Package org.eclipse.persistence.jpa.jpql.parser

Class IdentificationVariable

  • All Implemented Interfaces:
    Expression
    public final class IdentificationVariable
extends AbstractExpression
    An identification variable is a valid identifier declared in the FROM clause of a query.

    Requirements:

    • All identification variables must be declared in the FROM clause. Identification variables cannot be declared in other clauses.
    • An identification variable must not be a reserved identifier or have the same name as any entity in the same persistence unit.
    • Identification variables are case insensitive.
    • An identification variable evaluates to a value of the type of the expression used in declaring the variable.

    An identification variable can range over an entity, embeddable, or basic abstract schema type. An identification variable designates an instance of an abstract schema type or an element of a collection of abstract schema type instances.

    Note that for identification variables referring to an instance of an association or collection represented as a Map, the identification variable is of the abstract schema type of the map value.

    An identification variable always designates a reference to a single value. It is declared in one of three ways:

    • In a range variable declaration;
    • In a join clause;
    • In a collection member declaration.
    The identification variable declarations are evaluated from left to right in the FROM clause, and an identification variable declaration can use the result of a preceding identification variable declaration of the query string.

    All identification variables used in the SELECT, WHERE, ORDER BY, GROUP BY, or HAVING clause of a SELECT or DELETE statement must be declared in the FROM clause. The identification variables used in the WHERE clause of an UPDATE statement must be declared in the UPDATE clause.

    An identification variable is scoped to the query (or subquery) in which it is defined and is also visible to any subqueries within that query scope that do not define an identification variable of the same name.

    Version:
    2.4
    Author:
    Pascal Filion
    Since:
    2.3

    • Constructor Detail

      • IdentificationVariable

        public IdentificationVariable​(AbstractExpression parent,
                              java.lang.String identificationVariable)
        Creates a new IdentificationVariable.
        Parameters:
        parent - The parent of this expression
        identificationVariable - The actual identification variable

      • IdentificationVariable

        public IdentificationVariable​(AbstractExpression parent,
                              java.lang.String identificationVariable,
                              boolean virtual)
        Creates a new IdentificationVariable.
        Parameters:
        parent - The parent of this expression
        identificationVariable - The actual identification variable
        virtual - Determines whether this identification variable is virtual, meaning it's not part of the query but is required for proper navigability

    • Method Detail

      • getStateFieldPathExpression

        public StateFieldPathExpression getStateFieldPathExpression()
        Returns the actual representation of the parsed information. This method should only be called if isVirtual() returns true. This is valid in an UPDATE and DELETE queries where the identification variable is not specified.
        Returns:
        The path expression that is qualified by the virtual identification variable
        Throws:
        java.lang.IllegalAccessError - If this expression does not have a virtual identification variable

      • getText

        public java.lang.String getText()
        Returns the encapsulated text of this AbstractExpression, which can be used in various ways, it can be a keyword, a literal, etc.
        Overrides:
        getText in class AbstractExpression
        Returns:
        Either the JPQL identifier for this AbstractExpression, the literal it encapsulates or an empty string

      • getVariableName

        public java.lang.String getVariableName()
        Returns the identification variable, which has been changed to be upper case.
        Returns:
        The uppercase version of the identification variable
        Since:
        2.4

      • isVirtual

        public boolean isVirtual()
        Determines whether this AbstractExpression is virtual, meaning it's not part of the query but is required for proper navigability.
        Overrides:
        isVirtual in class AbstractExpression
        Returns:
        true if this AbstractExpression was virtually created to fully qualify path expression; false if it was parsed

      • parse

        protected void parse​(WordParser wordParser,
                     boolean tolerant)
        Parses the query by starting at the current position, which is part of the given WordParser.
        Specified by:
        parse in class AbstractExpression
        Parameters:
        wordParser - The text to parse based on the current position of the cursor
        tolerant - Determines whether the parsing system should be tolerant, meaning if it should try to parse invalid or incomplete queries

      • setVirtualIdentificationVariable

        public void setVirtualIdentificationVariable​(java.lang.String variableName)
        Sets a virtual identification variable because the abstract schema name was parsed without one. This is valid in an UPDATE and DELETE queries. This internally transforms the what was thought to be an identification variable to a path expression.
        Parameters:
        variableName - The identification variable that was generated to identify the "root" object

      • toParsedText

        protected void toParsedText​(java.lang.StringBuilder writer,
                            boolean actual)
        Generates a string representation of this Expression, including its children, if it has any.
        Specified by:
        toParsedText in class AbstractExpression
        Parameters:
        writer - The buffer used to append this Expression's string representation
        actual - Determines whether the string representation should represent what was parsed, i.e. include any "virtual" whitespace (such as ending whitespace) and the actual case of the JPQL identifiers