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Version: 5.x

How-to: Trees

Example 1​

Task​

We have a set of books associated with certain categories.

CLASS Category 'Category';
name 'Name' = DATA ISTRING[50] (Category);

CLASS Book 'Book';
name 'Name' = DATA ISTRING[50] (Book);
category 'Category' = DATA Category (Book);

We need to build a form with a tree, where the category is shown above and the product is shown below.

Solution​

FORM books 'Books'
    TREE cb c = Category, b = Book
    PROPERTIES name(c), name(b)
    FILTERS category(b) == c
;

Example 2​

Task​

Similar to Example 1, except that each category has a parent in the hierarchy.

parent 'Parent' = DATA Category (Category);

We need to build a form with a tree, where the categories will be displayed as hierarchy.

Solution​

FORM categories 'Categories'
    TREE categories c = Category PARENT parent(c)
    PROPERTIES(c) name
;

Example 3​

Task​

Similar to Example 2.

We need to create a form with a category tree, so that the books that belong to the current category and all its subcategories are shown to the right.

Solution​

level 'Level' (Category child, Category parent) = RECURSION 1l IF child IS Category AND parent == child
                                                                 STEP 2l IF parent == parent($parent) MATERIALIZED;

FORM categoryBooks 'Books by category'
    TREE categories c = Category PARENT parent(c)
    PROPERTIES(c) name

    OBJECTS b = Book
    PROPERTIES(b) name
    FILTERS level(category(b), c)
;

DESIGN categoryBooks {
    NEW pane FIRST {
        fill = 1;
        type = SPLITH;
        MOVE BOX(TREE categories);
        MOVE BOX(b);
    }
}