The Ed-Fi ODS SQL Server data store allows for the configuration of Cascading Updates on entities. Cascading Update specifies that if an update is made to a key value in a data row where the key value is referenced by foreign keys, then all existing foreign key values are updated to the new key value.1
The following ODS / API resources are already configured for Cascading Updates in the as-shipped solution:
- Class Period
- Student School Association
- Student Section Association
However, some implementers may find it useful to enable Cascading Updates on additional resources including core resources and extension resources.
Changes are not supported in Binary installation
In order to make changes to Cascading Updates on a core resource, installation from source code is required. When changes are made, be aware that the changes could be lost when upgrading to a newer version of the API and care must be taken to reapply the changes.
Configure Cascading Updates on an Ed-Fi Core resource
Cascading key updates are configured in MetaEd by 'allow primary key updates' language construct. However since the core model cannot be updated, we provide steps to modify generated artifacts to enable cascading key updates on core resources that are not preconfigured for cascading updates.
- Update the Api Model
- Locate the ApiModel.json file located in <source code root directory>Ed-Fi-ODS\Application\EdFi.Ods.Standard\Artifacts\Metadata
- Find the model you want to enable cascading updates on
- Within the identifiers array, find the primary key identifier (isPrimary flag will be true)
- Update the isUpdatable property to true
- Run the code generation steps outlined in the Getting Started Guide (i.e., from a PowerShell prompt run
Initialize-PowershellForDevelopment.psscript, followed by the
- Update Foreign Key Constraints for all dependencies
- SQL Server - Locate the 0030-ForeignKeys.sql file located in <source code root directory>\Ed-Fi-ODS\Application\EdFi.Ods.Standard\Artifacts\MsSql\Structure\Ods
- PostgreSQL- Locate the 0030-ForeignKeys.sql file located in <source code root directory>\Ed-Fi-ODS\Application\EdFi.Ods.Standard\Artifacts\PgSql\Structure\Ods
- Identify all dependent resource foreign key constraints (Search for "REFERENCES [edfi].[<Resource_Name>]")
- Copy each of the the ALTER TABLE scripts to a separate text document
- Add a ALTER TABLE <TableName> DROP CONSTRAINT <ConstraintName> to the line before each of the copied ALTER TABLE Scripts
- Add ON UPDATE CASCADE1 to each of the copied ALTER TABLE scripts
- Execute all of these SQL Scripts on the target ODS
Here is an example scenario to demonstrate the steps needed to update a Core resource. We will use the Account core resource as an example of a resource to enable cascading updates on. Note that the default behavior of the Account resource is not configured for cascading natural key updates via the PUT method.
We can modify this behavior by updating the APIModel.json file. Locate the Account resource you want to update. Then, within the identifiers array, find the primary key identifier and update the isUpdatable property to true.
Run the code generation steps outlined in the Getting Started Guide (i.e., from a PowerShell prompt run
Initialize-PowershellForDevelopment.ps script, followed by the
initdev command). At this point, the API would allow for natural key cascading updates, but database is not set to support the cascading updates yet. We need to update the foreign key constraints that dependencies of Account have on the target ODS.
Configure Cascading Updates on an Ed-Fi Extension resource
For configuring cascading key updates on the extension resource, simply add the 'allow primary key updates' language construct to the .metaed file in your extension project. For more details on creating Ed-Fi Extensions, see here.
1 For more details on Table Cascading Updates, see here.