I just want to know if I can do below pertaining to custom component
1) I created a sample component
somComponent://foo ---> what this foo refers to?can i have any string there?
What does it denotes?
2) consider below route
from("some blah")
.to(someCustomComponent://action1)
.to(someCustomComponent://action2);
Idea - I want to perform two different actions on the above. Kind of two different methods.
Is the above possible?
The notation for your custom component in Apache Camel can be described as follows:
someComponent://instance?parm1=foo&parm2=bar
The instance part can be pretty much anything you want to uniquely identify the endpoint.
You can derive DefaultComponent and implement the methods. The signature for createEndpoint method looks like this:
protected Endpoint createEndpoint(final String uri, String remaining,
Map<String, Object> parameters) throws Exception
So for the endpoint someComponent://instance?parm1=foo&parm2=bar
uri = someComponent://instance?parm1=foo&parm2=bar
remaining = instance
parmeters = (Map) parm1 -> foo, parm2 -> bar
Therefore, yes! You can easily denote the action you want, for example as a parameter such as:
someComponent://instance?action=something
Related
Suppose I have two tables USER_GROUP and USER_GROUP_DATASOURCE. I have a classic relation where one userGroup can have multiple dataSources and one DataSource simply is a String.
Due to some reasons, I have a custom RecordMapper creating a Java UserGroup POJO. (Mainly compatibility with the other code in the codebase, always being explicit on whats happening). This mapper sometimes creates simply POJOs containing data only from the USER_GROUP table, sometimes also the left joined dataSources.
Currently, I am trying to write the Multiset query along with the custom record mapper. My query thus far looks like this:
List<UserGroup> = ctx
.select(
asterisk(),
multiset(select(USER_GROUP_DATASOURCE.DATASOURCE_ID)
.from(USER_GROUP_DATASOURCE)
.where(USER_GROUP.ID.eq(USER_GROUP_DATASOURCE.USER_GROUP_ID))
).as("datasources").convertFrom(r -> r.map(Record1::value1))
)
.from(USER_GROUP)
.where(condition)
.fetch(new UserGroupMapper()))
Now my question is: How to create the UserGroupMapper? I am stuck right here:
public class UserGroupMapper implements RecordMapper<Record, UserGroup> {
#Override
public UserGroup map(Record rec) {
UserGroup grp = new UserGroup(rec.getValue(USER_GROUP.ID),
rec.getValue(USER_GROUP.NAME),
rec.getValue(USER_GROUP.DESCRIPTION)
javaParseTags(USER_GROUP.TAGS)
);
// Convention: if we have an additional field "datasources", we assume it to be a list of dataSources to be filled in
if (rec.indexOf("datasources") >= 0) {
// How to make `rec.getValue` return my List<String>????
List<String> dataSources = ?????
grp.dataSources.addAll(dataSources);
}
}
My guess is to have something like List<String> dataSources = rec.getValue(..) where I pass in a Field<List<String>> but I have no clue how I could create such Field<List<String>> with something like DSL.field().
How to get a type safe reference to your field from your RecordMapper
There are mostly two ways to do this:
Keep a reference to your multiset() field definition somewhere, and reuse that. Keep in mind that every jOOQ query is a dynamic SQL query, so you can use this feature of jOOQ to assign arbitrary query fragments to local variables (or return them from methods), in order to improve code reuse
You can just raw type cast the value, and not care about type safety. It's always an option, evne if not the cleanest one.
How to improve your query
Unless you're re-using that RecordMapper several times for different types of queries, why not do use Java's type inference instead? The main reason why you're not getting type information in your output is because of your asterisk() usage. But what if you did this instead:
List<UserGroup> = ctx
.select(
USER_GROUP, // Instead of asterisk()
multiset(
select(USER_GROUP_DATASOURCE.DATASOURCE_ID)
.from(USER_GROUP_DATASOURCE)
.where(USER_GROUP.ID.eq(USER_GROUP_DATASOURCE.USER_GROUP_ID))
).as("datasources").convertFrom(r -> r.map(Record1::value1))
)
.from(USER_GROUP)
.where(condition)
.fetch(r -> {
UserGroupRecord ug = r.value1();
List<String> list = r.value2(); // Type information available now
// ...
})
There are other ways than the above, which is using jOOQ 3.17+'s support for Table as SelectField. E.g. in jOOQ 3.16+, you can use row(USER_GROUP.fields()).
The important part is that you avoid the asterisk() expression, which removes type safety. You could even convert the USER_GROUP to your UserGroup type using USER_GROUP.convertFrom(r -> ...) when you project it:
List<UserGroup> = ctx
.select(
USER_GROUP.convertFrom(r -> ...),
// ...
I want to generate a custom named constructor in Dart.
I have many dto class to implement and each should provide a named constructor like: ClassName.fromMap().
For example for this class:
class Student {
final String name;
final int age;
}
The generated constructor should be:
Student.fromMap(Map<String, dynamic> map) :
name = map['name'],
age = map['age'];
How can I retrieve the list of the field of my current class as strings? Is that even possibile?
Of course I can have a variable number of fields.
My template looks like:
$CLASS$.fromMap(Map<String, dynamic> map) :
$INITIALIZATION_LIST$
binding $CLASS$ to dartClassName().
Now I'd like to bind $INITIALIZATION_LIST$ to something like:
getClassFieldList().forEach((fieldName) => "$fieldName = map['$fieldName']")
Can I achieve something like that?
There is no way to retrieve a list of Dart class fields using predefined live template functions. You can try developing your own template macro for this. See https://intellij-support.jetbrains.com/hc/en-us/community/posts/206201699-create-a-new-expression-for-a-live-template-for-actionscript for some hints.
Existing live template functions implementations can be found at https://github.com/JetBrains/intellij-community/tree/master/platform/lang-impl/src/com/intellij/codeInsight/template/macro.
You can also try using Structural Search and Replace instead of live template
We want to implement a character counter in our Javascript data entry form, so the user gets immediate keystroke feedback as to how many characters he has typed and how many he has left (something like "25/100", indicating current string length is 25 and 100 is the max allowed).
To do this, I would like to write a service that returns a list of dto property names and their max allowed lengths.
{Name='SmallComment', MaxLength=128}
{Name='BigComment', MaxLength=512}
The best way I can think of to do this would be to create an instance of the validator for that dto and iterate through it to pull out the .Length(min,max) rules. I had other ideas as well, like storing the max lengths in an attribute, but this would require rewriting all the validators to set up the rules based on the attributes.
Whatever solution is best, the goal is to store the max length for each property in a single place, so that changing that length affects the validation rule and the service data passed down to the javascript client.
If you want to maintain a single source of reference for both client/server I would take a metadata approach and provide a Service that returns the max lengths to the client for all types, something like:
public class ValidationMetadataServices : Service
{
public object Any(GetFieldMaxLengths request)
{
return new GetFieldMaxLengthsResponse {
Type1 = GetFieldMaxLengths<Type1>(),
Type2 = GetFieldMaxLengths<Type2>(),
Type3 = GetFieldMaxLengths<Type3>(),
};
}
static Dictionary<string,int> GetFieldMaxLengths<T>()
{
var to = new Dictionary<string,int>();
typeof(T).GetPublicProperties()
.Where(p => p.FirstAttribute<StringLengthAttribute>() != null)
.Each(p => to[p.PropertyName] =
p.FirstAttribute<StringLengthAttribute>().MaximumLength);
return to;
}
}
But FluentValidation uses Static properties so that would require manually specifying a rule for each property that validates against the length from the property metadata attribute.
# student.rb
has_and_belongs_to_many :courses
# course.rb
has_and_belongs_to_many :students
I'm trying to create a scope in the students model that will check if they are enrolled in a course.
The best I've come up with is:
scope :unenrolled, where(Student.courses.count => 0)
But then I get the error message
undefined method `courses'
Anybody offer any suggestions?
Alright then. So here's your code:
scope :unenrolled, where(Student.courses.count => 0)
The first problem here is the thing that's causing the error: You're calling the instance method courses on the class Student. As the name implies, you can only call an instance method on an instance of a class, not on the class itself. For example:
jim = Student.find(123)
jims_courses = jim.courses
But here's the kicker: When you call scope you're in the class context, i.e. the code isn't inside an instance method, so it gets called when your model is first declared. There's no instance at that time so you can't just call courses like you would from within one of Student's instance methods.
But that's kind of moot since you've slightly misunderstood how where works. The argument(s) you give to where are supposed to be conditions that correspond to what you would put after WHERE in an SQL query. For example where(:eye_color => 'brown') will be turned into an SQL WHERE clause like WHERE eye_color = 'brown'. :eye_color => 'brown' is just a Hash with the key :eye_color whose value is 'brown'. Calling a function on the left side of => doesn't make sense unless the function returns the name of a column/attribute in your model that ActiveRecord will understand.
So now let's figure out what you should do. If you were writing an SQL query it would look something like this:
SELECT `students`.*, COUNT(`courses_students`.*) AS `courses_count`
FROM `students`
JOIN `courses_students` ON `students`.`id` = `courses_students`.`student_id`
WHERE `courses_count` = '0'
GROUP BY `courses_students`.`student_id`;
This translates roughly to an ActiveRecord query like this:
Student.joins(:courses). // AR automatically joins courses though courses_students
select('students., COUNT(courses.) AS courses_count').
where('courses_count = 0').
group('id')
And you can plunk that directly into your scope:
scope :unenrolled, joins(:courses).
select('students.*, COUNT(courses.*) AS courses_count').
where('courses_count = 0').
group('courses.course_id')
Note: These queries are a bit off-the-cuff and may require a bit of tweaking. The easiest way to build complicated ActiveRecord queries is by entering them directly into the Rails console until you get the results you want.
Hope that's helpful!
I want to call a function on a bean with an argument passsed to it in jsp using EL.
The problem is it does not allow something like:
"${teacherBean.certificationFor(${particularField})"
the thing is i want to iterate over an array and call the function certificationFor for all the values in the array passed as an argument.
I am getting the values in array by:
So Basically i want to do something like:
${teacherBean.certificationFor(${particularField})
but i cant do that.
can i do this in any other way?
I am a newbie in EL . :)
Any help is appreciated.
Where exactly do you want to do that and for what? Just to get a value for display? At least, in standard EL prior to Java EE 6 you cannot pass method arguments like that. In JBoss-EL or in Java EE 6 EL you can do that. The syntax would then just have been:
${teacherBean.certificationFor(particularField)}
Note that you cannot nest EL expressions, an EL expression is already a whole expression at its own.
In standard EL implementations you can however access Map values by keys using the brace notation. Thus, if you for example have a Map<String, String> certifications where the keys corresponds the particularField and the values the associated value:
private Map<String, String> certifications = new HashMap<String, String>();
public Map<String, String> getCertificationFor() {
return this.certifications;
}
then you can use the following notation:
${teacherBean.certificationFor[particularField]}
this resolves behind the scenes to
teacherBean.getCertificationFor().get(particularField)
I think in the standard EL you don't have any options other than defining your functions wrapped in a EL function;
Read: http://java.sun.com/j2ee/1.4/docs/tutorial/doc/JSPIntro7.html near the bottom of the
document;
but as BalusC mentioned already if you could use another EL implmentation if you have the ability to add that kind of dependency to your app
What about:
${teacherBean.certificationFor(particularField)}
If you are accessing a general functionality that is better expressed as a separate function, then you can write it as follows:
${certificationFor[teacherBean][particularField]}
where certificationFor maps to the CertificationFor class which extends ELMethod.java class. You implement the functionality in the result(Object[] args) method. The args to this method are the args that you passed to the ${certificationFor} object in EL.
public class CertificationFor extends ELMethod {
public Object result(Object[] args) {
TeacherBean teacherBean = (TeacherBean) args[0];
String property = (String) args[1];
// your implementation goes here
return ....;
}
}
The trick is to use your object as a chained map of maps, that is one way to pass multiple args to EL function.
If you are interested, you can see full code and code snippets here:
http://www.vineetmanohar.com/2010/07/how-to-pass-parameters-in-el-methods/