I'm trying to write a method that accepts a column(field) name as a parameter and returns the appropriate field entity (ie. MyTableFieldIndex.Id). The following code doesn't work but kind of shows what I'm getting at:

private static IEntityField FindMyTableField( string FieldName )
{
    IEntityField sortField;

    switch( FieldName )
    {
        case "Id": default:
        {
            sortField = (IEntity)MyTableFieldIndex.Id;
            break;
        }
        case "Name":
        {
            sortField = (IEntity)MyTable;
            break;
        }
...

         return sortField;  
    }

}

I know I'm using IEntityField incorrectly since it won't compile as is. I've tried passing through a generic object with no luck either. Any ideas?

Are you looking for a way to create new fields or is this a method inside an entity ? If it's the latter, you can use myEntity.Fields[name] to retrieve a field. Otherwise you could use System.Enum.Parse and get the enum value back for a "EntityFieldIndex.FieldName" string, and that enum you can then use to fabricate a new entity field using the EntityFieldFactory class

Otis wrote:

Are you looking for a way to create new fields or is this a method inside an entity ? If it's the latter, you can use myEntity.Fields[name] to retrieve a field. Otherwise you could use System.Enum.Parse and get the enum value back for a "EntityFieldIndex.FieldName" string, and that enum you can then use to fabricate a new entity field using the EntityFieldFactory class

It's for a method in a manager class I'm trying to create, but I missed the entity.fields[], which would mean I don't need to write my own I don't see a fields collection in my TypedViews, is there an equivalent?

You should call GetFieldsInfo()

(Adapter. SelfServicing doesn't have this method, you should then use: IEntityFields fieldsInResultset = EntityFieldsFactory.CreateTypedViewEntityFieldsObject(TypedViewType.MyTypedView); )

Otis wrote:

You should call GetFieldsInfo()

(Adapter. SelfServicing doesn't have this method, you should then use: IEntityFields fieldsInResultset = EntityFieldsFactory.CreateTypedViewEntityFieldsObject(TypedViewType.MyTypedView); )

I'm using SelfServicing (any reason to switch to adapter?) and I got your second example to work in as far as being able to use a string to look up a field, but I think I'm on the wrong track. I guess I should back up to what I'm actually trying to accomplish.

I basically am trying to setup sort's and predicates so I can pass in a string column name and a value (or sort operator). So instead of

SortClauseFactory.Create( MyTableFieldIndex.Id, SortOperator.Ascending )

I'd have something similar to

SortClauseFactory.Create( FindTable( "Id" ), SortOperator.Ascending )

or

SortClauseFactory.Create( MyTableEntity.Fields[ "Id" ], SortOperator.Ascending )

but I can't get it to compile since the only overloads to the predicate and sort methods use the actual fieldIndexes. Are there any alternatives?

The sortclause factory in fact creates IEntityField objects using the passed in index. It then creates a SortClause object. SO you can just create a SortClause object when you have a field instance

Otis wrote:

The sortclause factory in fact creates IEntityField objects using the passed in index. It then creates a SortClause object. SO you can just create a SortClause object when you have a field instance

Hah, I got it I'm so used to SortClauseFactory.Create

The following works for self servicing

//Method Parameters
IsDescending = true;
SortField = Id;

IEntityFields fields = EntityFieldsFactory.CreateTypedViewEntityFieldsObject(TypedViewType.MyViewTypedView); 

ISortExpression sortBy = new SortExpression( new SortClause( fields[ SortField ], (IsDescending ? SortOperator.Descending: SortOperator.Ascending) ) );

Thanks!

If there anything similar to CreateTypedViewEntityFieldsObject for a TypedList?

I'd like to do the same thing but I'm using TypedList instead of TypedView.

Selfservicing typed lists have a private method BuildResultset(), so at the moment this is not doable, unless you alter the template to make the method public or the generated code.

I'll add it to the to-do list to make this method public and also his friend BuildRelationSet().

Otis wrote:

The sortclause factory in fact creates IEntityField objects using the passed in index. It then creates a SortClause object. SO you can just create a SortClause object when you have a field instance

I decided to try this in an adapter implementation. I can retrieve the IEntity2 object, but the SortClause constructor takes an IEntity object, so I'm stuck.

How would I acheive a dynamic sort expression (or predicate) built around a string column name like above for adapter?

You have to use the second constructor of the SortClause class, which takes an IEntityFieldCore object (which is implemented by the Adapter entityField objects) and a fieldpersistenceinfo object, just set this to null, like the factory does too, and of course the sort operator.

Okay, now I'm stuck on how to create a predicate expression using the above techniques. I'm still using adapter and I'm trying to put together a Like expression (but I will use other expressions in the future). I don't know how to construct a predicate expresison without using PredicateFactory and that doesn't take IEntityField2 objects (unless I'm missing something)?

The predicate factory creates FieldCompareValuePredicate, FieldCompareRangePredicate, FieldLikePredicate etc. instances. These classes all accept an IEntityField instance. The predicate factory create a new field instance for you. You can however create that instance yourself using the EntityFieldFactory, or use an existing field, for example when you already have an instance of an entity (which has fields ).

Please examine the generated PredicateFactory code, it perhaps gives you more insights

Otis wrote:

The predicate factory creates FieldCompareValuePredicate, FieldCompareRangePredicate, FieldLikePredicate etc. instances. These classes all accept an IEntityField instance. The predicate factory create a new field instance for you. You can however create that instance yourself using the EntityFieldFactory, or use an existing field, for example when you already have an instance of an entity (which has fields ).

Please examine the generated PredicateFactory code, it perhaps gives you more insights

I think I understand (it works anyway). Here's the code I came up with (if anyone's interested)

DataTable dt = new DataTable();
string searchValue = "My search text";
MyTypedView view = new MyTypedView();
IEntityField2 field = view.GetFieldsInfo()[ searchField ];

RelationPredicateBucket bucket = new RelationPredicateBucket();
bucket.PredicateExpression.Add( new FieldLikePredicate(field, null, "%" + searchValue + "%") );

adapter.FetchTypedView( vew.FetFieldInfo(), dt, bucket, 0, null, false );

The FieldLikePredicate takes an IEntityFieldCore as a parameter, I'm guessing that that is compatible with both the IEntityField and IEntityField2?

The FieldLikePredicate takes an IEntityFieldCore as a parameter, I'm guessing that that is compatible with both the IEntityField and IEntityField2?

Yes, both interfaces derive from that interface