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https://issues.apache.org/jira/browse/CAY-1395?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrus Adamchik updated CAY-1395:
---------------------------------
Fix Version/s: (was: 3.1)
Undefined future
> createSetAllowNullToDb() can lead to data corruption, returns incorrect SQL
> statement to createSql()
> -----------------------------------------------------------------------------------------------------
>
> Key: CAY-1395
> URL: https://issues.apache.org/jira/browse/CAY-1395
> Project: Cayenne
> Issue Type: Bug
> Components: Core Library
> Affects Versions: 3.0RC2
> Reporter: Øyvind Harboe
> Fix For: 3.0.3, Undefined future
>
>
> SQLServerManagerFactory.createSetAllowNullToDb() can cause data corruption.
> The problem is that it assumes that the column passed in to the constructor
> contains the properties read from the database.
> Consider a text field where the column passed to the constructor is *shorter*
> than what's currently used in the database.
> In the use of a a merger context one could decide *only* to try to change the
> allow null property and leave the length of the text field alone. In this
> case changing the allow null property will truncate the length of the text
> field as a side effect.
> Consider the MS SQL server syntax to set the NOT NULL (do not allow null)
> syntax:
> ALTER TABLE consequence ALTER COLUMN cons_id int NOT NULL
> Here the type of the field must preceed the NOT NULL and hence you have to
> *know* the type in the database to modify the allow null property while
> leaving the type alone...
> SetNotNullToDb() does not suffer from this problem as it changes *only* the
> allow null property.
> @Override
> public List<String> createSql(DbAdapter adapter) {
> StringBuilder sqlBuffer = new StringBuilder();
> QuotingStrategy context = adapter.getQuotingStrategy(getEntity()
> .getDataMap()
> .isQuotingSQLIdentifiers());
> sqlBuffer.append("ALTER TABLE ");
> sqlBuffer.append(context.quoteFullyQualifiedName(getEntity()));
> sqlBuffer.append(" ALTER COLUMN ");
> sqlBuffer.append(context.quoteString(getColumn().getName()));
> sqlBuffer.append(" SET NOT NULL");
> return Collections.singletonList(sqlBuffer.toString());
> }
> I've hacked up SQLMergerFactory locally and it appears to work fine in my
> particular case:
> return new SetAllowNullToDb(entity, column) {
> @Override
> public List<String> createSql(DbAdapter adapter) {
> StringBuffer sqlBuffer = new StringBuffer();
> QuotingStrategy context =
> adapter.getQuotingStrategy(getEntity()
> .getDataMap()
> .isQuotingSQLIdentifiers());
> sqlBuffer.append("ALTER TABLE ");
>
> sqlBuffer.append(context.quoteFullyQualifiedName(getEntity()));
> sqlBuffer.append(" ALTER COLUMN ");
> /* Kludge!!!! how should this be handled really??? */
> column.setMandatory(false);
> adapter.createTableAppendColumn(sqlBuffer, column);
> return Collections.singletonList(sqlBuffer.toString());
> }
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