I want to get Row[N]<...> representation of a generated JOOQ table type. I want to use it in this context:
val p = PROJECTS.`as`("p")
val pmu = PROJECTMEMBERUSERS.`as`("pmu")
val query = db
.select(p.asterisk(), DSL.arrayAgg(DSL.rowField(<-- insert Row[N]<...> here -->)))
.from(p.join(pmu).on(p.ID.eq(pmu.PROJECTID)))
.groupBy(p.ID)
I already tried inserting pmu.fieldsRow(), but DSL.rowField(...) expects another parameter type.
Error:(39, 58) Kotlin: None of the following functions can be called with the arguments supplied [...]
This question is a follow up question to Using PosgreSQL array_agg with join alias in JOOQ DSL but should be self contained.
Missing feature in jOOQ 3.11
There seems to be a missing feature in the jOOQ code generator, a generated Table.fieldsRow() overridden method that provides a more narrow, covariant Row[N]<...> return type. I've created a feature request for this, to be implemented in jOOQ 3.12:
https://github.com/jOOQ/jOOQ/issues/7809
Also missing, an overloaded DSL.rowField(RowN) method:
https://github.com/jOOQ/jOOQ/issues/7810
Workaround, list columns explicitly
This is the most obvious workaround, which you obviously want to avoid: Listing all the column names explicitly:
row(pmu.COL1, pmu.COL2, ..., pmu.COLN)
Workaround, use generated records
There already is such a generated method in generated records. As a workaround, you could use
new ProjectMembersUsersRecord().fieldsRow();
Workaround, extend the code generator
You can implement #7809 yourself already now, by extending the JavaGenerator with a custom code section:
https://www.jooq.org/doc/latest/manual/code-generation/codegen-custom-code
Related
When using Telosys to generate entities with the java7-persistence-commons-jpa-T300 templates the column annotation never includes columnDefinition when generating the #Column annotation in JpaRecord-classes. That forces database schemageneration with hbm2ddl always to generate VARCHAR columns.
But when the origin database column is an CHAR-column the generated record-class should also generate columnDefinition... i.e.: #Column(columnDefinition = "CHAR(xx)", name = "VVT_NR", nullable = false, length = 20)
Is there a way to force telosys to generate the columnDefinition (with correct length for xx of course)?
The JPA function "$jpa.fieldAnnotations()”
used in the mentioned template is a shortcut to generate the "classical" JPA annotations for a given field and indeed it doesn’t generated all the “#Column” optional elements (for example “table”, “insertable”, “updatable” and “columnDefinition” are not generated)
In version 3 there's no way to force the generator to produce the "columnDefinition".
But if you really want to generate the “columnDefinition” you can create a specific function or a specific macro.
To create a Velocity macro see :
http://www.telosys.org/templates-doc/velocity/macro.html
http://people.apache.org/~henning/docbook/html/ch07.html
To create a specific function see this other question :
Is it possible in a Telosys template to call a function created specifically?
For a specific function you can reuse the "$jpa" class source code :
https://github.com/telosys-tools-bricks/telosys-tools-generator/blob/master/src/main/java/org/telosys/tools/generator/context/Jpa.java
It seems I'm unable to use a method reference of an object in Kotlin. This feature exists in Java.
For example in Java if I was looping through a string to append each character to a writer:
string.forEach(writer::append);
But in Kotlin using the same syntax does not work because:
For now, Kotlin only supports references to top-level and local functions and members of classes, not individual instances. See the docs here.
So, you can say Writer::append and get a function Writer.(Char) -> Writer, but taking a writer instance and saying writer::append to get a function (Char) -> Writer is not supported at the moment.
Starting from Kotlin 1.1 writer::append is a perfectly valid bound callable reference.
However, you still cannot write string.forEach(writer::append) because Writer#append method returns a Writer instance and forEach expects a function that returns Unit.
I am using Kotlin 1.3 and while referencing a Java method I got a very similar error. As mentioned in this comment, making a lambda and passing it to the forEach method is a good option.
key.forEach { writter.append(it) }
Being it the implicit name of a single parameter.
I have two functions: one returns a list of fields, the other returns a select query (which selects the corresponding values of the fields).
private List<Field<?>> fields() {
....
}
private Select<?> select() {
...
}
Note that the degree is determined at runtime, it depends on the user input. Hence List<Field<?>> and Select<?>.
It is possible to insert into a table:
context.insertInto(table, fields()).select(select()))
It is not possible to update a table:
context.update(table).set(DSL.row(fields()), select())
Could this functionality be added to jOOQ 3.7?
Which workaround can we use for now?
Nice catch, there's a missing method on the UpdateSetFirstStep DSL API, which accepts RowN as a first argument, the type returned from DSL.row(Collection). This should be fixed for jOOQ 3.7:
https://github.com/jOOQ/jOOQ/issues/4475
As a workaround, and if you can live with the guilt of the hack, you could cast to raw types:
context.update(table).set((Row1) DSL.row(fields()), (Select) select())
You can cast DSL.row(fields()) to Row1, because the internal implementation type returned by DSL.row(fields()) implements all Row[N] types.
I've a simple class like this:
Public Class CalculationParameter{
public Long TariffId{get;set;}
}
In a workflow activity, I've an Assign like this:
(From tariffDetail In db.Context.TariffDetails
Where tariffDetial.TariffId = calculationParameter.TariffId).FirstOrDefault()
Dto is passed to Activity as an Input Argument.
It raise following error and I'm wondering how to assign Id. Any Idea?
LINQ to Entities does not recognize the method 'Int64
GetValue[Int64](System.Activities.LocationReference)' method, and this
method cannot be translated into a store expression.
How can I assign the calculationParameter.TariffId to tariffDetial.TariffId?!
UPDATE:
Screen shot attached shows that how I'm trying to assign calculationParameter.TariffId to tariffDetail.TariffId (car.Id = Dto.Id) and the query result should assign to CurrentTrafficDetail object.
Here's your problem. I don't know if there is a solution to it.
As you said in a (now deleted, unfortunately necessitating that I answer) comment, the exception you're getting is
LINQ to Entities does not recognize the method Int64 GetValue[Int64](System.Activities.LocationReference) method, and this method cannot be translated into a store expression.
in your Linq query, calculationParameter is a Variable defined on the workflow. That Variable is actually an instance that extends the type System.Activities.LocationReference and NOT CalculationParameter.
Normally, when the workflow executes, the LocationReference holds all the information it needs to find the value which is assigned to it. That value isn't retrieved until the last possible moment. At runtime, the process of retrieval (getting the executing context, getting the value, converting it to the expected type) is managed by the workflow.
However, when you introduce Linq into the mix, we have the issue you are experiencing. As you may or may not know, your expression gets compiled into the extension method version of the same.
(From tariffDetail In db.Context.TariffDetails
Where tariffDetial.TariffId = calculationParameter.TariffId)
.FirstOrDefault()
is compiled to
db.Context.TariffDetails
.Where(x => x.TariffId = calculationParameter.TariffId)
.FirstOrDefault();
When this executes, L2E doesn't actually execute this code. It gets interpreted and converted into a SQL query which is executed against the database.
As the interpreter isn't omniscient, there are a well defined set of limitations on what methods you can use in a L2S query.
Unfortunately for you, getting the current value of a LocationReference is not one of them.
TL:DR You cannot do this.
As for workarounds, the only thing I think you can do is create a series of extension methods on your data context type or add methods to your CalculationParameter class that you can call from within the Expression Editor. You can create your Linq to Entities queries within these methods, as all types will already have been dereferenced by the workflow runtime, which means you won't have to worry about the L2E interpreter choking on LocationReferences.
*Edit: A workaround can be found here (thanks to Slauma who mentioned this in a comment on the question)
Consider the following line of code:
private void DoThis() {
int i = 5;
var repo = new ReportsRepository<RptCriteriaHint>();
// This does NOT work
var query1 = repo.Find(x => x.CriteriaTypeID == i).ToList<RptCriteriaHint>();
// This DOES work
var query1 = repo.Find(x => x.CriteriaTypeID == 5).ToList<RptCriteriaHint>();
}
So when I hardwire an actual number into the lambda function, it works fine. When I use a captured variable into the expression it comes back with the following error:
No mapping exists from object type
ReportBuilder.Reporter+<>c__DisplayClass0
to a known managed provider native
type.
Why? How can I fix it?
Technically, the correct way to fix this is for the framework that is accepting the expression tree from your lambda to evaluate the i reference; in other words, it's a LINQ framework limitation for some specific framework. What it is currently trying to do is interpret the i as a member access on some type known to it (the provider) from the database. Because of the way lambda variable capture works, the i local variable is actually a field on a hidden class, the one with the funny name, that the provider doesn't recognize.
So, it's a framework problem.
If you really must get by, you could construct the expression manually, like this:
ParameterExpression x = Expression.Parameter(typeof(RptCriteriaHint), "x");
var query = repo.Find(
Expression.Lambda<Func<RptCriteriaHint,bool>>(
Expression.Equal(
Expression.MakeMemberAccess(
x,
typeof(RptCriteriaHint).GetProperty("CriteriaTypeID")),
Expression.Constant(i)),
x)).ToList();
... but that's just masochism.
Your comment on this entry prompts me to explain further.
Lambdas are convertible into one of two types: a delegate with the correct signature, or an Expression<TDelegate> of the correct signature. LINQ to external databases (as opposed to any kind of in-memory query) works using the second kind of conversion.
The compiler converts lambda expressions into expression trees, roughly speaking, by:
The syntax tree is parsed by the compiler - this happens for all code.
The syntax tree is rewritten after taking into account variable capture. Capturing variables is just like in a normal delegate or lambda - so display classes get created, and captured locals get moved into them (this is the same behaviour as variable capture in C# 2.0 anonymous delegates).
The new syntax tree is converted into a series of calls to the Expression class so that, at runtime, an object tree is created that faithfully represents the parsed text.
LINQ to external data sources is supposed to take this expression tree and interpret it for its semantic content, and interpret symbolic expressions inside the tree as either referring to things specific to its context (e.g. columns in the DB), or immediate values to convert. Usually, System.Reflection is used to look for framework-specific attributes to guide this conversion.
However, it looks like SubSonic is not properly treating symbolic references that it cannot find domain-specific correspondences for; rather than evaluating the symbolic references, it's just punting. Thus, it's a SubSonic problem.