Building Content Queries with Expressions

• Queries are case sensitive.
• Queries can be simple, one-clause queries, or they can be more complex, multi-clause queries. In complex queries, parentheses control the order of evaluation for multiple query clauses, and clauses are evaluated using and (&&) and or (||) logic.
• In placeholders, only one content item can be displayed at a time. If a placeholder is being used to run queries from campaigns as well as its own default queries, many possible queries can be run, but only one query at a time is run, which is determined by the placeholder's weighting system. Once a query is run, the query can return multiple content items, but only one of the retrieved content items is displayed in the placeholder.

• With your development server running, create a test placeholder or content selector in WebLogic Workshop and construct queries for it on the Advanced tab of the Content Search window. The retrieved content is displayed in WebLogic Workshop's Content Preview window. If you use the userProperty() format to retrieve values for your query, you must enter a user name in the Preview User field of the Content Preview window to retrieve the values for that user and display the retrieved content items.
• The Advanced query window provides code coloring to highlight context errors in your queries.
• You can reuse existing queries by pasting them into the Advanced query window.

Properties

There are two types of properties for content, and you can use both in queries: user-defined content properties and explicit (system) content properties.

User-defined content properties are stored in sets called "types," which are defined in the WebLogic Administration Portal. For example, you can create a type called "Book" and add properties like "title", "author", "pub_date", and "isbn".

Explicit content properties are automatically associated with all content items and are automatically assigned values for a content item when that content item is added to the content repository. These properties, which are also listed in the com.bea.content.expression.Search class, are:

In a query, you can specify property names by themselves without quotes.

For example: title <comparator> <value>.

However, if a property name contains spaces, double quotes, or dashes, you must enclose the property name within a toProperty() format.

For example: toProperty('Favorite Author') <comparator> <value>.

The query looks for the property name in all content types and returns any content item with that property value (if the content item meets the conditions of the query). However, you can also isolate a property within a specific type. For example, if you have a type "books" and a type "articles" that both contain a "title" property, you can retrieve content items with a specific "title" from within only the "book" type using the cm_objectClass property.

For example: title likeignorecase '*Adventure' && cm_objectClass = 'books'

Comparators

Comparators provide the logic that compares a query's property to the value you enter. If a content item meets the conditions of the query, the content item is returned. Following are the comparators you can use in your queries.

Values

Values represent the content you want the query to return. By supplying values to a query, you're telling the query which content to retrieve (or ignore) based on the values stored on the content items.

For example, if you have a content type called "book" with a property called "title", all content items you associate with the "book" type have a "title" field. Each "title" value is unique, so in a query, you can enter the unique value you want, resulting in the query retrieving a specific content item (or ignoring the content item, depending on the comparator you use).

You can enter values in two ways: hard code them in the queries or get them from user profiles and other types of property sets (session and request).

With hard-coded values, you get predictability with your queries, because you can pinpoint the specific content you want to retrieve.

When you populate values from user profile, session, or request property sets, the value in each specified user profile/session/request property is inserted programmatically into the query, letting you create personalized queries based on the current user's preferences or the current session or request. For example, in a query where a content property is "author", you can get the value of the user's "FavoriteAuthor" profile property to supply the value for the query, letting the query retrieve content associated with the user's favorite author.

Following are guidelines for building values in queries:

• Enclose String literal values in single quotes. For example: 'pending'.
• To supply a single or double quote, use a backslash for the quoting character (unicode characters are not supported). For example, if a book title is stored with double quotes, such as "The Crazy Adventure", enter the value like this: '\"The Crazy Adventure\"'. If the title is stored with single quotes, enter the value like this: title = '\'The Crazy Adventure\''
• Unicode (such as "\u6565"), octal (such as "\7", "\65", "\377"), and standard Java escape sequences (such as "\n", "\r", "\b") are allowed in the String literals.
• Boolean literals are either the true or false keyword (lowercase, without quotes).
• Number literals are Java form (scientific notation is supported).
• Date/time literals are presented in toDate('formatStr', 'dateStr') format, where formatStr is the date/time format you want to use (such as 'MM/dd/yyyy') and dateStr is the actual date/time you enter (such as '01/01/2006').
  
  The formatStr must be a valid java.text.SimpleDateFormat String. If you omit the formatStr, toDate() expects the date/time you enter to be in the following format: 'MM/dd/yyyy HH:mm:ss z' (where z is the time zone, such as MDT). For example: toDate('12/01/2004 06:00:00 MDT').
  
  To specify date values only, enter the format you want for the formatStr. For example, for a date value only, specify toDate('MM/dd/yyyy', '12/01/2004'). You can also specify the month and year only, such as 'MM-yyyy'.
  
  Use the now keyword to specify the time at which the expression is being parsed at run time.
• To supply query values from user, request, or session properties, use the following format: <type>Property(<propertyset>, <propertyname>), where type is user, request, or session. For example: userProperty('userpreferences', 'FavoriteAuthor').

Guidelines for Complex Queries

You can combine multiple independent query clauses, tying them together with and (&&) and or (||) logic and controlling the order of evaluation with parentheses the way you would with algebraic expressions. This lets you create more complex queries. You can also include "not" logic (!) in complex queries by using the exclamation point in front of a parenthetical grouping. The sample queries in this topic provide examples of complex queries. There is also an example that uses "not" logic.

Sample Queries

The following figure shows the properties set on a graphic stored in BEA's Virtual Content Repository.

The example queries following the figure are written using properties in this sample content item, and the description for each sample query tells you whether or not the query will retrieve the content item.