if (JToken.op_Explicit(apiConfig["finjVersion"]) < JToken.op_Explicit(latestData["finjVersion"]))
{
...
}
Error: JToken.explicit operator bool(JToken)': cannot call operator or accessor directly
I tried searching it in Newtonsoft's website or Microsoft and found nothing.
It looks like you are trying to invoke one of the explicit conversion operators of JToken to convert a JSON property value to a .NET primitive. In order to use these operators, you must use the explicit conversion syntax of c# to cast the value to the required primitive type. You must also choose an appropriate .NET primitive type to which to cast that corresponds to the JSON property value.
E.g. if the value of "finjVersion" is some integer such as "finjVersion" : 1 you should do:
if ((long)apiConfig["finjVersion"] < (long)latestData["finjVersion"])
{
//...
}
Demo #1 here.
If the value of "finjVersion" does not correspond to a .NET primitive, rather than casting you must use ToObject<T>() to deserialize to the required type. E.g. if "finjVersion" looks like "finjVersion":"1.1.2.0", you could deserialize to System.Version like so:
if (apiConfig["finjVersion"].ToObject<Version>() < latestData["finjVersion"].ToObject<Version>())
{
//...
}
Demo #2 here.
Related
I try to pass an object to th:onclick.
When I pass a string(afficherDetails() function), everything is ok
When I pass an object(afficherDetails2() function), in the called function the object seems ok but it is empty.
function afficherDetails(employee) {
console.log("afficher Details");
document.getElementById("detailledFirstNameDataLabelId").textContent = employee.firstName;
document.getElementById("detailledLastNameDataLabelId").textContent = employee.lastName;
document.getElementById("detailledAddressDataLabelId").textContent = employee.address;
document.getElementById("detailledTitleDataLabelId").textContent = employee.title;
document.getElementById("detailledManagerDataLabelId").textContent = employee.manager;
}
function afficherDetails2(name) {
console.log("afficher Details");
document.getElementById("detailledFirstNameDataLabelId").textContent = name;
}
<td><button th:data-parameter1="${employee}" th:onclick=" afficherDetails(this.getAttribute('data-parameter1')) ">details</button></label></td>
<!--td><button th:data-parameter1="${employee.firstName}" th:onclick=" afficherDetails2(this.getAttribute('data-parameter1')) ">details</button></label></td-->
</tr>
Is it a correct behavior ? Can't we pass a complex object and we can only pass simple object?
thanks for your answer
Short answer:
You can pass a complex object to a HTML attribute - but it will be reduced to a string by the object's toString() method.
Therefore, in your case, an attempt to do the following in JavaScript...
var something = employee.firstName;
...will do nothing because the function is passed a string not an object - and therefore employee.firstName will be undefined in JavaScript.
Longer answer:
Bear in mind a couple of points:
A HTML attribute expects to contain a string:
<button th:data-parameter1="SOME VALUE IN HERE" ... >
So, the attribute data-parameter1 will be populated by Thymeleaf using a string.
All Thymeleaf processing happens on the server. Thymeleaf removes all its processing directives from the template and replaces them with valid HTML. Your JavaScript does not have access to the original Java object - just to whatever representation of that object was added to the HTML by Thymeleaf.
Let's assume you use something such as:
th:data-parameter1="${employee.firstName}"
Assuming employee.firstName evaluates to a string (John) then that is what Thymeleaf will use to produce this:
data-parameter1="John"
But if you try this:
th:data-parameter1="${employee}"
Assuming employee is your custom Java bean, then Thymeleaf will call its toString() method to use as the string.
If you have not defined a toString() method in your Employee class, then the underlying Object.toString() method will be used - and you will see something like the following - a string representation of the unique object, based on the object's name and hash code:
data-parameter1="org.yourpackage.Employee#bcb8097"
You can provide your own implementation of toString() in your Employee class to provide more useful information. But it has to be a string which can be placed in a HTML attribute.
For example, if you pass an ArrayList to the button:
List<String> names = Arrays.asList("John", "Mary");
and:
th:data-parameter1="${names}"
then your HTML button will contain this:
data-parameter1="[John, Mary]"
because [John, Mary] is the result of how ArrayList has implemented its toString() method.
You can send a certain Java objects directly to JavaScript - see JavaScript serialization. But that is probably off-topic for this question.
One extra note: In the following:
th:onclick="afficherDetails(this.getAttribute('data-parameter1'));"
You are using th:onclick - but there are no Thymeleaf expressions in the attribute, so there is nothing for Thymeleaf to process. You can just use:
onclick="afficherDetails(this.getAttribute('data-parameter1'));"
In Vaadin 8 Framework, and Vaadin 10 Flow, the data-binding capability lets us provide a Converter to mediate between the widget’s expected data type (such as String for a TextField) and the data type of the backing bean property (such as Integer number).
In this example, the built-in Converter implementation StringToIntegerConverter is used.
binder
.forField( this.phaseField )
.withConverter(
new StringToIntegerConverter( "Must enter an integer number" )
)
.bind( Panel::getPhase , Panel::setPhase ) ;
But what about defining a Converter for other types? How can I easily define a short-and-sweet Converter? For example, a String-to-UUID converter. I want to show the canonical 36-character hex string in a TextField, and going the other direction, parse that string back into a UUID.
// String to UUID
UUID uuid = UUID.fromString( myString ) ;
// UUID to String
String myString = uuid.toString() ;
I see that Binder.BindingBuilder offers the pair of methods withConverter that both take a pair of SerializableFunction objects.
Binder.BindingBuilder::withConverter(SerializableFunction<TARGET,NEWTARGET> toModel, SerializableFunction<NEWTARGET,TARGET> toPresentation)
Binder.BindingBuilder::withConverter(SerializableFunction<TARGET,NEWTARGET> toModel, SerializableFunction<NEWTARGET,TARGET> toPresentation, String errorMessage)
➥ So how do I define the pair of SerializableFunction objects/classes?
I noticed that this interface lists a known subinterface ValueProvider<SOURCE,TARGET>. That looks familiar, and I have a hunch it is the key to easily defining a short simple converter. But I do not quite comprehend the syntax with lambdas and all that is going on here.
I am not asking how to write a class implementing Converter. I am asking how to write the pair of SerializableFunction arguments to pass to the Binder.BindingBuilder::withConverter methods listed above as bullet items.
Quoting that JavaDoc:
Interface Binder.BindingBuilder<BEAN,TARGET>
…
withConverter
default <NEWTARGET> Binder.BindingBuilder<BEAN,NEWTARGET> withConverter(SerializableFunction<TARGET,NEWTARGET> toModel, SerializableFunction<NEWTARGET,TARGET> toPresentation)
Maps the binding to another data type using the mapping functions and a possible exception as the error message.
The mapping functions are used to convert between a presentation type, which must match the current target data type of the binding, and a model type, which can be any data type and becomes the new target type of the binding. When invoking bind(ValueProvider, Setter), the target type of the binding must match the getter/setter types.
For instance, a TextField can be bound to an integer-typed property using appropriate functions such as: withConverter(Integer::valueOf, String::valueOf);
Type Parameters:
NEWTARGET - the type to convert to
Parameters:
toModel - the function which can convert from the old target type to the new target type
toPresentation - the function which can convert from the new target type to the old target type
Returns:
a new binding with the appropriate type
Throws:
IllegalStateException - if bind has already been called
You can do it by passing two lambda expressions to withConverter, so something like this:
binder.forField(textField)
.withConverter(text -> UUID.fromString(text), uuid -> uuid.toString())
.bind(/* ... */);
If you need a more complicated conversion, then the right-hand side of the lambda can be surrounded with brackets, e.g.
binder.forField(textField).withConverter( text -> {
if ( text == null ) {
return something;
} else {
return somethingElse;
}
}, uuid -> { return uuid.toString(); } )
.bind(/* ... */);
If you need your converter multiple times, I recommend creating a separate class implementing interface com.vaadin.data.Converter. However, using lambdas is possible, too, as you already know (see answer of #ollitietavainen). But this is not Vaadin specific, it's a Java 8+ feature you can read about e.g. here. Basically, you can use lambdas whereever an object implementing an interface with only one method is required.
I am using Realm for Swift. I have two Realm objects structures like this:
class outerObject : Object {
dynamic var innerObject : innerInfo?
}
class innerInfo : Object {
dynamic var sortId = 5
}
I want to make a query that gets every outerObject where the innerInfo is not nil and sortId equals 3.
Normally I would use something like:
realm.objects(outerObject).filter(predicate)
And then write a suitable NSPredicate but I do not hink that works with optionals. So what is the recommended method?
This query should work: realm.objects(outerObject).filter("innerObject.sortId = 3").
when innerObjc is nil, this will been broken. Expected object of type string for property '' on object of type '', but received: (null),the 2nd anwser is not the right anwser.
Is it possible to cast a command-line passed string object back to actual object?
I want to do the following, but throwing error can't cast.
Button objPro = (Button) sender;
cProduct cp = (cProduct) objPro.CommandArgument;
If no, then why?
This is what the string holds.
cProduct cpObj = (cProduct)e.Row.DataItem;
Button btnAddProduct = (Button)e.Row.FindControl("btnAddProduct");
if (btnAddProduct != null)
{
btnAddProduct.CommandArgument = cpObj.ToString();
}
You probably can't, because it's a string. It's not a cProduct (whatever that is - consider following .NET naming conventions and naming it Product instead).
Now you could do this if you had a explicit conversion operator in cProduct to create an instance from a string.
You haven't really explained what's in the string, or what's in the type - but if your cProduct type provides a ToString method which contains all the data in a reversible form, then you could easily write a method or a constructor to create the product again:
Product product = new Product(objPro.CommandArgument);
or maybe:
Product product = Product.Parse(objPro.CommandArgument);
You'll have to write that constructor/method, of course.
I would strongly recommend using a constructor or method instead of an operator, just to keep your code clearer - it's very rarely a good idea to write your own conversion operators.
Take a look at CommandArgument on MSDN. The property is a string, when you assign the a value to the property, you aren't casting some complex type to string, you are setting a string value on the property. Can you cast a string back to your object type anyway, regardless of it being a CommandArgument. I doubt it. If the argument is an int you could try int.Parse or similar for other types which have a parse method.
I need to log all the function parameters in a dozen functions.
Is there a way to pro grammatically determine all the parameters and their values (or at least their .ToString() value)? Perhaps via reflection?
Here is an example of how to do this with PostSharp
http://consultingblogs.emc.com/merrickchaffer/archive/2009/08/04/using-postsharp-to-log-method-entry-and-exit-in-net-code.aspx
You can also roll your own
http://www.developerfusion.com/article/5307/aspect-oriented-programming-using-net/3/
To the best of my knowledge there's no way to use reflection to dynamically list and determine value of local variables. You can use reflection to get type information about the parameters of a method, but only the declared type - you can't automatically get information about the actual arguments, because the reflection metadata gives information about the method definition, not the specific values passed to it at runtime.
You can, however, do something like this:
static class Extensions
{
public static string GetTypeAndValue(this object obj)
{
return String.Format("{0}: {1}", obj.GetType().Name, obj.ToString());
}
}
Then, from within each method in which you want to perform logging, do something like
private void SomeMethodToBeLogged(string some_string, int some_int, bool some_bool)
{
Logger.Log(String.Format("SomeMethodToBeLogged({0}, {1}, {2})",
some_string.GetTypeAndValue(),
some_int.GetTypeAndValue(),
some_bool.GetTypeAndValue()));
}