Hijacking the ajax callback

[Portal 6]

I've opened a grid based upon Table_One.
The grid has a new column(field) not in Table_One.
Each records' row has a button attached to it.
After entering data into the new column in the grid, when the button Onclick is fired I want to
save the record, including the new column data, to Table_Two which includes the new field.

What code would make an ajax callback and save the record to a different table without changing
the data in the original table. Some of the original field names in Table_One might be different in
Table_Two, so some mapping would be involved.

If coding the button OnClick event, and using the action javascript, and you attach the ajax callback
action, OR use the server-side Xbasic, both of these options return a string of javascript commands
to execute in the Browser. It seems I want to hijack and redirect the ajax callback to update a different
table than the grid is based upon.

[Clipper87]

Re: Hijacking the ajax callback

This is what ajax callback is all about, execute some code on the server and return some js code if needed. Upon calling the callback event you submit the data from grid based on table_one and in the event you open another connection to table two in order to create a record filled with the submitted data from table one. There's no hijacking involved.

[Portal 6]

Re: Hijacking the ajax callback

Frank,
Thanks for the reply.
That is the question, how do you open a second connection to Table_Two.
It seems like the ajax callback is hard wired.
Where do I see the callback code so it can be modified to save the data to Table_Two?

If someone opens a second connection, while allowing the first connection to save the data
to Table_One, what would happen to the extra data from the new column in the grid that does
not have a corresponding field in Table_One?

Am I correct that the first connection must be closed before opening the second? This brings
me back to the original question, how to cancel or recode the first connection to point to
Table_Two?

Thanks,
John

[Clipper87]

Re: Hijacking the ajax callback

John,

Dive into the wiki and read articles like these for a starter:
SQL http://wiki.alphasoftware.com/Learni...ith+SQL+Tables
DBF http://wiki.alphasoftware.com/TABLE.OPEN+Method

[eribla]

Re: Hijacking the ajax callback

Hi

maybe you allow me to hijack your thread.

My issue is that inside of the AJAX callback called "MyCallback" I do some SQL query and get a result in a variable called Result.

Now I want to pass this result back int the Desktop Java realm:

...
...
jscmd = <<%js%
{grid.object}.setValue('G','numberOf',rowNum, Result);
// alert('Result'); -> same issue
%js%

MyCallback = jscmd


Unfortunately I get "unknown variable "Result"".


Mhmm..?

[Clipper87]

Re: Hijacking the ajax callback

Shouldn't you just double quote the javascript that your callback returns ? The first 2 parameters of the setValue method need to be in uppercase not just the first one.

jscmd = "{grid.object}.setValue('G','NUMBEROF',rowNum, Result);"
MyCallback = jscmd

[eribla]

Re: Hijacking the ajax callback

Thanks Frank

No that is not the issue but was rather my typing here.
My issue is how to get any value that a Ajax Callback (XBasic) will fill with a value
back into Java - even an alert will not work.


Eriks

[Clipper87]

Re: Hijacking the ajax callback

The result of your Xbasic callback is some Javascript code that still needs to be executed at the client side, you are feeding the string that contains Javascript into your browser back from the server where is was computed. What exactly are you trying to accomplish ?

[Clipper87]

Re: Hijacking the ajax callback

I did not focus on the setValue method; Result is a variable you obtained from xBasic so you have to build your javascript string as follows:

jscmd = "{grid.object}.setValue('G','NUMBEROF',rowNum, "+Result+");"

If Result is not a character type variable then you'll have to convert it.

PS: Are you an intl developer? If so maybe you can indicate your country in your profile?

[Davidk]

Re: Hijacking the ajax callback

Your javascript command would have to be

MyCallBack = "alert('" + result + "');"

You have to tear down the variables set in the callback and allow them to get resolved when passed out of the callback.

You'd have to do the same for rowNum as well.

[Clipper87]

Re: Hijacking the ajax callback

Or use the {grid.rowNumber} placeholder

[eribla]

Re: Hijacking the ajax callback

Frank

I appreciate your help.
I am relatively new to Alpha web stuff and the one thing that puzzle me most is the one way DATA flow from the client (browser) to the server.

If I do a callback to the server I can do all kinds of things, like calculating stuff that was passed through the e object or doing SQL operations but I have not found a way to get the calculated data back to the browser.

I can do:

if result is 5 then
jscmd ="alert(' result was 5')"
Callback = jscmd

But what about if the result is stored in a variable "myRESULT", that can be anything between 1 and 1000000?
I don't seem to be able to do

jscmd = "alert('result was" + myRESULT + "')"

The string will be fine, but

Callback=jscmd will say "unknown variable"


....

Even worse is the fact that I was told that I just can't use AJAX to get data from the server

Like

JavaCode
JavaCode
Callback -> do something on the server ( SQL Query)
a = Result from Callback

Javacode to do something with a
...
...



Do I have to write everything on the server into a table and then open a new Grid
via callback Javacode that shows the the results?


Thanks

Eriks

PS: I am working and living in the USA but I am from Europe

[Davidk]

Re: Hijacking the ajax callback

Erkik,

This works, so I'm not sure why you're getting an error

Dim myResult as n
Dim jscmd as c
myResult = 5
jscmd = "alert('Here is the result " + myResult + "');"
DisplayVar = jscmd

Sounds like you're not creating and assigning your var in the xbasic code.

As for getting the data back into the grid, the ajax callback provides everything you need by use of the "e" object

e.g.

'If you set certain properties in 'e._set' then the appropriate Javascript code will be automatically generated in the Ajax response
'Examples:
'e._set.lastname.value = "Smith" --- will set the value of the 'Lastnme' field in the current row to "Smith"

So, basically, you're working as a client with the grid... you press a button or do something which fires the ajax callback - stuff gets sent to the server, data gets read... or whatever else you want to do... and you set variables and do calcs. Now... when you're all done you use the "e" object and shove stuff back into the grid. It's elegant.

[eribla]

Re: Hijacking the ajax callback

Thanks David

I will try that, I did not know that the e values can be set on the server side with "e._set.lastname.value" AND will be reflected
in the client grid after returning from the Ajax call.
Must have missed that video...


Since I have you ... hope you don't feel abused..

Where is it explained how the XBasic "string operators" "<<jscmd% " "<<sql%" .. work.

It looks as if they are used to format the strings, but I had a hard time to do this (since I don't understand it"
and jscmd=" ...;" or sql_query= "..." seem to work just fine.

Thanks

Eriks

[Davidk]

Re: Hijacking the ajax callback

I may be mistaken, but I don't think e._set.lastname.value is anything that happens on the server side. The "e" object gets set on the server side, but I believe javascript code is generated that is executed back in the client when controls comes back.

Whenever I see <<jscmd% etc my eyes cross. I haven't really looked it much, but I got the impression that inserting variables was a bit tough to do. Easily coding <<% stuff for javascript and sql is on my list of things to wrap my head around. I usually go with jscmd = "javascript;javascript;javascript;" I can read it and understand it easily... but that's just me and my limitation.