com.softwareag.eda.estore.query.api.builder

Class QueryBuilder

java.lang.Object

com.softwareag.eda.estore.query.api.builder.QueryBuilder

public final class QueryBuilder
extends java.lang.Object

The QueryBuilder provides a simple DSL for creating queries for use with the Common Query API. In the Common Query API a Query reference is obtained from the QuerySession which is passed the query statement as a String. As the queries become more complex building up the query string becomes cumbersome like working with large blocks of SQL. The builder lets developers construct the query through a set of chained Java methods. Methods are provided for each area of the query such as setting the select, where clause, group by clause and order by clauses. Once the builder has been configured the build method should be called to generate the string representation of the query. This string can then be passed to the QuerySession when creating a new Query reference.

Constructor Summary

Constructors

Constructor and Description
QueryBuilder()

Method Summary

Modifier and Type	Method and Description
QueryBuilder	addAggregate(Aggregate aggregate) Adds an Aggregate function to this queries select expression.
QueryBuilder	addSelectProperty(java.lang.String property) Adds an Event Types property value to this queries select expression.
java.lang.String	build() The "build" method is used to evaluate the builders state and return a string representation of the query suitable for use when creating Query instances through the QuerySession.
QueryBuilder	setEventNamespace(java.lang.String eventNamespace) Sets the namespace containing the EventType for use in this queries "in" clause.
QueryBuilder	setEventType(java.lang.String eventType) Sets the name of the Event Type in this queries "from" clause.
QueryBuilder	setGroupBy(GroupBy groupBy) Sets the group by clause for this query.
QueryBuilder	setOrderBy(OrderBy orderBy) Sets the order by clause for this query.
QueryBuilder	setWhereClause(ExpressionBuilder expression) Sets the where clause to be used in this query.

Methods inherited from class java.lang.Object

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

Constructor Detail

QueryBuilder

public QueryBuilder()

Method Detail

setEventType

public QueryBuilder setEventType(java.lang.String eventType)

Sets the name of the Event Type in this queries "from" clause.

Parameters:

eventType - The value of the Event Type to be used in this queries from clause.

Returns:

A reference to this query builder instance to enable method chaining

setEventNamespace

public QueryBuilder setEventNamespace(java.lang.String eventNamespace)

Sets the namespace containing the EventType for use in this queries "in" clause.

Parameters:

eventNamespace - The namespace that contains the specified event type.

Returns:

A reference to this query builder instance to enable method chaining

addSelectProperty

public QueryBuilder addSelectProperty(java.lang.String property)

Adds an Event Types property value to this queries select expression. If a queries select expression contains one or more event properties only those properties are returned from the query. This allows developers to work with a sub-set of the Events properties.

Parameters:

property - The Event property to be returned in the query result.

Returns:

A reference to this query builder instance to enable method chaining

addAggregate

public QueryBuilder addAggregate(Aggregate aggregate)

Adds an Aggregate function to this queries select expression. A select expression can contain Event properties and/or Aggregate functions. When combined each result can be used in the OrderBy and GroupBy expressions. The Aggregate class provides static "factory" methods for creating expressions such as average, count and sum.

Parameters:

aggregate - The aggregate operation to be added to the query.

Returns:

A reference to this query builder instance to enable method chaining

setWhereClause

public QueryBuilder setWhereClause(ExpressionBuilder expression)

Sets the where clause to be used in this query. The expression for the where clause is build up and configured using the ExpressionBuilder. The ExpressionBuilder provides all of the methods needed to construct simple and complex search expressions.

Parameters:

expression - An ExpressionBuilder reference used to configure the search expression.

Returns:

A reference to this query builder instance to enable method chaining

setOrderBy

public QueryBuilder setOrderBy(OrderBy orderBy)

Sets the order by clause for this query. The OrderBy class provides a mini-DSL to create an OrderBy instance and methods to add one or more Event properties and the sort critera for each. If this method is called but the OrderBy reference contains no properties and error will occur. In the future validations will be added and performed during the "build" operation.

Parameters:

orderBy - A OrderBy reference containing the Event properties and sort options.

Returns:

A reference to this query builder instance to enable method chaining

setGroupBy

public QueryBuilder setGroupBy(GroupBy groupBy)

Sets the group by clause for this query. The GroupBy class provides a mini-DSL to create a GroupBy instance and methods to add one or more Event properties that specific the desired grouping for the results. If this method is called but the GroupBy reference contains no properties and error will occur. In addition if no Aggregate operations have been set in the select expression and a group by is specified an error will occur. In the future validations will be added and performed during the "build" operation.

Parameters:

groupBy - A configured group by reference.

Returns:

A reference to this query builder instance to enable method chaining

build

public java.lang.String build()
                       throws QueryBuilderException

The "build" method is used to evaluate the builders state and return a string representation of the query suitable for use when creating Query instances through the QuerySession.

Returns:

A string representation of this builders query in the common syntax.

Throws:

QueryBuilderException - if the query string can't be constructed from the current properties.