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Some scenarios require that a value be stored in a database column in one form and written to and read from the database column in another form. Servoy supports this requirement with a feature called Column Conversion and it has two three applications, String Serialization, Blob Serialization and Global Method Conversion.

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Servoy supports object persistence using String Serialization, which involves the conversion of a runtime object into a string format, which can then persist in a database column. When the column is read from the database, the persistent string will be deserialized back into a runtime object. Because Servoy uses JavaScript as its scripting language, runtime objects will be serialized into standard JSON format.

//  Construct an object to capture some custom settings and write it directly to a Text column called 'custom_settings'
var obj = new Object();
obj.name = 'foobar';
obj.message = 'Hello World'; 

// at this point it is serialized into the string: "{name:'foobar',message:'Hello World'}"
custom_settings = obj;
databaseManager.saveData();

// ...read object properties at a later time...
application.output(custom_settings.message + 'My name is: ' + custom_settings.name);

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// For Example
my_data_provider.property = 'Foobar'; This will have no effect on the data provider

// Instead
var obj = my_data_provider; // read the data provider into a runtime object
obj.property = 'Foo Bar';   // Modify the Object's instance properties
my_data_provider = obj;     // And reassign it to the data providerdatabaseManager.saveData();

Blob Serialization

Servoy provides Blob Serialization for persisting an object as a Blob. This involves converting the runtime object into a Blob, which is then persisted in the database column. When retrieving the column data from the database, the Blob is deserialized back into a runtime object.

See code example at String Serialization.

Global Method Conversion

Servoy allows a database column to be bound to custom business logic, giving developers control over how a value is converted when it is written to, and read from the data provider.

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