Subproperties

[Maierhofer_Bernd]

with TStringField.Create(Self) do

begin

  FieldName := 'Country.Name';

  Dataset := AureliusDataset1;

end;

and

  [Association([], [])]
    [JoinColumn('LicenseID', [], 'LicenseID')]
    [Description('')]
    FCountry: TCountry;

What happens if the property COUNTRY is not assigned, because it allows NULL?

Accessign via FieldByName('country.name').asstring leads to an AV for me.

[wlandgraf (Wagner Landgraf)]

It should be handled smoothly by the dataset. If Country is nil, FieldByName().AsString would return an empty string.

[Maierhofer_Bernd]

Hmm. This

adsSoftware.entityfieldbyname('licenseid').AsEntity<TLicense>.Description

leeds to an AV when licenseid is not assigned, otherwise it is ok.

This

 adsSoftware.fieldbyname('licenseid.description').AsString

always leads to "field ... not found".

[wlandgraf (Wagner Landgraf)]

@Maierhofer Bernd

Hmm. This
adsSoftware.entityfieldbyname('licenseid').AsEntity.Description
leeds to an AV when licenseid is not assigned, otherwise it is ok.

It's expected, as you are retrieving a TLicense instance using AsEntity, and *then* you are trying to access the Description property. You'd have to check if AsEntity<TLicense> is nil first.

@Maierhofer Bernd

This
adsSoftware.fieldbyname('licenseid.description').AsString
always leads to "field ... not found".

In this case you have to create the licenseid.description field. If it's not created, you get that message. Isn't it your field "licenseiddescrition"?

You can also set 

adsSoftware.SubPropsDepth := 1;

To ask for dataset to create all those sub properties fields automatically for you.