3.5. if

[if type field op* compare*]

The Interchange Tags Reference has more information on the [if] tag.

named attributes: [if type="type" term="field" op="op" compare="compare"]

[if !type field op* compare*]

named attributes: [if type="!type" term="field" op="op" compare="compare"]

Allows the conditional building of HTML based on the setting of various Interchange session and database values. The general form is:

        [if type term op compare]
        [then]
                                    If true, this text is printed on the document.
                                    The [then] [/then] is optional in most
                                    cases. If ! is prepended to the type
                                    setting, the sense is reversed and
                                    this text will be output for a false condition.
        [/then]
        [elsif type term op compare]
                                    Optional, tested when if fails.
        [/elsif]
        [else]
                                    Optional, printed on the document when all above fail.
        [/else]
        [/if]

The [if] tag can also have some variants:

        [if explicit]
        [condition] CODE [/condition]
                                    Displayed if valid Perl CODE returns a true value.
        [/if]

Some Perl-style regular expressions can be written:

        [if value name =~ /^mike/i]
                                    This is the if with Mike.
        [elsif value name =~ /^sally/i]
                                    This is an elsif with Sally.
        [/elsif]
        [elsif value name =~ /^barb/i]
        [or value name =~ /^mary/i]
                                    This is an elsif with Barb or Mary.
        [elsif value name =~ /^pat/i]
        [and value othername =~ /^mike/i]
                                    This is an elsif with Pat and Mike.
        [/elsif]
        [else]
                                    This is the else, no name I know.
        [/else]
        [/if]

While the named parameter tag syntax works for [if ...], it is more convenient to use the positional syntax in most cases. The only exception is when you are planning to do a test on the results of another tag sequence:

This will not work:

   [if value name =~ /[value b_name]/]
       Shipping name matches billing name.
   [/if]

Do this instead:

   [if type=value term=name op="=~" compare="/[value b_name]/"]
       Shipping name matches billing name.
   [/if]

As an alternative:

   [if type=value term=high_water op="<" compare="[shipping noformat=1]"]
       The shipping cost is too high, charter a truck.
   [/if]

There are many test targets available. The following is a list of some of the available test targets.

config Directive

The Interchange configuration variables. These are set by the directives in the Interchange configuration file.

            [if config CreditCardAuto]
            Auto credit card validation is enabled.
            [/if]

data database::field::key

The Interchange databases. Retrieves a field in the database and returns true or false based on the value.

            [if data products::size::99-102]
            There is size information.
            [else]
            No size information.
            [/else]
            [/if]
        
            [if data products::size::99-102 =~ /small/i]
            There is a small size available.
            [else]
            No small size available.
            [/else]
            [/if]

If another tag is needed to select the key, and it is not a looping tag construct, named parameters must be used:

            [set code]99-102[/set]
            [if type=data term="products::size::[scratch code]"]
            There is size information.
            [else]
            No size information.
            [/else]
            [/if]

discount

Checks to see if a discount is present for an item.

            [if discount 99-102]
            This item is discounted.
            [/if]

explicit

A test for an explicit value. If Perl code is placed between a [condition] [/condition] tag pair, it will be used to make the comparison. Arguments can be passed to import data from user space, just as with the [perl] tag.

            [if explicit]
            [condition]
                $country = $ values =~{country};
                return 1 if $country =~ /u\.?s\.?a?/i;
                return 0;
            [/condition]
            You have indicated a US address.
            [else]
            You have indicated a non-US address.
            [/else]
            [/if]

The same thing could be accomplished with [if value country =~ /u\.?s\.?a?/i], but there are many situations where this example could be useful.

file

Tests for the existence of a file. This is useful for placing image tags only if the image is present.

            [if file /home/user/www/images/[item-code].gif]
            <IMG SRC="[item-code].gif">
            [/if]
        
            or
        
            [if type=file term="/home/user/www/images/[item-code].gif"]
            <IMG SRC="[item-code].gif">
            [/if]

The file test requires that the SafeUntrap directive contain ftfile (which is the default).

items

The Interchange shopping carts. If not specified, the cart used is the main cart. This is usually used to test to see if anything is in the cart. For example:

          [if items]You have items in your shopping cart.[/if]
        
          [if items layaway]You have items on layaway.[/if]

ordered

Order status of individual items in the Interchange shopping carts. Unless otherwise specified, the cart used is the main cart. The following items refer to a part number of 99-102.

          [if ordered 99-102] ... [/if]
            Checks the status of an item on order, true if item
            99-102 is in the main cart.
        
          [if ordered 99-102 layaway] ... [/if]
            Checks the status of an item on order, true if item
            99-102 is in the layaway cart.
        
          [if ordered 99-102 main size] ... [/if]
            Checks the status of an item on order in the main cart,
            true if it has a size attribute.
        
          [if ordered 99-102 main size =~ /large/i] ... [/if]
            Checks the status of an item on order in the main cart,
            true if it has a size attribute containing 'large'.
            THE CART NAME IS REQUIRED IN THE OLD SYNTAX. The new
            syntax for that one would be:
        
            [if type=ordered term="99-102" compare="size =~ /large/i"]
        
            To make sure it is the size that is large and not another attribute,
            you could use:
        
            [if ordered 99-102 main size eq 'large'] ... [/if]
        
          [if ordered 99-102 main lines] ... [/if]
              Special case -- counts the lines that the item code is
              present on. (Only useful, of course, when mv_separate_items
              or SeparateItems is defined.)

scratch

The Interchange scratchpad variables, which can be set with the [set name] value [/set] element.

            [if scratch mv_separate_items]
            Ordered items will be placed on a separate line.
            [else]
            Ordered items will be placed on the same line.
            [/else]
            [/if]

session

The Interchange session variables. Of particular interest are logged_in, source, browser and username.

validcc

A special case, it takes the form [if validcc no type exp_date]. Evaluates to true if the supplied credit card number, type of card and expiration date pass a validity test. It performs a LUHN-10 calculation to weed out typos or phony card numbers.

value

The Interchange user variables, typically set in search, control or order forms. Variables beginning with mv_ are Interchange special values and should be tested and used with caution.

variable

See Interchange Variable values.

The field term is the specifier for that area. For example, [if session frames] would return true if the frames session parameter was set.

As an example, consider buttonbars for frame-based setups. You might decide to display a different buttonbar with no frame targets for sessions that are not using frames:

   [if session frames]
       [buttonbar 1]
   [else]
       [buttonbar 2]
   [/else]
   [/if]

Another example might be the when search matches are displayed. If using the string [value mv_match_count] titles found, it will display a plural result even if there is only one match. Use:

   [if value mv_match_count != 1]
       [value mv_match_count] matches found.
   [else]
       Only one match was found.
   [/else]
   [/if]

The op term is the compare operation to be used. Compare operations are the same as they are in Perl:

   ==  numeric equivalence
   eq  string equivalence
   >   numeric greater-than
   gt  string greater-than
   <   numeric less-than
   lt  string less-than
   !=  numeric non-equivalence
   ne  string equivalence

Any simple Perl test can be used, including some limited regex matching. More complex tests should be done with [if explicit].

[then] text [/then]

This is optional if not nesting "if" conditions. The text immediately following the [if ..] tag is used as the conditionally substituted text. If nesting [if ...] tags, use [then][/then] on any outside conditions to ensure proper interpolation.

[elsif type field op* compare*]

named attributes: [elsif type="type" term="field" op="op" compare="compare"]
Additional conditions for test, applied if the initial [if ..] test fails.

[else] text [/else]

The optional else-text for an if or if-item-field conditional.

[condition] text [/condition]

Only used with the [if explicit] tag. Allows an arbitrary expression in Perl to be placed inside, with its return value interpreted as the result of the test. If arguments are added to [if explicit args], those will be passed as arguments in the [perl] construct.

[/if]

Terminates an if conditional.