How to Dynamically Bind Lists Using Spring's Form Tag

How can I dynamically bind lists in a Spring MVC application using the form tag?

<form:form modelAttribute="myForm">
    <form:input path="name" />
    <form:repeat path="items" element="item">
        <form:input path="item.name"/>
        <form:input path="item.value"/>
    </form:repeat>
    <input type="submit" value="Submit" />
</form:form>

In a Spring MVC application, dynamically binding lists using the form tag allows you to handle collections of an object within a form submission. This is useful in scenarios where users need to enter varying numbers of items, such as a list of products or tags.

@Controller
public class MyController {
    @GetMapping("/form")
    public String showForm(Model model) {
        model.addAttribute("myForm", new MyForm());
        return "formPage";
    }

    @PostMapping("/form")
    public String submitForm(@ModelAttribute MyForm myForm) {
        // process form submission
        return "resultPage";
    }
}

Causes

• The need for users to enter a variable number of entities.
• Enhancing the user experience by allowing dynamic input of related fields.

Solutions

• Use Spring's `<form:repeat>` tag to render a collection of form elements for each entry in a list.
• Implement a corresponding controller method to handle dynamic binding of the list upon form submission.

Mistake: Forgetting to set the model attribute in the controller.

Solution: Ensure the model attribute is added before returning the view for the form.

Mistake: Not using the correct paths in the form binding.

Solution: Double-check paths in the repeat tag against your data model.