h:dataTable shows more and duplicated repeated items from the database

Question

I'm trying to display data from a database table named BOOKS in an h:dataTable that grabs its data from a method named getBooks().

public ArrayList<Book> getBooks() throws SQLException {
    if (ds == null) {
        throw new SQLException("ds is null; Can't get data source");
    }

    Connection conn = ds.getConnection();

    if (conn == null) {
        throw new SQLException("conn is null; Can't get db connection");
    }
    try {
        PreparedStatement ps = conn.prepareStatement(
                "select TITLE, AUTHOR, PRICE from BOOKS"
        );

        // retrieve customer data from database
        ResultSet result = ps.executeQuery();

        while (result.next()) {
            Book b = new Book();
            b.setTitle(result.getString("TITLE"));
            b.setAuthor(result.getString("AUTHOR"));
            b.setPrice(result.getDouble("PRICE"));
            books.add(b);
        }

    } finally {
        conn.close();
    }
    return books;
}

The SQL statement works fine and it retrieves the correct data, however when this JSF page runs:

<h:body>
    <center>
        <h1>Welcome to the Java Bookstore!</h1>
        <h:form>
            <h3>Inventory List</h3>
            <h:dataTable value="#{bookDatabase.books}" var="book" border="5" class="bookList">

                <h:column>
                    <f:facet name="header">Title</f:facet>
                    <h:outputText value="#{book.title}" />
                </h:column>
                <h:column>
                    <f:facet name="header">Author</f:facet>
                    <h:outputText value="#{book.author}" />
                </h:column>
                <h:column>
                    <f:facet name="header">Price</f:facet>
                    <h:outputText value="#{book.price}">
                        <f:convertNumber currencySymbol="$" groupingUsed="true"
                                         maxFractionDigits="2" type="currency"/>
                    </h:outputText>
                </h:column>

                <h:column>
                    <h:commandLink value="Add to Cart" 
                                   action="#{shoppingCart.add(book)}" >
                        <f:ajax render="@all"/>
                    </h:commandLink>
                </h:column>

            </h:dataTable>

        </h:form>
        <br/>
        <br/>
        <h3>Shopping Cart</h3>
        <h:form>
            <h:dataTable value="#{shoppingCart.box}" var="cart" border="5" class="shoppingCart">
                <h:column>
                    <f:facet name="header">Title</f:facet>
                    <h:outputText value="#{cart.title}" />
                </h:column>
                <h:column>
                    <f:facet name="header">Author</f:facet>
                    <h:outputText value="#{cart.author}" />
                </h:column>
                <h:column>
                    <f:facet name="header">Price</f:facet>
                    <h:outputText value="#{cart.price}">
                        <f:convertNumber currencySymbol="$" groupingUsed="true"
                                         maxFractionDigits="2" type="currency"/>
                    </h:outputText>
                </h:column>

                <h:column>
                    <f:facet name="header">Quantity</f:facet>
                    <h:outputText value="#{cart.quantity}" />
                </h:column>

                <h:column>
                    <h:commandLink value="Remove By One" action="#{shoppingCart.remove(cart)}" >
                        <f:ajax render="@form" />
                    </h:commandLink>
                </h:column>

            </h:dataTable>
            <br/>
            <h3>
                Total Price:
                <h:outputText value="#{shoppingCart.getTotal()}">
                    <f:convertNumber currencySymbol="$" groupingUsed="true"
                                     maxFractionDigits="2" type="currency"/>
                </h:outputText>
            </h3>


            <h:commandButton value="Checkout"
                             action="#{shoppingCart.checkout}"/>
        </h:form>
    </center>
</h:body>

It displays this table for the Inventory List that should only contain 4 elements, but seems to have iterated more than needed i.e. displaying the 4 books again in the table after reaching the last book.

Why is it giving me this bug? Is there something i'm not doing right?

Please move the business logic in its own place (I am avoiding this fact for no reason as of now). Here ``, you are calling a getter method [which invoke multiple times](http://stackoverflow.com/a/2090062/1391249) by nature in which you have placed the business logic. Migrate the code from that method to another place such as a method decorated with `@PostConstruct`. (Do not use deprecated HTML tags/attributes like `` which is highly discouraged). — Tiny, Feb 22 '15 at 05:23

h:dataTable shows more and duplicated repeated items from the database

0 Answers0