DATACASS-522 - Allow for conditionally dropping a table iff the table exists.

spring-data-cassandra/src/main/java/org/springframework/data/cassandra/core/CassandraAdminOperations.java

@@ -39,7 +39,7 @@ public interface CassandraAdminOperations extends CassandraOperations {
 	 * doesn't exist, parameter {@code ifNotExists} is ignored, the table is created and {@literal true} is returned.
 	 *
 	 * @param ifNotExists If true, will only create the table if it doesn't exist, else the create operation will be
-	 *          ignored and the method will return {@literal false}.
+	 *          ignored.
 	 * @param tableName The name of the table.
 	 * @param entityClass The class whose fields determine the columns created.
 	 * @param optionsByName Table options, given by the string option name and the appropriate option value.
@@ -54,6 +54,15 @@ public interface CassandraAdminOperations extends CassandraOperations {
 	 */
 	void dropTable(CqlIdentifier tableName);
 
+	/**
+	 * Drops the named table.
+	 *
+	 * @param ifExists If true, will only drop the table if it exists, else the create operation will be ignored.
+	 * @param tableName The name of the table.
+	 * @since 2.1
+	 */
+	void dropTable(boolean ifExists, CqlIdentifier tableName);
+
 	/**
 	 * Lookup {@link TableMetadata}.
 	 *

spring-data-cassandra/src/main/java/org/springframework/data/cassandra/core/CassandraAdminTemplate.java

@@ -90,7 +90,13 @@ public class CassandraAdminTemplate extends CassandraTemplate implements Cassand
 	 */
 	@Override
 	public void dropTable(CqlIdentifier tableName) {
-		getCqlOperations().execute(DropTableCqlGenerator.toCql(DropTableSpecification.dropTable(tableName)));
+		dropTable(false, tableName);
+	}
+
+	@Override
+	public void dropTable(boolean ifExists, CqlIdentifier tableName) {
+		getCqlOperations()
+				.execute(DropTableCqlGenerator.toCql(DropTableSpecification.dropTable(tableName).ifExists(ifExists)));
 	}
 
 	/*

spring-data-cassandra/src/main/java/org/springframework/data/cassandra/core/cql/generator/DropTableCqlGenerator.java

@@ -21,6 +21,7 @@ import org.springframework.data.cassandra.core.cql.keyspace.DropTableSpecificati
  * CQL generator for generating a {@code DROP TABLE} statement.
  *
  * @author Matthew T. Adams
+ * @author Mark Paluch
  */
 public class DropTableCqlGenerator extends TableNameCqlGenerator<DropTableSpecification> {
 
@@ -35,7 +36,7 @@ public class DropTableCqlGenerator extends TableNameCqlGenerator<DropTableSpecif
 	@Override
 	public StringBuilder toCql(StringBuilder cql) {
 		return cql.append("DROP TABLE ")
-				// .append(spec().getIfExists() ? "IF EXISTS " : "")
+				.append(spec().getIfExists() ? "IF EXISTS " : "")
 				.append(spec().getName()).append(";");
 	}
 }

spring-data-cassandra/src/main/java/org/springframework/data/cassandra/core/cql/keyspace/DropTableSpecification.java

@@ -25,6 +25,8 @@ import org.springframework.data.cassandra.core.cql.CqlIdentifier;
  */
 public class DropTableSpecification extends TableNameSpecification {
 
+	private boolean ifExists = false;
+
 	private DropTableSpecification(CqlIdentifier name) {
 		super(name);
 	}
@@ -50,4 +52,31 @@ public class DropTableSpecification extends TableNameSpecification {
 	public static DropTableSpecification dropTable(CqlIdentifier tableName) {
 		return new DropTableSpecification(tableName);
 	}
+
+	/**
+	 * Causes the inclusion of an {@code IF EXISTS} clause.
+	 *
+	 * @return this
+	 * @since 2.1
+	 */
+	public DropTableSpecification ifExists() {
+		return ifExists(true);
+	}
+
+	/**
+	 * Toggles the inclusion of an {@code IF EXISTS} clause.
+	 *
+	 * @return this
+	 * @since 2.1
+	 */
+	public DropTableSpecification ifExists(boolean ifExists) {
+
+		this.ifExists = ifExists;
+
+		return this;
+	}
+
+	public boolean getIfExists() {
+		return ifExists;
+	}
 }