MapperKernel Class

The mapper also supports a DeleteLockExpression property allowing the delete lock condition to be specified in meta-data. The DeleteLockExpression is a javascript expression, typically including field references, that is evaluated with each row to initialize its DeleteLocked value.

For row-level record locking, see RowLocked.

Generally extensions used across multiple mappers derive from the MapperExtensionKernel class whereas those that are intended for use on a single mapper derive from an application-specific generated class derived from the TypedMapperExtension template class. Extensions derived from TypedMapperExtension can only be used on the intended mapper, but provide a type-safe, easier to use implementation. These are the most common type of extension in most applications. The more primitive, but flexible MapperExtensionKernel-derived extension are typically used for non-mapper specific functionality such as in the ReadableAudit extension. Virtually all platform-provided extensions are of this type.

Note that since this is a copy of the session's PageInfo object, you should not modify this instance of the PageInfo object. If you want to modify the PageInfo object for this mapper instance only then you should clone the PageInfo object using Clone(IAppContext) and set it back on the mapper as in the example below:

Examples

PageInfo    info = mapper.PageInfo.Clone(cxt);

info.TextItems.Add("Caption", "My Caption");
mapper.PageInfo = info;

Note that a field will be locked for all the static reasons (e.g. if the Locked attribute is set), or if the field is row-locked, or if the mapper is row-locked and the field's IgnoreRowLock property is not set. Note that the IgnoreRowLock property applies only to mapper-level row locking and has no impact on field-level row locking.

The mapper also supports a RowLockExpression property allowing the row lock condition to be specified in meta-data. The RowLockExpression is a javascript expression, typically including field references, that is evaluated with each row to initialize its RowLocked value.

For row-level delete locking, see DeleteLocked.

Although the View is required, you can configure the mapper to used a Stored Procedure instead of the view by specifying the QuerySQL property. If the QuerySQL property is specified, the View will be ignored (but the Studio will still require it. Note that View can be overridden on a page-by-page basis using a page's PageView property.

You should not call MoveFirst prior to calling MoveNext to loop through records in a mapper as this will result in the first record being skipped (unless of course you want to skip the first record). Immediately following a Requery(RequeryHints) the mapper will already be positioned BOF and you can simply loop by calling MoveNext. If you are using a BiDirectional mapper and need to perform subsequent MoveNext loops, call MoveBOF to position just prior to the first data row before starting each subsequent MoveNext.

You should not call MoveFirst prior to calling MoveNext to loop through records in a mapper as this will result in the first record being skipped (unless of course you want to skip the first record). Immediately following a Requery(RequeryHints) the mapper will already be positioned BOF and you can simply loop by calling MoveNext. If you are using a BiDirectional mapper and need to perform subsequent MoveNext loops, call MoveBOF to position just prior to the first data row before starting each subsequent MoveNext.