Retaining table data after publishing

When developing an extension, you debug several times using the F5 shortcut key, and you also test your app by adding some sample data every time. To simplify the extension development process in Business Central, you can synchronize the sample data specified in the extension when you do subsequent publishing from Visual Studio Code.

How data synchronization works

The data synchronization between each publish is controlled by the schemaUpdateMode setting, which is specified in the launch.json file. This setting consists of three options; Synchronize, Recreate, and ForceSync.

The default value for schemaUpdateMode is set to the Synchronize mode, which means that every time you publish an extension to the development server, the data you entered previously stays. If you do not want to synchronize the sample data with each publish, you can change the schemaUpdateMode setting from Synchronize to, for example, Recreate with the syntax shown in the example below.

     "type": "al",
     "request": "launch",
     "name": "your own server",
     "server": "https://localhost",
     "serverInstance": "Nav",
     "authentcation": "UserPassword", 
     "startupobjectId": 22,
     "schemaUpdateMode": "Recreate" 

Recreate mode

When you set the schema update mode to Recreate, all the tables and table extensions are recreated at every publish, which means that all the data in those tables are lost. This means that you will get empty records when you publish your extension.

ForceSync mode

ForceSync is similar to the existing Synchronize schema update mode, but contains more freedom to make schema changes while retaining data. To enable this mode, set schemaUpdateMode to "ForceSync"and then set the "version" parameter in the app.json file to a fixed number. Data will be preserved in almost all cases with the exception of changing the main table's primary key, in which case the data from the extension tables will be lost. Field renames are allowed and supported in this mode, but the data can only be preserved if you maintain the same ID for the field. If you change both the name and the ID of the field then the data will be lost.


This schema update mode is only meant for testing and development and should never be used in production.

In addition to the launch.json file setting, the ForceSync switch is available through the PowerShell cmdlet Sync-NavApp –Mode ForceSync.

Things to be aware of

Synchronize is the default schema update mode for syncing the database and the extension. There are some key factors to consider when you work with the Synchronize mode.

  • After publishing, the field data and the primary key information synchronizes with all the tables and the table extensions. This means that you can do additions easily, but not deletions. Breaking changes are never supported in synchronize mode. For example, you can add a field and sync that with the extension just by pressing the F5 shortcut key, but if a field is removed then the table data cannot be synchronized. If you, during development, for example, discover that you no longer want field X, and you then mark field X as obsolete, you may still want to write an upgrade codeunit to move the data from the obsolete field to a new field Y that you introduce. Later, the obsoleted field will not be available. But if you do not want the data, you can choose to use the Recreate mode instead.

  • When you make changes to the data types, you can only enlarge the unit size, and not decrease the unit size. For example, you can set a text type from Code[20] to Code[50] or Text[32] to Text[87], and you cannot set a text type from Code[50] to Code[30] or Text[87] to Text[40].

  • For field data types, however, changing the length is not allowed. If you, for example, change version 1.0 of the field(50100; MyField; Text[50]) to field(50100; MyField; Text[150]) in version 2.0 it is considered a breaking change. For more information, see AppSourceCop Rule AS0086.

  • Making major table structural changes could lead to compilation errors. For example, if you want to update a primary key. In this case, the table data cannot be synchronized, and if you want to publish the extension, you must change the schemaUpdateMode to Recreate. Likewise, changing the DataPerCompany from true to false and from false to true is a schema-breaking change, and therefore not allowed because it changes the number of tables per company.

  • For extensions built on Business Central Spring 2019 or earlier, if a table field has the SqlDataType set to a value other than Varchar (which is the default), you must delete the SqlDataType property on the field, otherwise, you will will not be able to successfully synchronize the extension.

    If the SqlDataType property is still needed, you will have to create a new table in the extension that has the same definition as the original table, and write upgrade code that migrates the data from the original table to the new table. For more information, see Writing upgrade code.

    Alternatively, if this is a development scenario, you can synchronize the extension using the ForceSync or Recreate mode.

See Also

AL Development Environment
Upgrading Extensions