leap.orm.query.QueryBase Maven / Gradle / Ivy
/*
* Copyright 2019 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package leap.orm.query;
import leap.core.exception.EmptyRecordsException;
import leap.core.exception.TooManyRecordsException;
import leap.core.value.Scalar;
import leap.core.value.Scalars;
import java.util.List;
public interface QueryBase {
/**
* Returns true if the result has records, or returns false if no records.
*/
default boolean exists() {
return firstOrNull() != null;
}
/**
* Executes this query and return the query result.
*/
QueryResult result();
/**
* Executes this query and return the first row.
*
* @throwsh {@link EmptyRecordsException} if no result returned.
*
* @see QueryResult#first()
*/
T first() throws EmptyRecordsException;
/**
* Executes this query and return the first row.
*
*
* Returns null if no result returned.
*
* @see QueryResult#firstOrNull()
*/
T firstOrNull();
/**
* Executes this query and return the first row.
*
* @throws EmptyRecordsException if no result returned.
* @throws TooManyRecordsException if two or more rows returned.
*
* @see QueryResult#single()
*/
T single() throws EmptyRecordsException,TooManyRecordsException;
/**
* Executes this query and return the first row.
*
*
* Returns null if no result returned.
*
* @throws TooManyRecordsException if two or more rows returned.
*
* @see QueryResult#singleOrNull()
*/
T singleOrNull() throws TooManyRecordsException;
/**
* Executes this query and return all the rows as a immutable {@link List} object.
*
*
* Returns a empty immutable {@link List} if no result returned.
*
* @see QueryResult#list()
*/
List list();
/**
* Returns the {@link Scalar} value in this query result.
*
* @throws EmptyRecordsException if no records.
* @throws TooManyRecordsException if two or more records returned.
*/
Scalar scalar() throws EmptyRecordsException, TooManyRecordsException;
/**
* Returns the {@link Scalar} value in this query result or null if no records returned.
*
* @throws TooManyRecordsException if two or more records returned.
*/
Scalar scalarOrNull() throws TooManyRecordsException;
/**
* Returns the scalar value or null if n o records returned.
*
* @throws TooManyRecordsException if two or more records returned.
*/
default T scalarValueOrNull() throws TooManyRecordsException {
Scalar scalar = scalarOrNull();
return null == scalar ? null : (T)scalar.get();
}
/**
* Returns the scalar value or null if n o records returned.
*
* @throws TooManyRecordsException if two or more records returned.
*/
default T scalarValueOrNull(Class type) throws TooManyRecordsException {
Scalar scalar = scalarOrNull();
return null == scalar ? null : scalar.get(type);
}
/**
* Returns all the scalar values of the first column in this query result.
*/
Scalars scalars();
}