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How to create a computed field with the value coming from a display method

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Posted on by FS-16071301-0

Hi guys,

To provide you some context, I have a form AMDeviceTable in which i have displayed a field coming from a display method that was created under the AMDeviceTable table class extension, please see below:

// Display method to extract year from Date
[SysClientCacheDataMethodAttribute(true)]
display HERoutYear HERoutYear()
{
AMDeviceTableMaster deviceTableMaster;

// Get the current record's
deviceTableMaster = this.AMDeviceTableMaster();

// Check if DeRegistrationDate is available
if (deviceTableMaster.DeRegistrationDate)
{
return int2str(year(deviceTableMaster.DeRegistrationDate));
}
// If DeRegistrationDate is empty, check EndDate in AMRentDevice
else if (this.rentalEndDate())
{
return int2str(year(this.rentalEndDate()));
}
// If both DeRegistrationDate and EndDate are empty, check HerEstimatedRentEndDate in AMDeviceTable
else if (this.HerEstimatedRentEndDate)
{
return int2str(year(this.HerEstimatedRentEndDate));
}

Additionally, i wanted to expose this field on my data entity AMDeviceOverviewEntity. Therefore, i have created a virtual field and called my display method result under the postLoad() method on the entity (as stated in MS documentation). However, virtual fields do not allow filtering in Excel OData. After some research i found on MS documentation that i should use computed fields instead but i am not able to achive that goal. I tried the below code but i am getting a build error.

str fldMyField = SysComputedColumn::returnField(tableStr(HERDeviceOverviewEntity),
tableStr(AMDeviceTable), methodStr(HERAMDeviceTableDbt_Extension, HERoutYear));

return fldMyField;

Could you please help me fixing the issue?

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Martin Dráb on at

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How to create a computed field with the value coming from a display method

This is impossible. A computed column method is used to generate SQL code; the display method does nothing like that and it can't be called from SQL either.

You'd have to rewrite X++ code of HERoutYear() to SQL and then write a computed column method generating this SQL code.
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Bharani Preetham Pe... on at

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How to create a computed field with the value coming from a display method

As you are using some functions in x++, this display method cannot be used directly in computed field. I would suggest to write a batch job, create some field and populate that field with batch job code based on this display method and use that in entity.
FS-16071301-0 on at

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How to create a computed field with the value coming from a display method

Thank you so much for the reply, it makes total sense. Since the value was being correctly displayed on the data entity when i used the virtual field approach is there any workaround to make the filtering of this field work in Excel Odata?
André Arnaud de Cal... on at

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How to create a computed field with the value coming from a display method

Hi Francisco,

You can't filter on a virtual field if it is filled using the postLoad function. The data is already retrieved from the database before this method is executed. Like mentioned by Martin, you would need to rewrite it to SQL or filter the data using Excel worksheet options after refreshing the data.