How to save a value as part of a Field Validation?

Question

Hi, 
 I have a requirement that I have a fileupload control where I need to set value as NULL whenever the validation fails. The validation I have added is to the fileupload field, so at present whenever I upload a wrong file there will be an error message displayed as I have added a validation specific to the field and manually I need to remove the file and upload the right one. 
 Instead my requirement is something like this, 
 a!fileUpload( 
 label" "File Upload", 
 value: local!fileId, 
 saveInto: local!fileId, 
 validations: { 
 if(fv!files.extension = "png",{"Error to display", a!save(local!fileId,null),"") /* Is something like this possible? or how we can achieve this */ 
 } 
 } 
 The above scenario/question is applicable for a textfeild or any other fields also where we can change the value of the field if the validation fails. 
 Regards, 
 Balaji.R 
 )

Dave Lewis · Accepted Answer

Very simple. You need to configure them in separate locations. You can only set the a!save() functions in the saveInto block, but you can always set them conditionally by putting them in an if(). Validations can only go in the validations block, but they can also be defined with an if(). All you need to do is put the save in an if() with a set of conditions and put the validation in another if() with exactly the same conditions. They'll both be in different parts of the code, but both be true at the same time. Pseudo-code: 
 a!interfaceComponent( 
 label: "Something", 
 ... 
 value: local!someValue, 
 saveInto:{ 
 a!save(local!someTarget, save!value), 
 if(ri!conditions, a!save(local!fileId, null), {}) 
 }, 
 ... 
 validations: if(ri!conditions, "Error to display", "") 
 )

Mike Schmitt · Answer

You wouldn't want to do this anyway. 
 For one thing: if you clear out the value of ri!documentIds_int as soon as an invalid extension is uploaded, then the user will never be able to see any error message you put in the validations parameter - all they will see is that the file upload box will seem to just clear itself out as soon as they've uploaded a file, and you will get bug reports for this since they won't understand. 
 But more importantly: once a document is uploaded to the File Upload field, unless its value is manually cleared out from within the file upload field itself , then that document will be saved to the filesystem upon submission of the form, regardless of whether some other control on the form set its value to Null before submission. I strongly recommend against allowing this to happen. 
 I do agree that the fv!files metadata should be accessible from the saveInto parameter of the File Upload Field (note: April Schuppel ), but in this case I believe you need to take another approach, like just using the straightforward validations.

How to save a value as part of a Field Validation?

Top Replies