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Forms Bound

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to a Foundset

A Servoy Form is typically bound to a single database table and the form will always contain a single Foundset object which is bound to the same table. Much of the action in the user interface, such as a user editing data fields, directly affects the form's foundset. Conversely, actions taken on the foundset, such as programmatically editing data, is immediately reflected in the form.

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The loadRecords method is used to directly modify the underlying query that loads PK data. There are several uses.

Load by a

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Single PK

This is the simplest approach, which loads a single recordy by its primary key value.

foundset.loadRecords(123);

Load by PK

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Data Set

This approach simply dictates that a foundset will load records based on specified primary key data.

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Load by

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Another Foundset

This approach is useful to essentially copy the query of another foundset.

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// Foundset size grows dynamically as the Foundset is traversed
foundset.getSize(); // returns 200
foundset.setSelectedIndex(200);
foundset.getSize(); // returns 400 because the foundset loaded the next 200 record pks

Iterating Over

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a Foundset

Often, as part of some programming operation, it is necessary to iterate over part or all of a foundset. There are several approaches to iterating, each having their appropriate usage. In general, a Javascript for or while statement is used to control the flow of execution.

Changing

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the Selected Index

Perhaps the most intuitive approach is to programmatically change the foundset's selected index property. 

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See also the JSFoundset's setSelectedIndex method.

Accessing

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a Record Object

While setting the selected index of the foundset is sometimes necessary, it also contains some overhead and therefore is not always the most efficient way to iterate over a foundset. However, one can iterate in a similar manner, access a record object without changing the selected index of a foundset by using the getRecord method of the foundset.

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See also the JSFoundset's getRecord method.

Accessing Data Provider Values As

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an Array

Sometimes the purpose of iterating over a foundset is to access all of the values for a particular data provider. The most efficient way to do this is to obtain an array of values for the foundset's data provider using the getFoundSetDataProviderAsArray method of the databaseManager API.

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See also the JSFoundset's getFoundSetDataProviderAsArray method.

Using

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the Foundset Iterator

Sometimes there is more than one user working on the same foundset, possibly inserting or deleting records. When iterating on a foundset, it needs to be ensured that the loop neither skips nor processes twice any record due to the foundset modifications occurred from other clients. Thus, in such cases, a secure iterator is needed to perform the iteration on the foundset.

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Foundsets

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and Data Broadcasting

A Foundset may be automatically updated when the client receives a Data Broadcast Event . If the data change affected the table to which the foundset is bound, the foundset will be refreshed to reflect the change.

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The Foundset Updater API is ideal to use for the following situations:

Updating

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an Entire Foundset

This essentially has the effect of issuing a SQL UPDATE statement using the WHERE clause that constrains the foundset. This presents a significant performance advantage over updating records individually. In the example below, a related foundset is updated, meaning all orders belonging to the selected customer will be affected.

var fsUpdater = databaseManager.getFoundSetUpdater(customers_to_orders);
fsUpdater.setColumn('status',101);
fsUpdater.performUpdate();

Updating

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a Partial Foundset

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with Different Values

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for Each Record

The Foundset Updater API can also be used to update part of a foundset. Moreover, unlike the above example, this approach allows for different values for each record. In the example below, the first 4 records (starting from the selected index) are updated by specifying an array of values for each column that is affected.

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var count = 0;
var fsUpdater = databaseManager.getFoundSetUpdater(foundset)
while(fsUpdater.next())
{
	fsUpdater.setColumn('degrees',count++);
}