foo = "bar"><cfset request.foo = "bar"><cfset application.foo = "bar"><cfset server.foo = "bar"><cfset caller.foo = "bar"><cfset SetVariable('client.foo', 'bar')>

same



Form variables

When a form is submitted through the post method, any form fields are placed into the form scope of the form processor (the page set in the form's action property) and can be accessed by that page

<form action="MyPage.cfm" method="post"><input

type="hidden" name="today" value="Monday">

…</form>



URL variables

You can pass variables on a URL in a query string The query string is created by appending a ? to

the URL and then adding name=value pairs separated by an ampersand

<a href="MyPage.cfm?userID=5&permissions=12">

These variables are then accessible to the called page in the URL scope



Displaying variables

Wrap pound signs around a variable and set within <cfoutput> tags<cfoutput>

Hello, there, #yourName#</cfoutput>

You don't need to do this within CF tags and functions (usually)<cfset shipping = “5.00”><cfset total = subTotal + shipping><cfset ArrayAppend(arr, 42)>



The Evaluate() function

Use it when you want to force an evaluation of a name as a variable.

Example:– When you submit a form to a processing page, you get a

variable called form.fieldlist, a list of the form fields…



Evaluate()

<cfloop list=“#form.fieldList#” index=“aFormField”><cfoutput>

#aFormField#</cfoutput>

</cfloop>

What will this produce?



Evaluate()

<cfloop list=“#form.fieldList#”index=“aFormField”><cfoutput>

#Evaluate(‘form.’ & aFormField)#</cfoutput>

</cfloop>

What will this produce?

©2003 Hal Helms, Inc.

Complex Variables

A child of five would understand this.

Send someone to fetch a child of five. —Groucho Marx



Complex data types in ColdFusion

Structure– collection of name/value pairs

Array– numbered collection of data

Query result set– return by a <cfquery>

List– series of tokens and delimiters

Bob,Sue,Frank,Anne 21|257|TRUE|c:\cfusionmx\wwwroot\test



What is a structure?

Set of name/value pairs that all relate to a central topic or idea

ISBN 0345417976

title A Prayer for Owen Meany

author John Irving

publisher Ballantine Books

format Paperback

price 14.00



Why structures?

Organizes related data into a single variable that is simpler to store and manipulate

Provides data encapsulation



Working with structures

1. aStructure.author John Irving

valuestructure-name

ISBN 0345417976


author John Irving


format Paperback

price 14.00

2. aStructure[‘author’] John Irving

keys values

key



Structure limitations

Structures can hold as values…– simple values– arrays– structures– result sets– lists



Create a structure

Method 1<cfset aBook = StructNew()><cfset aBook.ISBN = “287898988”><cfset aBook.title = “A Prayer for Owen Meany”><cfset aBook.author = “John Irving”><cfset aBook.publisher = “Ballantine Books”>



Create a structure

Method 2<cfset aBook = StructNew()><cfset aBook[‘ISBN’] = “287898988”><cfset aBook[‘title’] = “A Prayer for Owen Meany”><cfset aBook[‘author’] = “John Irving”><cfset aBook[‘publisher’] = “Ballantine Books”>



Loop over a structure

Method 1<cfloop

collection="#aBook#" item="aProperty"><cfoutput>

#aProperty# is set to a #aBook[aProperty]#<br></cfoutput>

</cfloop>



Loop over a structure

Method 2<cfloop

collection="#aBook#" item="aProperty"><cfoutput>

#aProperty# is set to a #Evaluate('aBook.' & aProperty)#<br>

</cfoutput></cfloop>



By value

With most variables, a duplicate assignment creates a copy of the value in a memory location

Changes to greeting will not affect myGreeting

"Hello"

greeting

<cfset greeting = "Hello"><cfset myGreeting = greeting>

"Hello"

myGreeting



By reference

With structures only, a duplicate assignment creates a pointer to the same memory location

Changes to book will affect myBook

structure

book

<cfset book = StructNew><cfset myBook = book>

myGreeting



What will Pavorotti be singing?

<cfset aComposer=StructNew()><cfset aComposer.firstName = "Benjamin"><cfset aComposer.lastName = "Britten"><cfset aComposer.work = "Serenade for Tenor, Horn, and Strings">

<cfset concertChoice = aComposer>

<cfset aComposer.firstName = "Eric"><cfset aComposer.lastName = "Idle"><cfset aComposer.work = "Always Look On The Bright Side Of Life">

Today, Mr. Pavarotti will perform "#concertChoice.work#"



Use Duplicate() for by value copies

<cfset aComposer=StructNew()><cfset aComposer.firstName = "Benjamin"><cfset aComposer.lastName = "Britten"><cfset aComposer.work = "Serenade for Tenor, Horn, and Strings">

<cfset concertChoice = Duplicate(aComposer)>

<cfset aComposer.firstName = "Eric"><cfset aComposer.lastName = "Idle"><cfset aComposer.work = "Always Look On The Bright Side Of Life">

Today, Mr. Pavarotti will perform "#concertChoice.work#"



Structure functions

Duplicate()IsStruct()StructClear()StructCount()StructDelete()StructFind()

StructInsert()StructIsEmpty()StructKeyArray()StructKeyExists()StructKeyList()StructNew()StructUpdate()



Duplicate()

<cfset newBook = Duplicate(Book)><cfset Book.price = "548788.99">

newBook.price 14.00

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



IsStruct()

IsStruct(Book) TRUE

<cfset FBrocks = TRUE>

IsStruct(FBrocks) FALSE

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructClear()

StructClear(Book)

IsStruct(Book) TRUE

Book.title error

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructCount()

StructCount(Book) 6

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructDelete()

StructDelete(Book,‘title’) ISBN 0345417976

author John Irving


format Paperback

price 14.00

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructFind()

StructFind(Book,‘title’) A Prayer for Owen Meany

StructFind(Book,‘reserved’) error

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructInsert()

StructInsert(Book,‘reserved’,4)

(The fourth parameter for this function, “allowoverwrite” is optional and defaults to FALSE. This option determines whether StructInsert() should overwrite the value of an existing key value.)

ISBN 0345417976


author John Irving


format Paperback

price 14.00

reserved 4

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructIsEmpty()

StructIsEmpty(Book) FALSE

StructIsEmpty(CD) error

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructKeyArray()

StructKeyArray(Book) ISBNAUTHOR FORMAT PUBLISHER TITLEPRICE

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructKeyExists()

StructKeyExists(Book,‘title’) TRUE

StructKeyExists(Book,‘reserved’) FALSE

StructKeyExists(Z,‘title’) error

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructKeyList()

StructKeyList(Book) “AUTHOR,ISBN,FORMAT,PRICE,PUBLISHER,TITLE”

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructNew()

<cfset Book = StructNew()>

StructIsEmpty(Book) TRUE

IsStruct(Book) TRUE

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



StructUpdate()

StructUpdate(Book,‘price’,16.95) ISBN 0345417976


author John Irving


format Paperback

price 16.95

ISBN 0345417976


author John Irving


format Paperback

price 14.00

Book: a structure



Arrays

Definition: a numbered (or indexed) set of values in 1 to 3 dimensions



Array limitations

Arrays can hold as values…– simple values– arrays– structures– result sets– lists



1-D Arrays

Think of as a single row in a spreadsheet

5362 5557

[1] [2] [3] [4]



2-D Arrays

Think of as multiple rows in a spreadsheet

5362 5557

[1] [2] [3] [4]

5948 52716465 5864

[1]

[2]

[3]



3-D Arrays

Think of as a spreadsheet cube

6265 5461

[1] [2] [3] [4]

5948 52716465 5864

[1]

[2]

[3]

5259 65585948 52716465 5864

5362 55575948 52716465 5864

[1][2]

[3]



Refer to array elements

Use the array name followed by the proper index/es in square brackets

5362 5557

[1] [2] [3] [4]

onedee

onedee[3] 55

5362 5557

[1] [2] [3] [4]

5948 52716465 5864

[1]

[2]

[3]twodee

twodee[3][4] 64



Create a 1-D array

<cfset onedee = ArrayNew(1)><cfset onedee[1] = "57"><cfset onedee[2] = "62"><cfset onedee[3] = "55"><cfset onedee[4] = "53">

5362 5557onedee



Loop over 1-D array

<cfloop from="1" to="#ArrayLen(aCart)#" index="aCol"><cfoutput>

#aCart[aCol]#<br></cfoutput>

</cfloop>



Create a 2-D array

<cfset twodee = ArrayNew(2)><cfset twodee[1][1] = "57"><cfset twodee[1][2] = "62"><cfset twodee[1][3] = "55"><cfset twodee[1][4] = "53"><cfset twodee[2][1] = “71"><cfset twodee[2][2] = “48"><cfset twodee[2][3] = "52"><cfset twodee[2][4] = “59"><cfset twodee[3][1] = “64"><cfset twodee[3][2] = “65"><cfset twodee[3][3] = "58"><cfset twodee[3][4] = “64">

5362 55575948 52716465 5864

twodee



Loop over 2-D array

<cfloop from="1" to="#ArrayLen(aCart)#" index="aRow"><cfloop

from="1" to="#ArrayLen(aCart[aRow])#" index="aCol"><cfoutput>

#aCart[aRow][aCol]# </cfoutput>

</cfloop><br></cfloop>



Unbalanced arrays

Arrays can be “unbalanced”—meaning the number of columns may vary from row to row.

This is a valid CF array:

CF

CF

CF

CF

1

CF

CF

CF

CF

CF

Just for fun, write a loop that produces this array…



Things to look out for

It is easy to “walk off” the end of an array—especially unbalanced arrays.

Make sure the array index exists—or CF will throw an

error.

21 3 4 5

<cfset myArr = anArray[6]>

myArr



Array functions

ArrayAppend()ArrayAvg()ArrayClear()ArrayDeleteAt()ArrayIsEmpty()ArrayLen()ArrayMax()ArrayMin()

ArrayNew()ArrayPrepend()ArraySet()ArraySort()ArraySum()ArraySwap()ArrayToList()



Use array functions on 2-D arrays

Made to work on 1-D arrays 2-D arrays can be thought of as a series of

stacked 1-D arrays

5362 5557

5948 5271

6465 5864

stacked1-D arrays

single2-D array



Use array functions on 2-D arrays

If you want to use array functions on 2-D arrays, point at one of the stacked 1-D arrays by specifying which row you want the function to operate on

Example#ArraySum(twodee[3])#

5362 5557

5948 5271

6465 5864



ArrayAppend()

A: 1-D arrayB: 2-D array

ArrayAppend(A,‘x’)

ArrayAppend(B,‘x’) ERROR

ArrayAppend(B[2],‘x’)

1 2 3 4

2 4 6 8

3 6 9 12

1 2 3 4 x

1 2 3 4

2 4 6 8

3 6 9 12

x



ArrayAvg()

ArrayAvg(A) 2.5

ArrayAvg(B) ERROR

ArrayAvg(B[2]) 5


1 2 3 4

2 4 6 8

3 6 9 12



ArrayClear()

ArrayClear(A) YESArrayIsEmpty(A) YES

ArrayClear(B) YESArrayIsEmpty(B) YES

ArrayClear(B[2]) YESArrayIsEmpty(B[2]) YESArrayIsEmpty(B[3]) NO


1 2 3 4

2 4 6 8

3 6 9 12



ArrayDeleteAt()

ArrayDeleteAt(A,2)

ArrayDeleteAt(B,2)

ArrayDeleteAt(B[2],2)


1 2 3 4

2 4 6 8

3 6 9 12

1 3 4

1 2 3 4

3 6 9 12

1 2 3 4

2 6 8

3 6 9 12



ArrayInsertAt()

ArrayInsertAt(A,3,‘x’)

ArrayInsertAt(B,2,‘x’) ERROR

ArrayInsertAt(B[2],2,‘x’)


1 2 3 4

2 4 6 8

3 6 9 12

1 2 3 4x

1 2 3 4

2 4 6 8

3 6 9 12

x



ArrayIsEmpty()

See ArrayClear() function


1 2 3 4

2 4 6 8

3 6 9 12



ArrayMax()

ArrayMax( A ) 4

ArrayMax( B ) ERROR

ArrayMax( B[2] ) 8


1 2 3 4

2 4 6 8

3 6 9 12



ArrayMin()

ArrayMin(A) 1

ArrayMin(B) ERROR

ArrayMin(B[2]) 2


1 2 3 4

2 4 6 8

3 6 9 12



ArrayNew()

<cfset A = ArrayNew( 1 )>

<cfset B = ArrayNew(2 )>


1 2 3 4

2 4 6 8

3 6 9 12



ArrayPrepend()

ArrayPrepend(A,‘x’)

ArrayPrepend(B,‘x’) ERROR

ArrayPrepend(B[2],‘x’)


1 2 3 4

2 4 6 8

3 6 9 12

1 2 3 4x

1 2 3 4

2 4 6 8

3 6 9 12

x



ArrayResize()

•Resets an array to a specified minimum number. •Used for performance gains on very large arrays



ArraySet()

<cfset ArraySet(A,1,4,2 )>

<cfset ArraySet(B,1,4,2)> ERROR

<cfset ArraySet(B[2],1,4,2)>


1 2 3 4

2 4 6 8

3 6 9 12

2 2 2 2

2 2 2 2



ArraySort()

ArraySort(A,‘numeric’,‘desc')

ArraySort(B,‘numeric,‘desc’) ERROR

ArraySort(B[2],‘numeric,‘desc’)


1 2 3 4

2 4 6 8

3 6 9 12

4 3 2 1

1 2 3 4

8 6 4 2

3 6 9 12



ArraySum()

ArraySum(A) 10

ArraySum(B) ERROR

ArraySum(B[2]) 20


1 2 3 4

2 4 6 8

3 6 9 12



ArraySwap()

ArraySwap(A,3,2)

ArraySwap(B,3,2)

ArraySum(B[2],3,2)


1 2 3 4

2 4 6 8

3 6 9 12

1 3 2 4

1 2 3 4

3 6 9 12

2 4 6 8

1 2 3 4

2 6 4 8

3 6 9 12



ArrayToList()

ArrayToList(A) “1,2,3,4”

ArrayToList(B) error

ArrayToList(B[2],‘|’) “2|4|6|8”


1 2 3 4

2 4 6 8

3 6 9 12



Lists

Definition: a list is a string consisting of meaningful data (or tokens) separated by delimiters



Unlimited delimiters

Delimiters can be any single byte character

a,b,c (comma is default delimiter)

a|b|cmyPage.cfm?a=1&b=17552&c=TRUEabca b c



List limitations

Lists can hold as values…– simple values– lists



Read a value from a list

ListGetAt('a,b,c',2) b



See if a value exists in a list

ListFind(myList,2) TRUE | FALSEListFindNoCase(myList,2) TRUE | FALSE



Set the value of a list element

<cfset myList = "a,b,d"><cfset myList = ListSetAt(myList,3,'c')>



Insert an element into a list

<cfset myList = "a,b,d"><cfset myList = ListInsertAt(myList,3,'c')>



Delete an element from a list

<cfset myList = "a,b,d"><cfset myList = ListDeleteAt(myList,3)>



Loop over a list

<cfset myList = "a,b,d"><cfoutput><cfloop list="#myList#" index="aListElement">

#aListElement#<br></cfloop></cfoutput>



List functions

ListLen()ListPrepend()ListQualify()ListRest()ListSetAt()ListSort()ListToArray()ListValueCount()ListValueCountNoCase()

ListAppend()ListChangeDelims()ListContains()ListContainsNoCase()ListDeleteAt()ListFind()ListFindNoCase()ListFirst()ListGetAt()ListInsertAt()ListLast()



ListAppend()

myNums 25,50,75<cfset myNums = ListAppend(myNums,100,',')>

myNums 25,50,75,100



ListChangeDelims()

myNums 25,50,75<cfset myNums = ListChangeDelims(myNums,'+',',')>

myNums 25+50+75



ListContains()

myWords apple,baker,charlieListContains(myWords,'BAKER',',') 0



ListContainsNoCase()

myWords apple,baker,charlieListContainsNoCase(myWords,'BAKER',',') 2

ListContainsNoCase(myWords,'bak') 2

If you want to find elements (as opposed to sub-strings), use the ListFind() and ListFindNoCase() functions



ListDeleteAt()

myNums 25,50,75<cfset myNums = ListDeleteAt(myNums,2,',')>

myNums 25,75



ListFind()

myWords apple,baker,charlieListFind(myWords,'BAKER',',') 0ListFind(myWords,'baker',',') 2ListFind(myWords,'bak',',') 0



ListFindNoCase()

myWords apple,baker,charlieListFind(myWords,'BAKER',',') 2ListFind(myWords,'baker',',') 2ListFind(myWords,'bak',',') 0



ListFirst()

myWords apple,baker,charlieListFirst(myWords) apple



ListGetAt()

myWords apple,baker,charlieListGetAt(myWords,3) charlie



ListInsertAt()

myNums 25,50,75<cfset myNums = ListInsertAt(myNums,2,37,',')>

myNums 25,37,50,75



ListLast()

myWords apple,baker,charlieListLast(myWords,',') charlie



ListLen()

myWords apple,baker,charlieListLen(myWords,',') 3



ListPrepend()

myNums 25,50,75<cfset myNums = ListPrepend(myNums,12,',')>

myNums 12,25,50,75



ListQualify()

myWords apple,baker,charlie<cfset myWords = ListQualify(myWords,"'",',','ALL')>

myWords 'apple','baker','charlie'



ListRest()

myWords apple,baker,charlieListRest(myWords,',') baker,charlie



ListSetAt()

myNums 25,50,75<cfset myNums = ListSetAt(myNums,3,100',')>

myNums 25,50,100



ListSort()

myNums 25,50,75<cfset numsDown = ListSort(myNums,'numeric','desc',',')>

myNums 75,50,25

myWords apple,baker,charlie<cfset wordsDown =

ListSort(myNums,'textnocase','desc',',')>

myWords charlie,baker, apple



ListToArray()

myWords apple,baker,charlie<cfset arr = ListToArray(myWords)>

arr apple baker charlie



ListValueCount()

myWords apple,baker,charlieListValueCount(myWords,'charlie',',') 1ListValueCount(myWords,'CHARLIE',',') 0



ListValueCountNoCase()

myWords apple,baker,charlieListValueCount(myWords,'charlie',',') 1ListValueCount(myWords,'CHARLIE',',') 1



Query Result Set

Definition: row(s) of values returned by an SQL query



Query a database

<cfquery name=“query_name” datasource=“existing_datasource”>

…SQL Statement…</cfquery>



Query properties

<cfquery datasource="cfsnippets" name="myQ">SELECT center_ID, name, city FROM Centers

</cfquery>

<cfoutput>The columns returned are #myQ.columnList#<cfif myQ.recordCount>

<cfloop query=“myQ”>I am now on row #currentRow#<br>

</cfloop></cfif></cfoutput>



Loop over a query

Use either <cfoutput query=“query_name”>|#column_name#</cfoutput>

or <cfoutput>

<cfloop query=“myQ”>#column_name#

</cfloop></cfoutput>



Get results of one column as a list

Use the ValueList() or QuotedValueList() function

<cfset publishers = ValueList(myQ.publisher)>

publishers Techspedition,Techspedition,Prentice Hall,Addison-Wesley,Sams



Dereference a query value

<cfoutput>Your name is #UserInfo.firstName#

</cfoutput>



Query functions

IsQuery()QueryAddColumn()QueryAddRow()QueryNew()QuerySetCell()QuotedValueList()ValueList()

Documents

©2003 Hal Helms, Inc. Variables The Tao that can be told is not the eternal Tao. The name that can be named is no t the eternal Name. —Lao-Tzu