fix diff changelog generating undesired changes (#679)

* fix: how a unique constraint is not unique!?

* fix: primary key backing index issues.

* fix: advanced validation for sequence fields managed by liquibase

* fix: allow allocation size of 50 to be the same as null

Author: filipelautert

src/main/java/liquibase/ext/hibernate/diff/ChangedPrimaryKeyChangeGenerator.java

@@ -0,0 +1,37 @@
+package liquibase.ext.hibernate.diff;
+
+import liquibase.change.Change;
+import liquibase.database.Database;
+import liquibase.diff.ObjectDifferences;
+import liquibase.diff.output.DiffOutputControl;
+import liquibase.diff.output.changelog.ChangeGeneratorChain;
+import liquibase.ext.hibernate.database.HibernateDatabase;
+import liquibase.structure.DatabaseObject;
+import liquibase.structure.core.PrimaryKey;
+
+/**
+ * Hibernate doesn't know about all the variations that occur with primary keys, especially backing index stuff.
+ * To prevent changing customized primary keys, we suppress this kind of changes from hibernate side.
+ */
+public class ChangedPrimaryKeyChangeGenerator extends liquibase.diff.output.changelog.core.ChangedPrimaryKeyChangeGenerator {
+
+    @Override
+    public int getPriority(Class<? extends DatabaseObject> objectType, Database database) {
+        if (PrimaryKey.class.isAssignableFrom(objectType)) {
+            return PRIORITY_ADDITIONAL;
+        }
+        return PRIORITY_NONE;
+    }
+
+    @Override
+    public Change[] fixChanged(DatabaseObject changedObject, ObjectDifferences differences, DiffOutputControl control, Database referenceDatabase, Database comparisonDatabase, ChangeGeneratorChain chain) {
+        if (referenceDatabase instanceof HibernateDatabase || comparisonDatabase instanceof HibernateDatabase) {
+            differences.removeDifference("unique");
+            if (!differences.hasDifferences()) {
+                return null;
+            }
+        }
+
+        return super.fixChanged(changedObject, differences, control, referenceDatabase, comparisonDatabase, chain);
+    }
+}

src/main/java/liquibase/ext/hibernate/diff/ChangedSequenceChangeGenerator.java

@@ -53,7 +53,39 @@ public Change[] fixChanged(DatabaseObject changedObject, ObjectDifferences diffe
                 .filter(differenceField ->  !HIBERNATE_SEQUENCE_FIELDS.contains(differenceField))
                 .collect(Collectors.toCollection(LinkedHashSet::new));
         ignoredDifferenceFields.forEach(differences::removeDifference);
+        this.advancedIgnoredDifferenceFields(differences, referenceDatabase, comparisonDatabase);
         return super.fixChanged(changedObject, differences, control, referenceDatabase, comparisonDatabase, chain);
     }
 
+
+    /**
+     * In some cases a value that was 1 can be null in the database, or the name field can be different only by case.
+     * This method removes these differences from the list of differences so we don't generate a change for them.
+     */
+    private void advancedIgnoredDifferenceFields(ObjectDifferences differences, Database referenceDatabase, Database comparisonDatabase) {
+        Set<String> ignoredDifferenceFields = new HashSet<>();
+        for (Difference difference : differences.getDifferences()) {
+            String field = difference.getField();
+            String refValue = difference.getReferenceValue() != null ? difference.getReferenceValue().toString() : null;
+            String comparedValue = difference.getComparedValue() != null ? difference.getComparedValue().toString() : null;
+
+            // if the name field case is different and the databases are case-insensitive, we can ignore the difference
+            boolean isNameField = field.equals("name");
+            boolean isCaseInsensitive = !referenceDatabase.isCaseSensitive() || !comparisonDatabase.isCaseSensitive();
+
+            // if the startValue or incrementBy fields are 1 and the other is null, we can ignore the difference
+            // Or 50, as it is the default value for hibernate for allocationSize:
+            // https://github.com/hibernate/hibernate-orm/blob/bda95dfbe75c68f5c1b77a2f21c403cbe08548a2/hibernate-core/src/main/java/org/hibernate/boot/model/IdentifierGeneratorDefinition.java#L252
+            boolean isStartOrIncrementField = field.equals("startValue") || field.equals("incrementBy");
+            boolean isOneOrFiftyAndNull = "1".equals(refValue) && comparedValue == null || refValue == null && "1".equals(comparedValue) ||
+                    "50".equals(refValue) && comparedValue == null || refValue == null && "50".equals(comparedValue);
+
+            if ((isNameField && isCaseInsensitive && refValue != null && refValue.equalsIgnoreCase(comparedValue)) ||
+                    (isStartOrIncrementField && isOneOrFiftyAndNull)) {
+                ignoredDifferenceFields.add(field);
+            }
+        }
+        ignoredDifferenceFields.forEach(differences::removeDifference);
+    }
+
 }

src/main/java/liquibase/ext/hibernate/diff/ChangedUniqueConstraintChangeGenerator.java

@@ -0,0 +1,37 @@
+package liquibase.ext.hibernate.diff;
+
+import liquibase.change.Change;
+import liquibase.database.Database;
+import liquibase.diff.ObjectDifferences;
+import liquibase.diff.output.DiffOutputControl;
+import liquibase.diff.output.changelog.ChangeGeneratorChain;
+import liquibase.ext.hibernate.database.HibernateDatabase;
+import liquibase.structure.DatabaseObject;
+import liquibase.structure.core.UniqueConstraint;
+
+/**
+ * Unique attribute for unique constraints backing index can have different values dependending on the database implementation,
+ * so we suppress all unique constraint changes based on unique constraints.
+
+ */
+public class ChangedUniqueConstraintChangeGenerator extends liquibase.diff.output.changelog.core.ChangedUniqueConstraintChangeGenerator {
+
+    @Override
+    public int getPriority(Class<? extends DatabaseObject> objectType, Database database) {
+        if (UniqueConstraint.class.isAssignableFrom(objectType)) {
+            return PRIORITY_ADDITIONAL;
+        }
+        return PRIORITY_NONE;
+    }
+
+    @Override
+    public Change[] fixChanged(DatabaseObject changedObject, ObjectDifferences differences, DiffOutputControl control, Database referenceDatabase, Database comparisonDatabase, ChangeGeneratorChain chain) {
+        if (referenceDatabase instanceof HibernateDatabase || comparisonDatabase instanceof HibernateDatabase) {
+            differences.removeDifference("unique");
+            if (!differences.hasDifferences()) {
+                return null;
+            }
+        }
+        return super.fixChanged(changedObject, differences, control, referenceDatabase, comparisonDatabase, chain);
+    }
+}

src/main/java/liquibase/ext/hibernate/snapshot/UniqueConstraintSnapshotGenerator.java

@@ -15,7 +15,6 @@
 import java.math.BigInteger;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
-import java.util.Iterator;
 
 public class UniqueConstraintSnapshotGenerator extends HibernateSnapshotGenerator {
 
@@ -54,7 +53,7 @@ protected void addTo(DatabaseObject foundObject, DatabaseSnapshot snapshot) thro
                 Index index = getBackingIndex(uniqueConstraint, hibernateTable, snapshot);
                 uniqueConstraint.setBackingIndex(index);
 
-                Scope.getCurrentScope().getLog(getClass()).info("Found unique constraint " + uniqueConstraint.toString());
+                Scope.getCurrentScope().getLog(getClass()).info("Found unique constraint " + uniqueConstraint);
                 table.getUniqueConstraints().add(uniqueConstraint);
             }
             for (var column : hibernateTable.getColumns()) {
@@ -68,7 +67,7 @@ protected void addTo(DatabaseObject foundObject, DatabaseSnapshot snapshot) thro
                     }
                     uniqueConstraint.addColumn(0, new Column(column.getName()).setRelation(table));
                     uniqueConstraint.setName(name);
-                    Scope.getCurrentScope().getLog(getClass()).info("Found unique constraint " + uniqueConstraint.toString());
+                    Scope.getCurrentScope().getLog(getClass()).info("Found unique constraint " + uniqueConstraint);
                     table.getUniqueConstraints().add(uniqueConstraint);
 
                     Index index = getBackingIndex(uniqueConstraint, hibernateTable, snapshot);

src/main/resources/META-INF/services/liquibase.diff.output.changelog.ChangeGenerator

@@ -1,5 +1,7 @@
 liquibase.ext.hibernate.diff.ChangedColumnChangeGenerator
 liquibase.ext.hibernate.diff.ChangedForeignKeyChangeGenerator
+liquibase.ext.hibernate.diff.ChangedPrimaryKeyChangeGenerator
 liquibase.ext.hibernate.diff.ChangedSequenceChangeGenerator
+liquibase.ext.hibernate.diff.ChangedUniqueConstraintChangeGenerator
 liquibase.ext.hibernate.diff.MissingSequenceChangeGenerator
 liquibase.ext.hibernate.diff.UnexpectedIndexChangeGenerator