Re: error building Expressions: Can't resolve path component

From: Andrus Adamchik (andru..bjectstyle.org)
Date: Mon May 02 2005 - 09:29:38 EDT

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    Hi Zvonimir,

    The cleanest way is probably to use a Category object as a match parameter:

       Category catgeory = // ... obtain this object instead of usig id
       Expression e = ExpressionFactory.matchExp("hasCategory", category);

    However if you want to match on an id, you should use "DB" flavor of
    expressions. E.g.:

       Expression e = ExpressionFactory.matchDbExp("hasCategory.id", categoryId);

    BTW, if you use Expression.fromString, Cayenne is using "db:" prefix to
    distinguish between object and database path (e.g: "db:hasCategory.id").

    Hope this helps.

    Andrus

    > I tried something out, and is
    > this the best solution?
    >
    > Without defining the id in the path (hasCategory.id), only write
    > hasCategory:
    >
    > ...
    > Expression qual_2 = ExpressionFactory.matchExp("hasCategory",
    > categoryId); ...
    >
    > Greets
    > Zvonimir
    >
    >
    >
    > On Mon, 02 May 2005 15:06:38 +0200, Zvonimir Spajic
    > <z.spaji..scensys.de> wrote:
    >
    >> Hello,
    >>
    >> 1) why it's not allowed to build an expression like this
    >> --> see qual_2 (error message: "Can't resolve path component:
    >> [Category.id]")
    >>
    >> ...
    >> Expression qual_1 = Expression.fromString(SomeObject.NAME_PROPERTY + "
    >> likeIgnoreCase '%" + name + "%'");
    >> Expression qual_2 = ExpressionFactory.matchExp("hasCategory.id",
    >> categoryId);
    >> qual_1 = qual_1.andExp(qual_2);
    >> SelectQuery query = new SelectQuery(SomeObject.class, qual_1);
    >> ...
    >>
    >> -id is the PK-Column of category table
    >>
    >> 2) what is the best solution in this cases.
    >>
    >> Thanks for help
    >> Zvonimir Spajic

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