ColdFusion Tag Parameters Can Be Included In Separate Files (Thanks Mark Drew!)
Posted June 17, 2009 at 9:06 AM
At the New York ColdFusion User Group a few weeks ago, Mark Drew was presenting on Reactor, an ORM framework. In his presentation, he was discussing how the SQL was generated and he had something on a slide that I don't think I had ever seen before. He had a CFQuery tag in which the SQL was defined in an included file (via CFInclude). Now, I've seen that done before (separate SQL); but, what I had not seen before that I can remember is that the included SQL file contained actual CFQueryParam tags.
From what I could remember, things like this were not possible. So, I figured it was time to run some experiments. I took three ColdFusion tags that usually have some sort of child parameter tag and tried moving them to separate include files. I did this with CFQuery (to replicate Mark's idea), CFMail, and CFHTTP.
To start with, I wanted to replicate Mark's demonstration using CFQuery and included CFQueryParam tags:
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- <!--- Create a query to test with. --->
- <cfset dataTable = queryNew( "id", "cf_sql_integer" ) />
-
- <!---
- Run query against data table, but build query in
- secondary file.
- --->
- <cfquery name="records" dbtype="query">
- <cfinclude template="cfquery_params.cfm" />
- </cfquery>
-
- <!--- Output query data. --->
- <cfdump
- var="#records#"
- label="Query Data"
- />
... and here is the include file:
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- SELECT
- id
- FROM
- dataTable
- WHERE
- id = <cfqueryparam value="1" cfsqltype="cf_sql_integer" />
The above code runs with no ColdFusion errors.
Then, I tried using the CFMail tag:
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- <!--- Send email, but define body elements in included files. --->
- <cfmail
- to="ben@bennadel.com"
- from="blog@bennadel.com"
- subject="Child Params Test"
- type="html">
-
- <cfinclude template="cfmail_params.cfm" />
- </cfmail>
... and here is the include file:
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- <!--- HTML mail data. --->
- <cfmailpart type="text/html">
- <strong>HTML data.</strong>
- </cfmailpart>
-
- <!--- Text-only mail data. --->
- <cfmailpart type="text/plain">
- Text-only data.
- </cfmailpart>
-
- <!--- Include a file. --->
- <cfmailparam
- file="#ExpandPath( './cfmail_params.cfm' )#"
- type="text/plain"
- />
The above code runs with no ColdFusion errors.
Then, I tried using the CFHTTP tag:
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- <!--- Make HTTP request, but include params in separate file. --->
- <cfhttp
- result="httpResponse"
- method="get"
- url="http://www.google.com/search"
- useragent="firefox">
-
- <cfinclude template="cfhttp_params.cfm" />
- </cfhttp>
-
- <!--- Output http response. --->
- <cfoutput>
- #httpResponse.fileContent#
- </cfoutput>
... and here is the include file:
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- <cfhttpparam
- type="url"
- name="q"
- value="hot sexy female muscle"
- />
This also executed without any ColdFusion errors.
So, that's pretty cool. I am not sure how often it would make sense to use this kind of strategy; but, I was a bit surprised that it worked. I always thought that these child ColdFusion tags needed to be defined in the direct context of their parent tags, but I guess I was totally wrong. Thanks Mark!
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Reader Comments
Interesting post Ben. I've actually done something very similar to your CFMail example, but not the CFHTTP or CFQuery ones. Hmm.
I've used this in the past with <cfquery> -- it's great for keeping a shared "where" clause separate from the main query.
But, does this work with <cfform> ... <cfinput> ... </cfform> too? That limitation used to be there, and it was the main reason I never started using those tags.
Ben
@Ben,
I've never really gotten into CFForm, so I can't say. But, it would seem like it should follow the same scheme.
I've always equated includes (in any language) as Server-Side copy and paste. When I'm teaching people that are having problems understanding how to use includes, I tell them to just pretend that you copy everything from the include and paste it into the parent document. This falls right in line with that way of thinking, though I didn't know that CF would consider it valid :-).
@Daniel,
Yeah, I thought it would be a compile-time validation issue. I'll have to do some more playing around.
Very interesting. Not sure if there's a chance that I will use it - but very interesting.
Ben, I always find good cf tips on your site.
Definitely an interesting technique, but I've been mulling it over for the past several minutes and I can't come up with a situation where you would want to do something like this. Can you see a use for this, Ben?
@Pat,
Thanks my man :)
@Brian,
The SQL is the only one that really makes much sense to me. I can't really think of another reason to do this... unless you were going to create custom tags that wrapped around the inherent tag functionality... assuming that scenario is even still functional. I'll play around.
One possible use that came to mind was building a query testing tool: you'd have a directory of include files with different SQL statements and just loop through them to make sure they worked properly.
The oddness of it just really bothers me for some reason. The normal approach is to create a reusable function and then inject different parameters to get different results, whereas this lets you create reusable parameters to inject into different functions...bit of a mind-bender.
@Brian,
Yeah, it's a bit interesting, right?
I've also done this with nested custom tags in the ColdExt project, with a bit of trickery looking through the list of parent tags you can safely ignore standard CF tags (including cfinclude) and only pass data back to a parent tag that belongs to your own library (using cfassociate), even when the code is in separate files as you've noted here. The built-in CF tags which are generally used as nested tags must treat cfinclude (and other flow control tags) the same way when passing data back to their parent tags :)
Whoah. Weird. It shows how literal cfinclude is.
I've always considered cfinclude to do just that, take another template and insert it right here.
One exception though and I haven't tested this in a while, but I think that a cfinclude inside of cfoutputs does not recognize that it is inside those. The included template must have its own cfoutput tags.
@Matt, I believe you're right, I think the page is executed separately from what I recall.
and, yes, this works just fine with CFFORM tags wrapped around something like CFINCLUDE template="_form.cfm" ...
