if
Allows conditional parsing based upon the setting of various Interchange
session and database values.
Summary
- [if type term op compare] ... [/if]
| Parameter
|
Description
|
Default
|
| type |
The type of test you would like to perform. |
None |
| base |
Alias for type. |
None |
| term |
Reference to a value, within the type context. |
None |
| op |
The comparison operator to be used. |
None |
| operator |
Alias for op. |
None |
| compare |
Value to be compared with the term. |
None |
| comp |
Alias for compare. |
None |
| condition |
Alias for compare. |
None |
| hide |
Suppress any output text that would ordinarily be returned from this tag.
(This universal parameter was introduced with Interchange version 5.5.2.) |
No
|
| interpolate |
Parse Interchange tags, included in the body text, before this container tag executes. |
No
|
| reparse |
Process any Interchange tags found in the text output from this tag. |
Yes
|
Examples
Tag expansion example (positional parameters)
[tmpn foo]bar[/tmpn]
[if scratch foo eq "bar"]
Correct - scratch foo is bar. I'd award you a prize if I had one.
[else]
Bzzzt! WRONG! The correct answer is [scratch foo].
You leave with nothing.
[/else]
[/if]
|
|
Correct - scratch foo is bar. I'd award you a prize if I had one.
|
Tag expansion example (named parameters)
[tmpn foo]bar[/tmpn]
[if type="scratch" term="foo" op="eq" compare="bar"]
Correct - scratch foo is bar. Well played!
[else]
Bzzzt! WRONG! The correct answer is [scratch foo].
You are the weakest link... Goodbye.
[/else]
[/if]
|
|
Correct - scratch foo is bar. Well played!
|
Description
This tag allows the conditional building of HTML and/or Interchange tag regions,
based upon the setting of various Interchange session and database values.
The general form is as follows:
[if type term op compare]
[then]
If true then this is shown as part of the document output.
The "then" container is optional in most cases. If ! is prepended
to the type setting, the sense is reversed and this will be output
for a false condition.
[/then]
[elsif type term op compare]
Optional, tested if the initial "if" test fails
[/elsif]
[else]
Optional output when all other tests fail
[/else]
[/if]
|
The [if] tag can also have some variants:
[if type=explicit compare=`$perl_code`]
Output if valid Perl code block returns a true value when executed.
[/if]
|
You can also use the Perl regular expression match syntax:
[if value fname =~ /^mike/i]
This is the if with Mike.
[elsif value fname =~ /^kevin/i]
This is an elsif with Kevin.
[/elsif]
[elsif value fname =~ /^racke/i]
This is an elsif with Racke.
[/elsif]
[else]
Imposter alert!
[/else]
[/if]
|
While the named parameter tag syntax works for [if],
it is more convenient to use positional calls in most cases.
The only exception is if you are planning on doing a test on the results
of another tag sequence:
[if value lname =~ /[value b_lname]/]
Shipping name matches billing name.
[/if]
|
Oops!
That will not work.
You must do this instead:
[if type=value term=lname op="=~" compare="/[value b_lname]/"]
Shipping name matches billing name.
[/if]
|
or better still:
[if type=explicit compare=`$Values->{lname} =~ /$Values->{b_lname}/`]
Shipping name matches billing name.
[/if]
|
Interchange also supports a limited [and] and [or]
capability:
[if value fname =~ /Mike/]
[or value fname =~ /Kevin/]
Your name is Mike or Kevin.
[/if]
[if value fname =~ /Mike/]
[and value state =~ /OH/]
Your name is Mike and you live in Ohio.
[/if]
|
If you need to perform very complex [and] and [or]
operations then you will be better off using [if explicit] or,
better still, using embedded Perl.
Either of these would allow more complex testing and parsing of values.
Test types
The test type is specified using the type parameter.
Any of the types, listed in this section, can be used.
config
The Interchange configuration variables.
These are set by the directives in your Interchange configuration file
(or the defaults).
[if config CreditCardAuto]
Auto credit card validation is enabled.
[/if]
|
cgi
Test CGI variable,
posted into the page with a HTML form,
or via a URI argument.
For example:
[if cgi foo = 1]
You requested foo.
[else]
Please ask for a foo next time.
[/else]
[/if]
|
data
The Interchange database tables.
Retrieves a column in the named table and returns true or false,
based upon 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.
You look more like a XXXXXXL to me.
[else]
99-102 is not available in small.
Never mind, it wouldn't have fit you anyway.
[/else]
[/if]
|
discount
Checks to see if a discount is present for an item.
[if discount 99-102]
Item is discounted.
[/if]
|
errors
Check to see whether there are any error/information
messages associated with a named form value.
[if errors fname]
Please enter your first name.
[/if]
|
explicit
A test for an explicit value.
If Perl code is placed in a [condition] container
then the supplied code will be used to make the comparison.
For example:
[if explicit]
[condition]
return 1 if $Values->{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 previous example was a bit contrived,
as the same effect could be accomplished with the following:
[if value country =~ /u\.?s\.?a?/i]
...
[/if]
|
but you will run into many situations where it is useful.
This will work for Variable values:
[if type=explicit compare="__MYVAR__"]
...
[/if]
|
Note that the compare parameter is equivalent to the
[condition] container, in that both evaluate as Perl code.
That means you need to watch out when you put in user-supplied values,
(so that users can't inject Perl code into your server)
and data from your own variables or tables which may look different than
you expected.
For example, say you're in a loop,
checking whether at least one of the fields "foo" and "bar" has a true
value:
[if type=explicit compare="[loop-param foo][loop-param bar]"]
...
[/if]
|
Most of the time this will work fine.
However, if "foo" contains a string beginning with '0',
such as '0009',
Perl will try to interpret it as an octal number,
where the digit '9' is invalid,
resulting in the following unexpected error in the website's
error.log file:
|
Bad if 'explicit 0009': Illegal octal digit '9' at (eval 155) line 1, at end of line
|
A safer way to check is:
[if type=explicit compare="q{[loop-param foo][loop-param bar]}"]
...
[/if]
|
Although, in that case, your data must not contain a "}".
To be extra safe you can surround your interpolated data with a
[filter] that's appropriate for the quoting method you've chosen.
This code can be useful on a form submission page,
especially if the user is sent back to the form to correct errors:
[if type=explicit compare="[error all=1 show_var=1 keep=1]"]
<b>The following errors were detected in your form submission:</b>
<br>
<blockquote>
[error all=1 keep=1 show_error=1 show_label=1 joiner="<br>"]
</blockquote>
[/if]
|
See the [error] tag for more information.
Also see the errors test, above.
field
This is much like the data test type, listed above,
except that it works on the the table(s) listed in the
DefaultTables local configuration directive.
[if field size::99-102]
There is size information.
[else]
No size information.
[/else]
[/if]
[if field size::99-102 =~ /small/i]
There is a small size available.
You look more like a XXXXXXL to me.
[else]
99-102 is not available in small.
Never mind, it wouldn't have fit you anyway.
[/else]
[/if]
|
file
Tests for the existence of a file.
Useful for placing image tags only if the image is present.
[if type=file term="/path/to/images/[item-code].gif"]
<img src="[item-code].gif">
[/if]
|
file-A
Compares against a file's access time (in days).
[if file-A foofile.ext > 1]
foofile.ext has not been accessed in over a day.
[/if]
|
This is the same as Perl's -A test.
file-B
Compares against a file's binary status.
[if file-B foofile.ext]
foofile.ext is a binary file.
[/if]
|
This is the same as Perl's -B test.
Note that the test only examines the first 1000 bytes or so,
and so it can be fooled.
file-d
Tests whether a file is a directory.
[if file-d foodir/bardir]
foodir/bardir is a directory.
[/if]
|
This is the same as Perl's -d test.
file-e
Tests whether the file (or directory) exists at all.
[if file-e foo/bar]
foo/bar exists
[/if]
|
This is the same as Perl's -e test.
file-f
Tests whether a file is a plain file (follows symbolic links).
[if file-f foo/bar]
foo/bar is a file.
[/if]
|
This is the same as Perl's -f test,
and is the default for [if file].
The following two examples are equivalent:
[if file-f error.log]
error.log is a file.
[/if]
[if file error.log]
error.log is a file.
[/if]
|
file-l
Tests whether a file is a symbolic link.
[if file-l foo/bar]
foo/bar is a symbolic link.
[/if]
|
This is the same as Perl's -l test.
file-M
Tests against the number of days since the file was modified.
[if file-M error.log > 0.5]
There have been no errors in 12 hours.
[/if]
[if file-M error.log < 1]
There have been errors in the last day.
[/if]
|
This is the same as Perl's -M test.
file-r
Tests whether file is readable by the Interchange user.
[if file-r error.log]
We can read the error.log.
[/if]
|
This is the same as Perl's -r test.
file-s
Allows tests against the size of a file.
[if file-s error.log > 1024]
There have been more than a kilobyte of errors.
[/if]
[if file-s error.log < 100000]
There have been than less than 100,000 bytes of errors.
[/if]
|
This is the same as Perl's -s test.
file-T
Tests whether a file is a plain text file.
[if file-T error.log]
error.log is a text file.
[/if]
|
This is the same as Perl's -T test.
Note that the test only examines the first 1000 bytes or so,
and so it can be fooled.
file-w
Tests whether the file can be written to by the Interchange user.
[if file-w error.log]
We can log errors.
[else]
We can't log errors. Call the Coast Guard!
[/else]
[/if]
|
This is the same as Perl's -w test.
file-x
Tests whether the file is executable by the Interchange user.
[if file-x error.log]
error.log is not executable (not that it needs to be).
[/if]
[if !file-x pages]
There is no way to use a page in the pages directory, as it is
not searchable.
[/if]
|
This is the same as Perl's -x test.
global
Configuration variables set using a global
Variable directive.
[if global MV_PAGE eq 'index']
You are on the index page.
[else]
You are not in the index page.
You are on @@MV_PAGE@@.
[/else]
[/if]
|
If you want to test a local Variable,
or a variable set using the local VariableDatabase
configuration directive,
then use this tag's variable parameter.
items
Usually used as a litmus test to see if anything is in the cart,
for example:
If no cart name is specified then "main" will be used.
[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.
If no cart name is specified then "main" will be used.
The following items refer to a part number of 99-102.
Check the status of an item on order (using the default "main" cart).
[if ordered 99-102]
Item 99-102 is in your cart.
[/if]
|
Check the status of an item on order (using the named "layaway" cart).
[if ordered 99-102 layaway]
Item 99-102 is on layaway.
[/if]
|
Check the status of an item on order in the main cart.
Specifically, we are checking whether the ordered item has a "size" attribute.
[if ordered 99-102 main size]
A size was specified for 99-102
[/if]
|
Check the status of an item on order in the main cart.
Specifically, we are checking whether the ordered item's "size" attribute
value contains the word "large".
[if ordered 99-102 main size =~ /large/i]
The size attribute for 99-102 contains "large"
[/if]
|
To make sure it is exactly "large", you could use:
[if ordered 99-102 main size eq "large"]
The size attribute for 99-102 is "large"
[/if]
|
pragma
Test a page Pragma value,
set with the the Pragma directive in the catalog.cfg
file, or with the [pragma] tag.
[if pragma dynamic_variables]
__THE_VARIABLE__
[else]
[data table=variable column=Variable key=THE_VARIABLE]
[/else]
[/if]
|
scratch
Test a scratchpad variables,
previously set with
[set],
[seti],
[tmp] and
[tmpn]
(or not set, as the case may be).
[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]
|
scratchd
This is the same as the "scratch" test type,
except that the variable from the scratchpad after testing.
[if scratchd foo == 1]
Foo was equal to 1, but has now been deleted.
[else]
Foo was not equal to 1.
It has been deleted now so you'll never know what the value actually was.
[/else]
[/if]
|
|
Availability
This test type was introduced in version 5.5.1,
and is therefore not available for use with any earlier Interchange version.
|
session
Test an Interchange session variable.
Of particular interest are
"logged_in",
"username",
"spider" and
"browser".
Other session hash keys include the following:
| Name
|
Description
|
|
| accesses
|
Accesses within the last 30 seconds
|
|
| arg
|
The argument passed in an [area] tag. |
|
| browser
|
The identification value sent by the user agent. |
|
| carts
|
A reference to a Perl hash containing shopping carts.
See $Carts for
more information. |
|
| host
|
Interchange's note of the visitor's hostname
(possibly modified by DomainTail).
If the hostname could not be looked up
(HostnameLookups switched off or
DNS error etc.) then the visitor's IP address will be
stored here instead. |
|
| id
|
The current session ID. |
|
| last_error
|
The last error or status message from the error logging routine. |
|
| last_search
|
The last non-SQL Interchange search specification invoked. |
|
| last_url
|
The current Interchange path_info. |
|
| logged_in
|
Will be true if the user is logged in. |
|
| ohost
|
Interchange's note of the visitor's IP address when using
|
a non-SSL link (also see shost) |
| pageCount
|
Number of unique URIs generated by Interchange for this session. |
|
| payment_result
|
A hash of result messages from payment module
transaction attempts.
See examples in the
Interchange payment modules documentation. |
|
| prev_url
|
The previous path_info. |
|
| referer
|
HTTP_REFERER string. |
|
| ship_message
|
The last error messages from shipping. |
|
| shost
|
Interchange's note of the visitor's IP address when using
|
a SSL link (also see ohost) |
| spider
|
Will be true if the user is a search engine spider. |
|
| source
|
Source of original entry to Interchange. |
|
| teleport
|
Date and time (in
"%Y%m%d%H%M%S" format) for use with the PageTables
directive. |
|
| time
|
Time (seconds since 01 January 1970) of the last access. |
|
| user
|
The REMOTE_USER string. |
|
| username
|
Logged-in username.
See the Interchange user database page. |
|
validcc
A special case which 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.
does a LUHN-10 calculation to weed out typos or phony card numbers.
Uses the standard CreditCardAuto values for targets if
nothing else is specified.
value
Test a form value,
previously set with [value]
or via a previous HTML form post.
An example might be the when search matches are displayed.
If you use the string "[value mv_match_count] titles found",
the following will display a different message if only one match was found:
[if value mv_match_count != 1]
[value mv_match_count] matches found.
[else]
Only one match was found.
[/else]
[/if]
|
variable
Configuration variables set using a local
Variable or VariableDatabase
directive.
[if variable FOO_ALLOWED]
You may foo if you so wish.
[else]
No foos here please.
we are fed up with people fooing around.
[/else]
[/if]
|
If you want to test a global Variable
then use this tag's global parameter.
Sub-tags
[then]
This is optional if you are not nesting if conditions,
as the text immediately following the [if] tag is used
as the conditionally substituted text.
For a usage example, see the description, above.
|
Note
It used to be the case that,
when nesting [if] tags,
you needed to use a [then][/then]
container on any outside conditions to ensure proper interpolation.
This is no longer the case with modern Interchange versions.
|
[elsif type term op compare]
This is an additional condition to test,
which is applied if the initial [if] test fails.
For a usage example, see the description, above.
[else]
This block is output if all other test fail.
For a usage example, see the description, above.
[condition]
This is only used with the [if explicit] test type.
It allows an arbitrary Perl expressions be placed inside,
with its return value interpreted as the result of the test.
See the explicit test type for a usage example.
[and]
This sub-tag can be used to add a simple "and" condition to the [if].
For example:
[if value fname =~ /Mike/]
[and value state =~ /OH/]
Your name is Mike and you live in Ohio.
Don't ask how I knew that.
[/if]
|
[or]
This sub-tag can be used to add a simple "or" condition to the [if].
For example:
[if value fname =~ /Mike/]
[or value fname =~ /Kevin/]
Your name is either Mike or Kevin.
[/if]
|
Parameters
type
This parameter is used to specify the type of test you would like to perform.
Many test types are available.
term
The value of this parameter is treated differently, depending upon the
context provided by the type parameter.
The value referenced by this parameter will be compared with the
compare value.
op
This parameter specifies the compare operator which is to be used.
Compare operators are as in Perl:
| Symbol
|
Description
|
| == |
Numeric equivalence. |
| eq |
String equivalence. |
| > |
Numeric greater-than. |
| >= |
Numeric greater-than or equal to. |
| gt |
String greater-than. |
| < |
Numeric less-than. |
| <= |
Numeric less-than or equal to. |
| lt |
String less-than. |
| != |
Numeric non-equivalence. |
| ne |
String non-equivalence. |
| =~ |
Regular expression match. |
| !~ |
Regular expression non-match. |
Any simple Perl test can be used,
including some limited regex matching.
More complex tests are best done with [if explicit].
compare
This value will be compared with the value referenced by the
term parameter.
