use calculated properties in Flexberry ORM

Nechranice property

If the property Nechranice (marked attribute NotStored), it is not processed data services. Inside the accessor get specify any code (expression) that calculates the value of the property.

Nechranice property and views

The developer should follow closely that in view, which is loading objects data services, got all the properties which depend on the calculated attribute.

Important: Failure to heed this will cause invalid account errors.

service Behavior data using a calculated field

Usually data services with the fix lists not using data objects when the return data as strings. This is done to improve performance, as the savings of computational resources for creating data objects is very high. However, the expression for the computable account of the attribute is specified directly in a property of the data object, so when the data object contains calculated attributes, data services, and in doing so creates a data object, properties oznacavanja under view, then the conversion to a string (because the data service will request the value of a calculated property, runs his account). To avoid account through the data object and, accordingly, to expedite the work of the data services when you are uploading a list, the attribute is applied DataServiceExpression which the property is assigned to the service data expression» «clear this data service. Thus, if the attribute DataServiceExpression specified, the data object is not created, and the account of computable attribute» «is shifted to the service data according to an expression.

Warning: create expression in DSE does not negate that it should be duplicated to GET.

Rules for the use of computable fields

Accepted to the IDs in the expression is clearly distinguished by the symbol @ (dog).

Important: Computable attributes, which imposed authority definitely need to have DataServiceExpression

an Example of a calculated property

[NotStored]
public Деньги Итого 
{ 
    get 
         { 
              return ИтогоДисконт + ИтогоВекселя - СуммаНДС;
         }
}

an Example of a computable property attribute DataServiceExpression

[DataServiceExpression(typeof(SQLDataService),"'\"' @NAME@ '\"'")]
[NotStored] 
public string НАИМЕНОВАНИЕВКАВЫЧКАХ 
{
    get
       {
           return "\""+ НАИМЕНОВАНИЕ+"\"";
       }
}

Example detailov

Example detailov when determining the value of a calculated field is available in Nahranie (computable) properties of the data object.

Primary keys in computable fields

Use primary keys in computable fields by specifying STORMMainObjectKey without the “ @ “ symbol.

For example, in list form, the message “Street has a primary key ".

[ICSSoft.STORMNET.NotStored())
[DataServiceExpression(typeof(ICSSoft.STORMNET.Business.SQLDataService), "\'Street \' @Name@ \' has the primary key \' and CAST(STORMMainObjectKey as varchar(max))"))
public virtual string NotStoredName

When using this property as a craftsman in the sql query STORMMainObjectKey will be correctly replaced by STORMJoinedMasterKey.

('Улица ' + "IIS.TestStandWinforms.Home"."Street.The name" + ' имеет первичный ключ ' +CAST("STORMJoinedMasterKey0" as varchar(max))) as "Street.NotStoredName"

the Use of computable fields in calculated fields

In relation to architectural features generator sql queries in Flexberry ORM, use a calculated field in the calculated fields at the moment not supported.

For example, there is a class Дом master Улица.

The class Улица there is a computable field NotStoredName calculated as follows:

'Улица ' + @Название@ + ' имеет первичный ключ ' +CAST(STORMMainObjectKey as varchar(max))

Suppose that there is a need to use this field when calculating the value of a calculated field class Дом:

'Корпус ' + @Корпус@ + ';' + @Улица.NotStoredName@

However, this option value will not be counted. To implement the required logic, you can paint an expression that calculates the value of the field as follows:

'Корпус ' + @Корпус@ + ';' + 'Улица ' + @Улица.Название@ + ' имеет первичный ключ ' +CAST(@Улица@ as varchar(max))

Example of creating nehrenovo data properties

The process of creating a calculated property using DataServiceExpression is well illustrated by the following task: There is a system of accounting customers, which stores information about their purchases. The purchases can be two statuses: “submitted to the Bank” and “Paid”. You need to determine the buyer computable field “Amount paid”.

First and foremost you must create in Flexberry Designer class diagram.

Field “Somaprescription” class “Buyer” to do all of nagraniem](fo_attributes-class-data.html), and then in DataService attribute Expression this field to add the line:

DataService : ICSSoft.STORMNET.Business.SQLDataService;

DataService Expression:

"SELECT SUM(purchase."Сумма")
FROM "Buyer" customer join "Buy" purchase on customer."primaryKey" = purchase."Buyer"
WHERE purchase."Buyer" = StormMainObjectKey AND purchase.Status = 'Оплачено' "

To generate the code.

Work with program code

Was generated with the following code:

[ICSSoft.STORMNET.NotStored()]
[DataServiceExpression(typeof(ICSSoft.STORMNET.Business.SQLDataService), "SELECT SUM(purchase.\"Amount\")"+
"FROM \"Customer\" customer join \"Purchase\" purchase on customer.\"primaryKey\" = purchase.\"Buyer\""+
"WHERE purchase.\"Buyer\" = StormMainObjectKey AND purchase.\"Status\" = \'Paid\' ")]
public virtual decimal СуммаОплаченныхПокупок
{
	get {	return null;	}
	set {}
}

As a result, when viewing lists of buyers Nechranice field “Somaprescription” is calculated no object creation data.

Note: After editing the object Покупатель in the list of the appropriate buyer in the field СуммаОплаченныхПокупок displays an empty string. One solution to this problem might be for the cached values, which you need to create a private variable that will store the cached value.

public class Покупатель : ICSSoft.STORMNET.DataObject
{
	private ICSSoft.STORMNET.UserDataTypes.NullableDecimal cashedPurchaseSum = null; //variable to cache fields Somaprescription 
	private ICSSoft.STORMNET.UserDataTypes.NullableDecimal cashedAvailableSum = null; //variable to store the cache field Dostupnymi 
	//... 
}

You also need to edit the code for СуммаОплаченныхПокупок.

[ICSSoft.STORMNET.NotStored()]
[DataServiceExpression(typeof(ICSSoft.STORMNET.Business.SQLDataService), "SELECT SUM(purchase.\"Amount\")"+
"FROM \"Customer\" customer join \"Purchase\" purchase on customer.\"primaryKey\" = purchase.\"Buyer\""+
"WHERE purchase.\"Buyer\" = StormMainObjectKey AND purchase.\"Status\" = \'Paid\' ")]
public virtual decimal СуммаОплаченныхПокупок
{
	get
	{
		return this.cashedPurchaseSum;
	}
	set
	{
		if (value != null)
		{
			this.cashedPurchaseSum= value;
		}
	}}

If we extend the problem statement that the “Available amount” of the class “Customer”, you must record the available amount on the account (i.e. the amount in the account minus the amount of payments that has the status “submitted to the Bank”), the code for the field object may have the following form (why this.СуммаНаСчете in the expression written as @Communitcate@ explained in the article Nahranie (computable) properties of the data object):

// *** Start programmer edit section *** (Buyer.Dostupnymi CustomAttributes) 
[DataServiceExpression(typeof(SQLDataService), "SELECT @Communitcate@ - SUM(purchase.\"Amount\") "+
	"FROM \"Customer\" customer join \"Purchase\" purchase on customer.\"primaryKey\" = purchase.\"Buyer\" "+
	"WHERE purchase.\"Buyer\" = StormMainObjectKey AND purchase.\"Status\" = \'submitted to the Bank\' ")]
// *** End programmer edit section *** (Buyer.Dostupnymi CustomAttributes) 
[ICSSoft.STORMNET.NotStored()]
public virtual decimal ДоступнаяСумма
{
	get
	{
		return this.cashedAvailableSum;
	}
	set
	{
		if (value != null)
		{
			this.cashedAvailableSum = value;
		}
	}
}

Warning: In the above example is omitted, if the value of datalow changes, then the cached value should be recalculated (for example, using SQL query)