I'm including dynamic content to a view using a custom Thymeleaf attribute processor that simply adds additional nodes while processing the attribute itself.
The code I use is very similar to the one below:
final Template template = arguments.getTemplateRepository().getTemplate(
new TemplateProcessingParameters(arguments.getConfiguration(), "name-of-a-view", arguments.getContext()));
final List<Node> children = template.getDocument().getChildren();
// Add to the tree.
for (final Node node : children) {
element.addChild(node);
}
This works fine, but breaks when the included nodes contains forms that use th:object and th:field.
I put the model I need inside the node variable map and in fact th:object does find and retrieves the object, but th:field does not seems to care and breaks with a
Neither BindingResult nor plain target object for bean name 'model' available as request attribute
From my understanding (step-by-step debugging), it seems to me that th:field only search for the model in the request context.
Am I missing something here?
Thank you in advance.
No, you're spot on. I'm still not sure why the binding is different for th:field than other th: attributes, but it definitely works differently. Essentially, you can't use th:field unless your th:object is on the model. The workaround is to stop using th:field and just specify your input attributes manually, like:
<form action="#" th:action="#{/process}" th:object="${objectFromList}" method="post">
<input type="text" id="fieldName" name="fieldName" th:value="*{fieldName}" />
</form>
I realize this post is old. Hopefully, this will help someone who is running into this quirk.
Related
I have a strongly typed view where one of the properties of the model that is passed in is a list of objects. I am handling dynamic binding of inputs to this list by using the BeginCollectionItem helper which works fine. However, I also want to initially have a group of inputs visible on the view that will bind to the 'first' object in the list.
I've tried just copying the inputs that BeginCollectionItem generates but that doesn't seem to work.
It generates inputs with name attributes like
invoiceItems[ef43a8f2-c6b7-4791-bf7f-6764c8e3fc9b].Description
invoiceItems[ef43a8f2-c6b7-4791-bf7f-6764c8e3fc9b].Cost
so I manually put 2 inputs on the view with the name attributes
invoiceItems[firstOne].Description
invoiceItems[firstOne].Cost
but it didn't show up in the model on the controller after submitting the form.
I can't just insert one the BeginCollectionItem way when the view loads because the initial item has to be displayed differently.
Not exactly answer to your question, but I hope it will solve your problem.
Instead of changing the name in the view, you may try changing the model. Add a boolean property IsFirst. I believe you know in the controller(or wherever the model is being instantiated) which one is first. Set the first items IsFirst to true.
I figured it out. I was on the right track with manually putting in the stuff that BeginCollectionItem did, I was just missing a part. You need another hidden input that tells the binding what the index you're using is.
So the following works perfectly
<input type="hidden" name="invoiceItems.index" autocomplete="off" value="firstOne" />
<input type="text" placeholder = "ex. Labour" id="invoiceItems_firstOne__Description" name="invoiceItems[firstOne].Description" />
<input type="text" placeholder = "ex. $15" id="invoiceItems_firstOne__Cost" name="invoiceItems[firstOne].Cost" />
I just added the top hidden input to what I had before and it's all good.
In a work around I've used in the past, I've used the id field to pass an additional parameter that I needed. But I need to pass three parameters through a remoteField and now am presented with the fact I need to find a way to pass these parameters:
<g:remoteField action="updateFields" update="theDiv" id-"${personInstance.id}" paramName="search" name="updateFields" value="" />
Need: The search field (search), the person id (id), and now I need the company the person works for (c_id).
I can do something like this:
<g:remoteField action="updateFields" update="theDiv" id-"${personInstance.id}" paramName="search" name="updateFields" value="" params="${[c_id:c_id, search:/'+this.value+/']}"/>
If I try to obtain the search value with the params, the search field is now '+this.value+'. Can I just pass the object search field as an addition param in the map (like above) by referencing this.value? If so, what am I doing wrong, since my gsp doesn't load.
Edit
My current work around is to tie both IDs in a ID field, split by a delimiter and then broken into an array once it reaches the controller (obviously not ideal!)
Although I don't use remoteField, I do use remoteFunction frequently and have found I can use multiple javascript based variables directly with the 'params' parameter. E.g.
<script>
function someJSFunction(id1,id2,id3) {
<g:remoteFunction action="ajax_function" params="{id1:id1,id2:id2,id3:id3}" update="someDiv"/>
}
</script>
Hope that helps.
Having just spent two amazingly frustrating hours formatting some hidden fields to bind properly to action method parameters -- the second time I've had this experience in the last week -- I'm now very curious as to why the MVC architects chose the particular binding convention that they did for lists (and dictionaries) of objects.
Here's my painfully gathered understanding of the format expected by the default binding engine. In my example I want to bind to a List, where the CustomClass type exposes a public property called PropertyName:
<input type="hidden" name="prefix[idx].PropertyName" value="PropertyName[idx] Value" />
prefix is the ViewDataDictionary.TemplateInfo.HtmlPrefix, if one has been defined.
I find it deeply counter-intuitive to start the reference to something with the indexing information (i.e., the [idx] piece). I also find it disturbing that nowhere in this construct do I make reference to the name of the action method parameter to which I'm binding. That seems to be in direct contrast to what happens with, say, a primitive model property:
<input type="hidden" name="Text" value="something" />
public ActionResult SomeActionMethod( string Text )...
I understand I can roll my own model binder in MVC. That doesn't seem like a profitable use of my time, although spending hours trying to puzzle out the correct format for hidden fields isn't profitable either :), so maybe I'll try that. I also know that I can let MVC do all the heavy lifting by creating a type template using #Html.HiddenFor(), and then outputting instances of CustomClass though a simple partial view that has CustomClass as a model and the single line #Html.DisplayForModel(). But that seems like going the long way around the barn, too. Besides, there are limitations to using the #Html.Hidden helpers (e.g., they "helpfully" raid the cache after postback to fill in values, so writing #Html.Hidden("fieldname", value) doesn't guarantee value will end up being output -- you may get the older value in the cache instead, which was another hour-long annoyance today).
But I'm mostly just curious why this format was chosen. Why not something more C/C++/C#/VB like:
<input name="prefix.ParameterName.PropertyName[idx]" />
Edit:
Good point on where I put the index parameter in my example. You're right, the property isn't indexed, the containing class is.
However, that doesn't change the basic situation. Why isn't the syntax something like:
<input name="prefix.ParameterName[0].PropertyName" />
The standard syntax ignores the parameter name with collections of custom types, and "guesses" the custom type from the property names. That's bizarre...so there must be a story or choice behind it :).
Actually, it makes perfect sense. The index is into the collection, not the property. You don't have a collection of PropertyName, you have a Collection of CollectionName[] that has a PropertyName.
To put this another way:
public class Foo { public string Bar { get; set; } }
var foos = List<Foo>();
for (var i = 0; i < foos.Length; i++)
{
var prop = foos[i].Bar; // This is the important bit
}
That's exactly what happens in the model binder.
When the model binder deserializes the post values, it has to know which collection to insert the values into, and it has to know what index each item is for. So it has to know to create a Collection of Foos, of x number of items, and which indexes each Bar is associated with.
I have a collection of objects on my Model that I'm rendering in a View by using EditFor function, and I have an EditorTemplate which is responsible for actually rendering each object.
#Html.EditorFor(model => model.MyObjects)
This has worked well for a while now, and when you check the html, my text boxes are prefixed with the model property, followed by the index of the collection they came from.
<input class="text-box single-line" id="MyObjects_2__SomeProperty"
name="MyObjects[2].SomeProperty" type="Text" value="" />
However I've recently started using the ShowForEdit and ShowForDisplay properties in the model metadata for the collection, and in the first line of my editor template if the ShowForEdit is not true, I just skip it.
#if (!ViewData.ModelMetadata.ShowForEdit)
{
return;
}
But because these are all indexed in the html, when I try to save this collection back to the viewmodel via a postback, it fails because of a reliance on the indexing numbers. Every item in the collection after the missing index is missing from my view model when I check it's value.
In this case it's actually my first item in the collection that I'm skipping since I don't want it to be visible on the edit view, but because of this when I postback the first index in the html is 1 (instead of 0 like it normally would be), but this is a problem when you try to save the changes. This is also a problem when altering the DOM using javascript.
Has anyone else encountered a problem with the default model binder's ability to read data posted back when one or more indexes in the html represented collection are not present?
Are there model binders that handle this problem?
Ran into this issue recently and solved it by converting the List to a Dictionary<string, model> with GUIDs as the key.
#foreach (var index in Model.EmailAddresses.Keys)
{
<label asp-for="#Model.EmailAddresses[index].Email">Email</label>
<input asp-for="#Model.EmailAddresses[index].Email" type="text" />
}
This avoided having to include hidden inputs that map to the index value.
There are some very good blog posts that allow you to modelbind to a list without the need to provide zero based contiguous index. plz have a look at
http://blog.stevensanderson.com/2010/01/28/editing-a-variable-length-list-aspnet-mvc-2-style/
http://zahidadeel.blogspot.com/2011/05/master-detail-form-in-aspnet-mvc-3-ii.html
Furthermore, if you are interested in MVVM pattern and knockout js you can check this great work by steve sanderson
For more reading put "editing varibale length list mvc style" in google and it will give u a dozen useful links
I'm coming from a Spring MVC background on a new Grails app. I have an object that contains a list of dependent objects. On the create and edit screen, I want to edit that object and its list of objects at the same time. In Spring MVC, you could use special names to bind the form fields to items in a list. Example:
Entity { String name, List items }
<form:input name="entity.items[0].value" value="${entity.items[0].value}"/>
I've tried similar variations in my GSP create and edit forms, but no luck.
I haven't used this with tag (is it a Java taglib?), but what you are doing is along the right path. I don't think you need the entity in there, the name should be just "items[0].value"
Here is some code I have that does what you need (using HTML input tag):
<input type="text" name="subItems[0].date"/>