It's possible to determine the default value of a SQL Server table field?

I want to initialize an entity using the default values defined in the schema.

I'm using Adapter scenario.

This issue was discussed here: http://www.llblgen.com/TinyForum/Messages.aspx?ThreadID=15323

(edit) Another relevant thread: http://www.llblgen.com/TinyForum/Messages.aspx?ThreadID=17039

Walaa wrote:

This issue was discussed here: http://www.llblgen.com/TinyForum/Messages.aspx?ThreadID=15323

(edit) Another relevant thread: http://www.llblgen.com/TinyForum/Messages.aspx?ThreadID=17039

Yes, but how can I retrieve the default value set in the sql server schema?

When do you want to retrieve the default values? At design time/code generation or at runtime?

Please bare in mind that default values may change inside the database schema, and thus maintaining/synching these changes might be a nightmare.

Walaa wrote:

When do you want to retrieve the default values? At design time/code generation or at runtime?

Please bare in mind that default values may change inside the database schema, and thus maintaining/synching these changes might be a nightmare.

if it were possible at runtime, I could set the default values for a new entity, when the entity is instantiated. BTW, retrieving the default values at code generation time would be also a suitable solution.

P.S. Changing the default values in the schema is extremely rare, and when I change a value, I could regenerate the data layer.

IMHO, you should choose between doing defaults at DB or at runtime. If you choose DB, just create entities and don't fill the values you don't want to, the DB will pull default values to these fields. If you choose in-memory, you can do it into the OnInitialized method mentioned in the first thread posted by Walaa.

daelmo wrote:

IMHO, you should choose between doing defaults at DB or at runtime. If you choose DB, just create entities and don't fill the values you don't want to, the DB will pull default values to these fields. If you choose in-memory, you can do it into the OnInitialized method mentioned in the first thread posted by Walaa.

this does not answer my question, so i think isn't possibile to retrieve the values from the DB (unless I do not use, for example, the sp_columns stored procedure in SQLServer).

I already set default values in memory. I know that not setting the values in my entity, the DB will make the work for me.

But I have a llblgen template to generate the validator classes for all entities. I also have utility methods to validate not nullable fields, and if a field is not nullable but have a default value, the validator doesn't work properly. If I knew that the field has a default value, I could skip it in the validation process.

so I repeat my original question: it's possible to retrieve the default values from the db?

which llblgen pro version: 3.0 or 2.6?

Otis wrote:

which llblgen pro version: 3.0 or 2.6?

3.0

Both versions pull default values from the DB (if possible, not all db's allow it). They're stored in the target field's 'DefaultValue' property. This value is obtainable in .lpt templates, by traversing the fields in the mapping of the entity you're working on.

The default value is however the exact string in the default value property of the table field. This means that if you call a db function there (e.g. GETDATE()), the default value is (GETDATE()).

In an lpt template, obtain the GroupableModelElementMapping object by calling currentProject.GetGroupableModelElementMapping(entity, _executingGenerator.DriverID).

Then traverse the FieldMappings property which contains FieldMapping instances. The MappedTarget is the db field (view/table field) which contains the DefaultValue property.

As said, not all db's retrieve these values. See the catalog explorer whether your fields have indeed default values retrieved from the db.

Otis wrote:

Both versions pull default values from the DB (if possible, not all db's allow it). They're stored in the target field's 'DefaultValue' property. This value is obtainable in .lpt templates, by traversing the fields in the mapping of the entity you're working on.

The default value is however the exact string in the default value property of the table field. This means that if you call a db function there (e.g. GETDATE()), the default value is (GETDATE()).

In an lpt template, obtain the GroupableModelElementMapping object by calling currentProject.GetGroupableModelElementMapping(entity, _executingGenerator.DriverID).

Then traverse the FieldMappings property which contains FieldMapping instances. The MappedTarget is the db field (view/table field) which contains the DefaultValue property.

As said, not all db's retrieve these values. See the catalog explorer whether your fields have indeed default values retrieved from the db.

thank you Otis, I created a lpt template, something like:

<%  foreach(IFieldElementCore field in entityFields)
        {
            var fieldMapping = mapping.GetFieldMappingOfField(field);
            var targetField = fieldMapping.MappedTarget;
            if(targetField.HasDefaultValue) {%>
                ...
            <%}
        }%>

Now i can determine if a default value exists for each field, and skip it in validation. The retrieved value is not usable, because, as you said, is the exact string in SQL Server db.