JDOQL : Methods

When writing the "filter" for a JDOQL Query you can make use of some methods on the various Java types. The range of methods included as standard in JDOQL is not as flexible as with the true Java types, but the ones that are available are typically of much use.


String Methods

Method Description

startsWith(String)

Returns if the string starts with the passed string

startsWith(String, int)

Returns if the string starts with the passed string, after the specified position

endsWith(String)

Returns if the string ends with the passed string

indexOf(String)

Returns the first position of the passed string

indexOf(String, int)

Returns the position of the passed string, after the passed position

substring(int)

Returns the substring starting from the passed position

substring(int, int)

Returns the substring between the passed positions

toLowerCase()

Returns the string in lowercase

toUpperCase()

Returns the string in UPPERCASE

matches(String pattern)

Returns whether string matches the passed expression. The pattern argument follows the rules of java.lang.String.matches method.

trim()

Returns the string with leading/trailing spaces trimmed

length()

Returns the length of the string

charAt(int)

Returns the character at the specified position of the string

Here’s an example using a Product class, looking for objects whose abbreviation is the beginning of a trade name. The trade name is provided as parameter.

Declarative JDOQL :
Query query = pm.newQuery(mydomain.Product.class);
query.setFilter(":tradeName.startsWith(this.abbreviation)");
List results = (List)query.execute("Workbook Advanced");

Single-String JDOQL :
Query query = pm.newQuery(
    "SELECT FROM mydomain.Product " +
    "WHERE :tradeName.startsWith(this.abbreviation)");
List results = (List)query.execute("Workbook Advanced");


Here’s another example, demonstrating the "matches" method. Consult the javadocs for Java regular expressions for the syntax of the matches input.

Declarative JDOQL :
Query query = pm.newQuery(mydomain.Product.class);
query.setFilter("this.abbreviation.matches(\"a*b\")");
List results = (List)query.execute();

Single-String JDOQL :
Query query = pm.newQuery(
    "SELECT FROM mydomain.Product " +
    "WHERE this.abbreviation.matches(\"a*b\")");
List results = (List)query.execute();


Collection Methods

Method Description

isEmpty()

Returns whether the collection is empty

contains(value)

Returns whether the collection contains the passed element

size()

Returns the number of elements in the collection

Here’s an example demonstrating use of contains(). We have an Inventory class that has a Collection of Product objects, and we want to find the Inventory objects with 2 particular Products in it. Here we make use of a variable (prd to represent the Product being contained

Declarative JDOQL :
Query query = pm.newQuery(mydomain.Inventory.class);
query.setFilter("products.contains(prd) && (prd.name==\"product 1\" || prd.name==\"product 2\")");
List results = (List)query.execute();

Single-String JDOQL:
Query query = pm.newQuery(
    "SELECT FROM mydomain.Inventory EXCLUDE SUBCLASSES " +
    "WHERE products.contains(prd) && (prd.name==\"product 1\" || prd.name==\"product 2\")");
List results = (List)query.execute();


List Methods

Method Description

get(position)

Returns the element at that position in the List (JDO3.1)


Map Methods

Method Description

isEmpty()

Returns whether the map is empty

containsKey(key)

Returns whether the map contains the passed key

containsValue(value)

Returns whether the map contains the passed value

get(key)

Returns the value from the map with the passed key

size()

Returns the number of entries in the map

Here’s an example using a Product class as a value in a Map. Our example represents an organisation that has several Inventories of products. Each Inventory of products is stored using a Map, keyed by the Product name. The query searches for all Inventories that contain a product with the name "product 1".

Declarative JDOQL :
Query query = pm.newQuery(mydomain.Inventory.class, "products.containsKey(\"product 1\")");
List results = (List)query.execute();

Single-String JDOQL :
Query query = pm.newQuery(
    "SELECT FROM mydomain.Inventory EXCLUDE SUBCLASSES " +
    "WHERE products.containsKey(\"product 1\")");
List results = (List)query.execute();


Temporal Methods

Method Description

getDay()

Returns the day of the month

getMonth()

Returns the month of the year

getYear()

Returns the year

getHour()

Returns the hour

getMinute()

Returns the minute

getSecond()

Returns the second


Enum Methods

Method Description

ordinal()

Returns the ordinal of the enum

toString()

Returns the string form of the enum


Other Methods

Method Description

Math.abs(number)

Returns the absolute value of the passed number

Math.sqrt(number)

Returns the square root of the passed number

Math.cos(number)

Returns the cosine of the passed number

Math.sin(number)

Returns the sine of the passed number

Math.tan(number)

Returns the tangent of the passed number

JDOHelper.getObjectId(object)

Returns the object identity of the passed persistent object

JDOHelper.getVersion(object)

Returns the version of the passed persistent object