In your OptionModel, the label is the Brand description, and the value is the Brand itself.
You then supply a ValueEncoder that converts between Brands and brand ids (as strings, for the client side). If Brand is an entity object, then it may be necessary to have the ValueEncoder talk to the database or session store. On 5/4/07, Joel Wiegman <[EMAIL PROTECTED]> wrote:
Thanks for the reply Howard. >> The Select component doesn't know how to create a client-side representation of a Brand (it doesn't magically know to use the id). So, then... I guess my question would be... what is the BrandSelectModel for? In that object, I'm essentially mapping a Brand's "description" to the Brand object. Just curious what your thoughts are on that... -----Original Message----- From: Howard Lewis Ship [mailto:[EMAIL PROTECTED] Sent: Friday, May 04, 2007 1:42 PM To: Tapestry users Subject: Re: T5: SelectModel - a real world example In the simplest case, T5 thinks that the options in the drop down list are all strings. In your case, they are Brands. The Select component doesn't know how to create a client-side representation of a Brand (it doesn't magically know to use the id). You must provide a ValueEncoder that can convert between Brands and client-side string values. This is the encoder parameter of the Select component. On 5/4/07, Joel Wiegman <[EMAIL PROTECTED]> wrote: > > Not to be harsh, but I don't think I've ever written a select box with > constant values (Enum). Seems like even Male/Female drop downs need > to be data-driven now-a-days. :-> > > I've started to stub out a very simple "real world example" of a > select component in T5, but it doesn't appear to be as simple as I > thought it would be. > > A shiny nickel to anyone that can spot the flaw, because I sure can't... > I'm new to Tapestry in general so I could be missing something really > mundane here, but seems like it should work in my mind. > > Here are the players: > > << THE ERROR >> > > [ERROR] DefaultRequestExceptionHandler Processing of request failed > with uncaught exception: com.foo.data.Brand cannot be cast to > java.lang.String > java.lang.ClassCastException: com.foo.data.Brand cannot be cast to > java.lang.String > at > org.apache.tapestry.corelib.components.Select$1.toClient(Select.java:62) > at > org.apache.tapestry.corelib.components.Select.writeOptions(Select.java > :1 > 94) > at > org.apache.tapestry.corelib.components.Select.options(Select.java:169) > at > org.apache.tapestry.corelib.components.Select.beforeRenderTemplate(Sel > ec > t.java) > > > << Main.html (abridged) >> > > <t:form> > <select t:type="select" t:id="brand" value="brand" > model="brandSelectModel"/> > </t:form> > > > << Main.java (abridged) >> > > package com.foo.pages; > > import com.foo.data.Brand; > > public class Main { > > private Brand brand; > > public Brand getBrand() { > return brand; > } > > public void setBrand(Brand brand) { > this.brand = brand; > } > > public BrandSelectModel getBrandSelectModel() { > return new BrandSelectModel(getBrands()); > } > > public List<Brand> getBrands() { > List<Brand> brands = new ArrayList<Brand>(); > brands.add(new Brand("1", "Brand 1")); > brands.add(new Brand("2", "Brand 2")); > brands.add(new Brand("3", "Brand 3")); > return brands; > } > > } > > > << Brand.java (abridged) >> > > package com.foo.data; > > public class Brand { > > private String id; > private String description; > > public Brand() {} > > public Brand(String id, String description) { > this.id = id; > this.description = description; > } > > public String getId() { > return id; > } > > public String getDescription() { > return description; > } > > } > > > << BrandSelectModel.java >> > > package com.foo.uisupport; > > import com.foo.data.Brand; > > public class BrandSelectModel implements SelectModel { > > private List<Brand> brands; > > public BrandSelectModel(List<Brand> brands) { > this.brands = brands; > } > > public List<OptionGroupModel> getOptionGroups() { > return null; > } > > public List<OptionModel> getOptions() { > List<OptionModel> optionModelList = new > ArrayList<OptionModel>(); > for(Brand brand: brands) { > optionModelList.add(new > OptionModelImpl(brand.getDescription(), false, brand, new String[0])); > } > return optionModelList; > } > > } > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > -- Howard M. Lewis Ship TWD Consulting, Inc. Independent J2EE / Open-Source Java Consultant Creator and PMC Chair, Apache Tapestry Creator, Apache HiveMind Professional Tapestry training, mentoring, support and project work. http://howardlewisship.com --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
-- Howard M. Lewis Ship TWD Consulting, Inc. Independent J2EE / Open-Source Java Consultant Creator and PMC Chair, Apache Tapestry Creator, Apache HiveMind Professional Tapestry training, mentoring, support and project work. http://howardlewisship.com
