Dealing with some legacy code we came across a rather annoying situation. We are looping through a query with the <cfoutput query="x"> tag. That query has a column named 'url'. Within that loop we need to check if a key exists within the url scope. Since CF puts a priority on what's in the query over general page scopes I can't use a structKeyExists(url,"key") since as far as CF is concerned at this point, url is a string with the value from the current row of the query.
How can I break out of the query scope and inspect what's in my url?
As a temporary we are using isDefined("url.key"), but I would still like to know if there is a way to break out of the query scope.
Also can't really change the column, or even the column name in the query without a few hours of work tracking down an changing all references to it, so we're going to avoid that if at all possible.
EDIT:
There seems to be some confusion as to how this code is set up, and why the simple solutions don't apply. It would be hard for me to give a thorough example but I will try to clarify the situation.
There are many pages that would count as 'pageA' for the following example. Enough that changing how things work would require a change in scope and investment in time that's just not going to happen in the time allotted.
PageA runs a query with one of the columns being named url, then starts an output loop via cfoutput, inside that loop PageB is included. One PageA may have different variables in the URL scope than another PageA, actually they are the same, but may be named differently(varID=x in one case vid=x in another). Inside of PageB I need to use the value from that url scope, so I want to run through the different possible names (if key 'varID' exists in url, use it, otherwise use 'vid').
This is why I want to "punch through" the query scope to get the url structure, and not the url column from the query. Any other method seems to require modifying the many PageAs.
So the question is not how to solve this problem specifically, as there are many ways to do it, I would just really like to avoid them as they all add a lot of time in implementation and testing. The question remains, is there a way to access the url scope as a variable if url exists as a query column and you are in the query scope.
I thought it might work to create a function that returned the url scope, but upon testing it, even with a local-scoped query (which prevents the function using the query itself) the use of url inside the function is still corrupted:
<cffunction name="getUrlScope"><cfreturn Url /></cffunction>
...
<cfoutput query="x">
<cfif StructKeyExists( getUrlScope() , 'key' )>
<!--- still fails :( --->
There is however an undocumented (meaning unsupported and liable to change) option. If you dump getPageContext() you will see a bunch of functions that do interesting things, including dealing with scopes.
You can use getPageContext().SymTab_findBuiltinScope('URL') to get at the URL scope.
You can also use getPageContext().getCfScopes() to get an array of scopes. I'm not sure if the order is guaranteed fixed but it seems to be [cgi,?,url,form,cookie,?] checking on both CF10 and cflive (CF9), so possibly is.
(In CF8 there was the method getBuiltinScopes, which returned a struct instead of an array - this no longer appears to exist, reinforcing the whole unsupported and changeable nature of these methods.)
On Railo those don't work, but there is getPageContext.UrlScope() and similarly-named functions for the other scopes.
One solution would be to assign the url struct to a new variable outside of the cfoutput tag and then reference that variable instead of url. Example:
<cfset urlScope = url>
<cfoutput query="x">
<cfset keyExists = structKeyExists(urlScope, "key")>
</cfoutput>
My solution for this is always to alias the url column in the query as int
SELECT URL as qURL FROM myTable ...
IF you don't have access to the query (it's a stored precedure or used elswhere etc) you can always use query of a query to reselect it with your alias.
I don't care for the idea of creating a separate reference to URL outside the output - but that would also work. I just want to KNOW what is user input (i.e. comes from the URL or FORM) and what is generated internally (i.e. comes from a query).
Couldn't you move structKeyExists(url,"key") outside of the cfoutput block, and store that into a variable? Or do a structAppend to copy the url struct into another struct named something else?
Another approach is to replace your cfoutput block with a cfloop block.
<cfloop from="1' to = "#YourQuery.recordcount#" index = "idx">
<cfif StructKeyExits(url,"key")>
<cfoutput>
#url.key# is not the same as #YourQuery.url[idx]#
which can also be referenced like this #YourQuery["url"][idx]
etc
Related
Having an issue with the <distributed-cache> tag and Redis.
We have a <partial> Razor view that displays results of a long-running query. We acquire the data from a service injected in using #inject. The data updates very rarely, hence we wrap the content in a <distributed-cache> tag helper, with a long expires-after attribute.
However, when the data is finally updated (in another part of our app), we need to delete that key from the distributed cache, in order to force the page to update on next execution. (It's not possible for us to predict when the data will change - we can only respond to an external event.)
The problem we're having is that, despite having a fixed name attribute, the cache key appears to be impossible to predict. For example <distributed-cache name='_myQuery' vary-by-user='true'> creates a key something along the lines 7/za/Bc/ZRn/MsR/hG69TYTx1LEzqBvlyH1OLJgrpk4= in Redis.
How can I either:
Predict/calculate what the cache key is going to be in redis, so that I can delete it in another part of our application?;
Force the <distributed-cache> tag to ignore the cached value this one time? I know we have the enabled property, because this isn't going to work because the page doesn't know when to invalidate the cache.
After digging into the ASP.NET Core source I've found the CacheTagKey.cs file, which contains the GenerateKey() and GenerateHaskedKey() methods. These methods create the key from a bunch of params, then SHA256 hashes the key and returns base64.
So it looks like I can use this to predict the cache key and solve the issue.
I have a bunch of filter categories represented by checkboxes, right now it's sending the full name + on in the query_params.
/?max%5D=5&Movies=on&Art=on&Outdoors=on
Instead, I'd rather just look for the presence of the key to know it's there. This would make the url a bit shorter for people to copy/paste.
/?max%5D=5&Movies&Art&Outdoors
Or, can I have one category key with all the checkboxes as values?
I think it's not possible by default, you'd have to construct an onsubmit script to build the URL and redirect to it, rather than posting directly to the server. You might be better off leaving it as it is.
When dynamically building SQL queries you often see something like this:
WHEN 1=1 AND title="Example" AND ...
The purpose of the 1=1 is to be able to keep appending AND-statements without having to check if any previous statements exist. Thereby avoiding something like this happening:
WHEN AND title="Example" AND ...
I quite often come across a related issue when building the the attributes/search-query for a GET request. I don't want to keep checking if I need to prepend the attribute with '?' or '&'.
So my question is, is there any 'safe' way for me to add an initial attribute that won't interfere with any potential software on the server side. Assuming I do not have full knowledge of the backend.
Something like:
http://example.com?1=1&title=example
http://example.com?null&title=example
http://example.com?i-am-useless&title=example
Or is this allowed?
http://example.com?&title=example
Is there perhaps a simpler way to solve this?
Make sure the URI-string you want to add parameters to already ends in a '?'. Then for every key-value pair, add 'key=value&' to it. Optionally you can then in the end delete the last character from the resulting string. - Reddit user omepiet
I have a datetime value which comes from the API in this format: 2015-07-07T17:30:00+00:00. I simply want to split it up between the date and time values at this point. I am not using an Active Record model and I prefer not to use an sql database if I can.
The way I have set up the app means that the value is "stored" like this in my view: #search.dining_date_and_time
I have tried two approaches to solving this problem:
Manually based on this previous stackoverflow question from 2012: Using multiple input fields for one attribute - but the error I get is the attribute is "nil" even though I put a "try"
Using this gem, https://github.com/ccallebs/split_date_time which is a bit more recent and seems to be a more elegant solution, but after closely following the doc, I get this error, saying my Search model is not initalized and there is no method: undefined method dining_date' for #<Search not initialized>
This is when instead I put #search.dining_date in the view, which seems to be the equivalent of the doc's example (its not that clear). The doc also says the method will be automatically generated.
Do I need to alter my model so I receive the data from the API in another way? ie. not get the variable back as #search.dining_date_and_time from the Search model for any of this to work?
Do I need an Active Record model so that before_filter or before_save logic works - so i can (re)concatenate after splitting so the data is sent back to the API in a format it understands. Can I avoid this - it seems a bit of overkill to restructure the whole app and put in a full database just so I can split and join date/time as needed.
Happy to provide further details, code snippets if required.
As I am not using a conventional Rails DB like MySql Lite or Postgresql, I found that the best solution to the problem was by using this jQuery date Format plugin: https://github.com/phstc/jquery-dateFormat to split the date and time values for display when I get the data back from the API.
The Github docs were not too expansive, but once I put the simply put the library file in my Rails javascript assets folder, I just had to write a few lines of jQuery to get the result and format I wanted:
$(function() {
var rawDateTime = $('#searchDiningDateTime').html();
// console.log(rawDateTime);
var cleanDate = $.format.date(rawDateTime, "ddd, dd/MM/yyyy");
// console.log(cleanDate);
$('#searchDiningDateTime').html(cleanDate);
var cleanTime = $.format.date(rawDateTime, "HH:mm");
// console.log(cleanTime);
$('#searchTime').html(cleanTime);
});
Next challenge: rejoin the values on submit, so the API can read the data by sending/receiving a valid request/response. (The values can't be split like this when sent to the remote service).
I'm developing a Windows Store App, and need to pass parameters to a x-ms-webview control in one page. The code (won't work, just for illustration) should look like:
In the webview host page:
element.querySelector('#webview').myArray= [1, 2, 3];
And in the web view content page:
var arr = window.external.mayArray;
I've tried to embed the parameters in 'src', or use webview.InvokeScriptAsync(). They seem work. But I guess if there is a better way to do this.
If you need the parameters to be available as the page is being loaded, the passing the values as a query string is the simplest option.
Otherwise:
Use invokeScriptAsync (reference) to call a function within the target document after the load has completed. While it delays the set longer than the query string, it's efficient and allows you to keep executing code and adjusting behavior long after the page has loaded. If you can't use the query string for some reason, I'd suggest this.
If the web application has a way to preload the values you need and store them in a Session, it may work, but requires more planning and careful timing.