Wicket has a flexible internationalisation system that supports parameterising UI messages in many ways. There are examples e.g. in StringResourceModel javadocs, such as this:
WeatherStation ws = new WeatherStation();
add(new Label("weatherMessage", new StringResourceModel(
"weather.${currentStatus}", this, new Model<String>(ws)));
But I want something really simple, and couldn't find a good example of that.
Consider this kind of UI message in a .properties file:
msg=Value is {0}
Specifically, I wouldn't want to create a model object (with getters for the values to be replaced; like WeatherStation in the above example) only for this purpose. That's just overkill if I already have the values in local variables, and there is otherwise no need for such object.
Here's a stupid "brute force" way to replace the {0} with the right value:
String value = ... // contains the dynamic value to use
add(new Label("message", getString("msg").replaceAll("\\{0\\}", value)));
Is there a clean, more Wicket-y way to do this (that isn't awfully much longer than the above)?
Take a look at Example 4 in the StringResourceModel javadoc - you can pass a null model and explicit parameters:
add(new Label("message",
new StringResourceModel(
"msg", this, null, value)));
msg=Value is {0}
I think the most consistent WICKETY way could be accomplished by improving Jonik's answer with MessageFormat:
.properties:
msg=Saving record {0} with value {1}
.java:
add(new Label("label", MessageFormat.format(getString("msg"),obj1,obj2)));
//or
info(MessageFormat.format(getString("msg"),obj1,obj2));
Why I like it:
Clean, simple solution
Uses plain Java and nothing else
You can replace as many values as you want
Work with labels, info(), validation, etc.
It's not completely wickety but it is consistent with wicket so you may reuse these properties with StringResourceModel.
Notes:
if you want to use Models you simply need to create a simple model that override toString function of the model like this:
abstract class MyModel extends AbstractReadOnlyModel{
#Override
public String toString()
{
if(getObject()==null)return "";
return getObject().toString();
}
}
and pass it as MessageFormat argument.
I don't know why Wicket does not support Model in feedback message. but if it was supported there was no reason to use these solutions and you could use StringResourceModel everywhere.
There's a way, which although still involves creating a model, doesn't requires a bean with a getter.
given this message in a properties file:
msg=${} persons
Here's how to replace the placeholder with a value, be it a local variable, a field or a literal:
add(new Label("label", new StringResourceModel("msg", new Model<Serializable>(5))));
When faced with something like described in the question, I would now use:
.properties:
msg=Saving record %s with value %d
Java:
add(new Label("label", String.format(getString("msg"), record, value)));
Why I like it:
Clean, simple solution
Uses plain Java and nothing else
You can replace as many values as you want (unlike with the ${} trick). Edit: well, if you actually need to support many languages where the replaced values might be in different order, String.format() is no good. Instead, using MessageFormat is a similar approach that properly supports this.
Disclaimer: this is "too obvious", but it's simpler than the other solutions (and definitely nicer than my original replaceAll() hack). I originally sought for a "Wicket-y" way, while this kinda bypasses Wicket—then again, who cares? :-)
In case you have a Model in your Component which holds an object with values you want to access from your placeholders as substitutions, you can write:
new StringResourceModel("salutation.text", getModel());
Let's imagine getModel()'s return type is IModel<User> and User contains fields like firstName and lastName. In this case you can easily access firstName and lastName fields inside your property string:
salutation.text=Hej ${firstName} ${lastName}, have a nice day!
Further information you can find here: https://ci.apache.org/projects/wicket/apidocs/8.x/org/apache/wicket/model/StringResourceModel.html#StringResourceModel-java.lang.String-org.apache.wicket.model.IModel-
Creating a Model for your Label really is The Wicket Way. That said, you can make it easy on yourself with the occasional utility function. Here's one I use:
/**
* Creates a resource-based label with fixed arguments that will never change. Arguments are wrapped inside of a
* ConvertingModel to provide for automatic conversion and translation, if applicable.
*
* #param The component id
* #param resourceKey The StringResourceModel resource key to use
* #param component The component from which the resourceKey should be resolved
* #param args The values to use for StringResourceModel property substitutions ({0}, {1}, ...).
* #return the new static label
*/
public static Label staticResourceLabel(String id, String resourceKey, Component component, Serializable... args) {
#SuppressWarnings("unchecked")
ConvertingModel<Serializable>[] models = new ConvertingModel[args.length];
for ( int i = 0; i < args.length; i++ ) {
models[i] = new ConvertingModel<Serializable>( new Model<Serializable>( args[i] ), component );
}
return new CustomLabel( id, new StringResourceModel( resourceKey, component, null, models ) );
}
Details I'm glossing over here are:
I've created my own ConvertingModel which will automatically convert objects to their String representation based on the IConverters available to the given component
I've created my own CustomLabel that applies custom label text post-processing (as detailed in this answer)
With a custom IConverter for, say, a Temperature object, you could have something like:
Properties key:
temperature=The current temperature is ${0}.
Page.java code:
// Simpler version of method where wicket:id and resourceKey are the same
add( staticResourceLabel( "temperature", new Temperature(5, CELSIUS) ) );
Page.html:
<span wicket:id='temperature'>The current temperature is 5 degrees Celsius.</span>
The downside to this approach is that you no longer have direct access to the Label class, you can't subclass it to override isVisible() or things like that. But for my purposes it works 99% of the time.
Related
When parsing options with the JOpt Simple library, the only way I know of accessing their respective types is by saving the OptionSpec instances somewhere and accessing them latter. For example:
OptionParser parser = new OptionParser();
ArgumentAcceptingOptionSpec<Path> pathOption = parser
.acceptsAll(Arrays.asList("p", "path"),
"Read message from a file")
.withRequiredArg()
.withValuesConvertedBy(new PathConverter());
/* We will use this one latter */
OptionSpec<Path> pathOptionSpec = pathOption;
OptionSet parsedOptions = parser.parse("-path", "./foo/bar");
/*
See? Unless I missed something, you need the pathOptionSpec object
(which is of type OptionSpec<Path>) to retrieve the "path"'s option type.
If I used .valueOf("path"), it would return
an OptionSet<?> and I would have to typecast it!
*/
assertThat(
parsedOptions.valueOf(pathOptionSpec),
instanceOf(OptionSpec<Path>.class));
Now, what I did was saving the OptionParser, the OptionSet and every OptionSpec as static members of the Main class, and access those options from anywhere in the program (you may now screech and raise your pitchforks now).
Is there a clean way to manage parsed CLI arguments in a typesafe way?
I migrating a Vaadin 8 project to Vaadin 14 and i try to show HTML in a grid column.
I figured out, that i have to use a TemplateRenderer, but how can i use it?
Here is the code from Vaadin 8:
grid.addColumn(e -> {
return ((Data) e).getValues()[index];
}).setCaption(myCaption).setRenderer(new HtmlRenderer());
In Vaadin 14 i did this:
gird.addColumn(e -> {
return TemplateRenderer.<Data>of((String) e.getValues()[index])
}).setHeader(myCaption);
e.getValues()[index] includes HTML, for example: <FONT SIZE = 4 COLOR = BLACK> ⚫</FONT>
In Vaadin 14 it always returns com.vaadin.flow.data.renderer.
Before we get to how to use a TemplateRenderer with Grid, I first need to point out that what you're trying to do is potentially dangerous because of the way it can lead to XSS vulnerabilities if the HTML strings that you want to show may be supplied by application users.
Using the Html component is indeed one potential solution to this problem, but it causes some overhead because there will be one component instance in memory for each row in the grid. There's also the same problem with potentially causing XSS vulnerabilities.
The first thing to notice with TemplateRenderer is that the renderer needs to be supplied directly as a parameter to addColumn. Wrapping it in a lambda will instead use that lambda as a value provider, which means that the toString() value of the renderer instance will be used with the default plain text renderer.
All rows should use the same renderer instance, configured with the same template string. The trick is that you can pass the data to show as a per-row property that the template will render for you. The last piece of the puzzle is that the template syntax tries to protect you against accidental XSS vulnerabilities, so you need to use a slightly contrived syntax to actually make it render the data as HTML.
Putting everything together, and also using JSoup to remove any dangerous stuff from your HTML strings, the working solution looks like this:
grid.addColumn(TemplateRenderer
.<Data> of("<div inner-h-t-m-l='[[item.html]]'></div>")
.withProperty("html", e -> {
String unsafeHtml = e.getValues()[index];
String safeHtml = Jsoup.clean(unsafeHtml, Whitelist.basic());
return safeHtml;
})).setHeader(myCaption);
I found a solution.
Instead of using the TemplateRenderer I used a ComponentRenderer.
The migration documentation recomented to use a TempleteRenderer or an ComponentRenderer instead of the htmlRenderer.
https://vaadin.com/docs/v14/flow/migration/8-migration-example.html#step-4-product-grid
Here is the code that worked for me:
grid.addColumn(new ComponentRenderer<>(e -> {
String value = (String) e.getValues()[index];
return new Html(value);
})).setHeader(String.valueOf(col + 1));
Comparing your attempts with TemplateRenderer and the documentation, I would assume it will have to look like this:
grid.addColumn(e ->
TemplateRenderer.<Data>of("[[item.customValue]]")
.withProperty("customValue", (String) e.getValues()[index])
).setHeader(myCaption);
In my maven-wicket (6.10) application I have a TextField, which has an Integer type property model. I want to set a maximum length for numberts to type into this TextField. (for example the user should write maximum 2 characters to the "age" text field)
I have tried this code:
add(new TextField<>("age",new PropertyModel<(personModel,"age"))
.add(StringValidator.maximumLength(2)));
//age is an Integer value from a Person class, personModel is "IModel<Person>" type
but I got this exception:
java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.String
at org.apache.wicket.validation.validator.StringValidator.getValue(StringValidator.java:87)
at org.apache.wicket.validation.validator.StringValidator.getValue(StringValidator.java:59)
at org.apache.wicket.validation.validator.AbstractRangeValidator.validate(AbstractRangeValidator.java:107)
at org.apache.wicket.markup.html.form.FormComponent.validateValidators(FormComponent.java:1523)
So if the property model is not string type, I cannot use StringValidator. I have found examples, which use NumberValidator (validators), but I cannot resolve NumberValidator. I have only these validators in the source:
How could I use number validator? Or am I missing something, maybe form the pom.xml's dependencies for wicket?
The problem you are facing is related to the way Wicket works. First it converts input text into a model object and then it performs validation.
Thus, you have to use RangeValidator instead of StringValidator
IModel<Integer> model =
new PropertyModel<Integer>(personModel, "age");
Component ageField = new TextField<Integer>("age", model);
add(ageField).add(RangeValidator.<Integer>range(0, 99));
Note I've changes Long to Integer as I believe saving age as Long is not practical.
Also note that link to NumberValidator is for Wicket 1.4, while you are using Wicket 6. Wicket 6 is a large API change comparing to previous versions.
For future reference please have a look at NumberTextField<N>
In Op's case, you could do more easily like:
IModel<Integer> model = new PropertyModel<Integer>(personModel, "age");
add(new NumberTextField<Integer>("age", model).setMinimum(0).setMaximum(99));
Was wondering why the constraints created for a form are not included in the input tag directly when created through the form helper?
Explanation (using Play 2.1):
Model:
public class Account {
#MaxLength(5)
private String id = "";
...
...
view:
#form(action = routes.Application.addAccount()) {
#inputText(accountForm("id"), '_label -> "Enter your id:")
}
renders automatically in html as:
Enter your id:
Maximum length: 5
Should it not render like this (actually constraining the form text field):
Enter your id:
Maximum length: 5
How can I get code that will automatically include constraints such as these in the form? It's just that I do not really think it is a good idea to have a maxlength defined in the form model and a separate one defined in the view.
Thanks
If I've understood you correctly, it sounds like you're looking to implement one of these features:
Highlight an input text field that is overlength before form submission
Clipping text in an input field so that it does not go overlength
Play's HTML templating engine doesn't natively provide this kind of client-side instant form validation. This functionality needs to be implemented via JavaScript, and JavaScript generation is not really a concern for Play.
If you want to progressively enhance your form and provide client-side validation, you'll have to write the JavaScript yourself. Of course there are libraries that you can use to help you with this task. For example, if you are already using jQuery you can use its validation plugin.
As you've mentioned in your question, it would be better to have a maximum length limit declared in one place only, rather than duplicated in your client-side JavaScript code and your server-side Java code. As a suggestion, you could keep the limit declared in Java code, but introduce a new action in your controller tier that returns a JSON response containing this limit. This action could then be called via AJAX when loading your form page.
EDIT
Didn't know about the maxlength attribute, thanks Saad. If you feed in your maximum length limit as an input parameter to your template, you can populate an input element's maxlength attribute as follows:
#(accountForm: Form[Account], maxLength: Int)
...
#form(action = routes.Application.addAccount()) {
...
#inputText(
field = accountForm("id"),
args = '_label -> "Enter your id:", 'maxlength -> maxLength
)
...
}
...
There may be a more elegant way to pass maxLength into your HTML template (e.g use the HTTP context map, or have it as a public field on your Account form object). The above code snippet just demonstrates how to correctly generate the input text field once you can access it in the template.
New to Java, and can't figure out what I hope to be a simple thing.
I keep "sections" in an array:
//Section.java
public static final String[] TOP = {
"Top News",
"http://www.mysite.com/RSS/myfeed.csp",
"top"
};
I'd like to do something like this:
Article a1 = new Article();
a1.["s_" + section[2]] = 1; //should resolve to a1.s_top = 1;
But it won't let me, as it doesn't know what "section" is. (I'm sure seasoned Java people will cringe at this attempt... but my searches have come up empty on how to do this)
Clarification:
My article mysqlite table has fields for the "section" of the article:
s_top
s_sports
...etc
When doing my import from an XML file, I'd like to set that field to a 1 if it's in that category. I could have switch statement:
//whatever the Java version of this is
switch(section[2]) {
case "top": a1.s_top = 1; break;
case "sports": a1.s_sports = 1; break;
//...
}
But I thought it'd be a lot easier to just write it as a single line:
a1["s_"+section[2]] = 1;
In Java, it's a pain to do what you want to do in the way that you're trying to do it.
If you don't want to use the switch/case statement, you could use reflection to pull up the member attribute you're trying to set:
Class articleClass = a1.getClass();
Field field = articleClass.getField("s_top");
field.set(a1, 1);
It'll work, but it may be slow and it's an atypical approach to this problem.
Alternately, you could store either a Map<String> or a Map<String,Boolean> inside of your Article class, and have a public function within Article called putSection(String section), and as you iterate, you would put the various section strings (or string/value mappings) into the map for each Article. So, instead of statically defining which sections may exist and giving each Article a yes or no, you'd allow the list of possible sections to be dynamic and based on your xml import.
Java variables are not "dynamic", unlink actionscript for exemple. You cannot call or assign a variable without knowing it at compile time (well, with reflection you could but it's far to complex)
So yes, the solution is to have a switch case (only possible on strings with java 1.7), or using an hashmap or equivalent
Or, if it's about importing XML, maybe you should take a look on JAXB
If you are trying to get an attribute from an object, you need to make sure that you have "getters" and "setters" in your object. You also have to make sure you define Section in your article class.
Something like:
class Article{
String section;
//constructor
public Article(){
};
//set section
public void setSection(Section section){
this.section = section;
}
//get section
public String getSection(){
return this.section;
}