Package com.github.collinalpert.java2db.queries

Class SingleEntityQuery<E extends BaseEntity>

java.lang.Object

com.github.collinalpert.java2db.queries.SingleEntityQuery<E>

All Implemented Interfaces:

SingleQueryable<E>

Direct Known Subclasses:

AsyncSingleEntityQuery, EntityQuery

public class SingleEntityQuery<E extends BaseEntity>
extends Object
implements SingleQueryable<E>

Author:

Collin Alpert

Field Summary

Fields

Modifier and Type	Field	Description
protected Map<String,String>	aliases
protected Mappable<E>	mapper
protected static TableModule	tableModule
protected Class<E>	type

Constructor Summary

Constructors

Constructor	Description
SingleEntityQuery(Class<E> type)

Method Summary

Modifier and Type	Method	Description
protected void	buildWhereClause(StringBuilder builder, String tableName)	Builds the WHERE clause in a select statement.
Optional<E>	first()	Gets the first record of a result.
String	getQuery()	Builds the query from the set query options.
String	getTableName()	Gets the table name which this query targets.
SingleEntityQuery<E>	orWhere(com.github.collinalpert.lambda2sql.functions.SqlPredicate<E> predicate)	Sets or appends an OR WHERE clause to the DQL statement.
<R> SingleQueryable<R>	project(com.github.collinalpert.lambda2sql.functions.SqlFunction<E,R> projection)	Selects only a single column from a table.
SingleEntityQuery<E>	where(com.github.collinalpert.lambda2sql.functions.SqlPredicate<E> predicate)	Sets or appends a WHERE clause for the DQL statement.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

tableModule

protected static final TableModule tableModule

type

protected final Class<E extends BaseEntity> type

mapper

protected final Mappable<E extends BaseEntity> mapper

aliases

protected Map<String,String> aliases

Constructor Detail

SingleEntityQuery

public SingleEntityQuery(Class<E> type)

Method Detail

where

public SingleEntityQuery<E> where(com.github.collinalpert.lambda2sql.functions.SqlPredicate<E> predicate)

Sets or appends a WHERE clause for the DQL statement.

Parameters:

predicate - The predicate describing the WHERE clause.

Returns:

This EntityQuery object, now with an (appended) WHERE clause.

orWhere

public SingleEntityQuery<E> orWhere(com.github.collinalpert.lambda2sql.functions.SqlPredicate<E> predicate)

Sets or appends an OR WHERE clause to the DQL statement.

Parameters:

predicate - The predicate describing the OR WHERE clause.

Returns:

This EntityQuery object, now with an (appended) OR WHERE clause.

project

public <R> SingleQueryable<R> project(com.github.collinalpert.lambda2sql.functions.SqlFunction<E,R> projection)

Selects only a single column from a table. This is meant if you don't want to fetch an entire entity from the database.

Type Parameters:

R - The type of the column you want to retrieve.

Parameters:

projection - The column to project to.

Returns:

A queryable containing the projection.

first

public Optional<E> first()

Gets the first record of a result. This method should be used when only one record is expected, i.e. when filtering by a unique identifier such as an id.

Specified by:

first in interface SingleQueryable<E extends BaseEntity>

Returns:

The first row as an entity wrapped in an Optional if there is at least one row. Otherwise Optional.empty() is returned.

getQuery

public String getQuery()

Builds the query from the set query options.

Specified by:

getQuery in interface SingleQueryable<E extends BaseEntity>

Returns:

The DQL statement for getting data from the database.

buildWhereClause

protected void buildWhereClause(StringBuilder builder,
                                String tableName)

Builds the WHERE clause in a select statement.

Parameters:

builder - The StringBuilder to append the clause to.

tableName - The name of the table the where clause will affect.

getTableName

public String getTableName()

Gets the table name which this query targets.

Returns:

The table name which this query targets.