I’m going to duplicate some records in table tbl.
It looks like
INSERT INTO tbl SELECT id+100, name FROM tbl
in plain SQL.
I expected that it could look like
db.run(
tableQuery.forceInsertQuery(
tableQuery.map{rec=>rec.copy(id=rec.id+100)}
))
in Slick, where
rec is an instance of Table[ScalaCaseClassForTbl]
with
val id = column[Int]("id", O.PrimaryKey)
val name = column[String]("name")
and
override def * : ProvenShape[ScalaCaseClassForTbl] =
But I do not understand how to make map.
Thank you for any ideas.
The problem with...
tableQuery.map{rec=>rec.copy(id=rec.id+100)}
...is that rec is not a case class, so there's not a copy.
What you can do is map to a tuple of the columns (the Rep[T]) values) and then convert that to a case class.
For example:
tableQuery.map{ rec =>
(rec.id+100, rec.name).mapTo[YourCaseClass]
}
Related
I have following
case class Request(name:Option[String], age: Option[Int], address: Option[List[String]])
And I want to construct a query like this the conditions should apply if and only if the field is defined:
val req = Request(Some("abc"), Some(27), Some(List["add1", "add2"])
select name, age, email from user where name = "abc" AND age = 27 AND address in("add1", "add2");
I went through doobies documentation and found about fragments which allow me to do the following.
val baseSql: Fragment = sql"select name, age, email from user";
val nameFilter: Option[Fragment] = name.map(x => fr" name = $x")
val ageFilter: Option[Fragment] = age.map(x => fr" age = $x")
val addressFilter: Option[Fragment] = address.map(x => fr " address IN ( " ++ x.map(y => fr "$y").intercalate(fr",") ++ fr" )"
val q = baseSql ++ whereAndOpt(nameFilter, ageFilter, addressFilter)
from my understanding the query should look like this if all the fields are defined:
select name, age, email from user where name = "abc" AND age = 27 AND address in("add1","add2");
but the query looks like this:
select name, age, email from user where name = ? AND age = ? AND address in(?);
What is wrong here I am not able to find that.
Thanks in advance !!!!
Everything is fine.
Doobie prevents SQL injections by SQL functionality where you use ? in your query (parametrized query), and then pass the values that database should put into the consecutive ? arguments.
Think like this: if someone posted name = "''; DROP table users; SELECT 1". Then you'd end up with
select name, age, email from user where name = ''; DROP table users; SELECT 1
which could be a problem.
Since the database is inserting arguments for you, it can do it after the parsing of a raw text, when such injection is impossible. This functionality is used not only by Doobie but by virtually every modern library or framework that let you talk to database at level higher than plain driver.
So what you see is a parametrized query in the way that database will see it, you just don't see the parameters that will be passed to it.
In my use case I have a createdDate field that I would like to preserve in the event that the record already exists.
case class Record(id:Long, value:String, createdDate:DateTime, updateDate:DateTime)
Is it possible to use a TableQuery.insertOrUpdate(record) such that only parts of the record are updated in the event the record already exists?
In my case I'd want only the value and updateDate fields to change. Using plain SQL in a stored procedure I'd do something like:
merge Record r
using (
select #id,
#value
) as source (
id,
value
)
on r.id = source.id
when matched then
update set value = source.value, updateDate = getDate()
when not matched then
insert (id, value, createdDate, updatedDate) values
(id, value, getDate(), getDate()
Can Slick's insertOrUpdate modify a subset of columns?
No, I don't believe this is possible with the insertOrUpdate function. This has been requested as a feature but it is not currently implemented.
How can we work around this?
Since the update function does support updating a specific list of columns, we can write our own upsert logic instead of using the insertOrUpdate function. It might work like this:
def insertOrUpdate(record: Record): Future[Int] = {
val insertOrUpdateAction = for {
recordOpt <- records.filter(_.id === record.id).result.headOption
updateAction = recordOpt.map(_ => updateRecord(record))
action <- updateAction.getOrElse(insertRecord(record))
} yield action
connection.run(insertOrUpdateAction)
}
private def updateRecord(record: Record) = {
val query = for {
r <- records.filter(_.id === record.id)
} yield (r.value, r.updatedDate) // list of columns which can be updated
query.update(record.value, record.updatedDate)
}
private def insertRecord(record: Record) = records += record
I have a Field Field<T>. I want to create a named value for that field, to be able to use it in a query. The name of the value should be the name of the field.
select value as field from ...
Is the the correct way to do it?
public <T> Field<T> namedValue(Field<T> field, T value) {
return DSL.val(value, field).as(field);
}
Although it works, I was wondering if there is a shorter way to do this. I might be pedantic here :).
update
I am creating the following construction:
UPADTE table SET x = alias.x, y = alias.y
FROM (SELECT constant value for x, table2.y FROM table2 WHERE ...) AS alias.
Let's simplify this to (for the sake of this example, to focus on the constant selection):
SELECT
FROM (SELECT constant value for x) AS alias.
First, I started with:
Select s1 = context.select(DSL.val("TEST"));
Select s2 = context.select(s1.fields()).from(s1);
This resulted in an incorrect query:
select "alias_66794930"."TEST" from (select 'TEST') as "alias_66794930"
(I am not really sure if this is correct behavior from jOOQ.)
So, I added an alias:
Select s1 = context.select(DSL.val("TEST").as(X));
Select s2 = context.select(s1.fields()).from(s1);
This resulted in:
select "alias_76324565"."x" from (select 'TEST' as "x") as "alias_76324565"
This works fine. Then, I ran into problems when the constant vale was null:
Select s1 = context.select(DSL.val(null).as(X));
Select s2 = context.select(s1.fields()).from(s1);
This resulted in:
select "alias_85795854"."x" from (select cast(? as varchar) as "x") as "alias_85795854"
1400 [localhost-startStop-1] TRACE org.jooq.impl.DefaultBinding - Binding variable 1 : null (class java.lang.Object)
This makes sense, the field type is not known. So I added the field (with its type) as following:
Select s1 = context.select(DSL.val(null, X).as(X));
Select s2 = context.select(s1.fields()).from(s1);
Binding is now correct:
1678 [localhost-startStop-1] TRACE org.jooq.impl.DefaultBinding - Binding variable 1 : null (class java.lang.String)
All done!
I don't think you can get much shorter than what you already have. I mean, your SQL reads:
value as field
And your Java/jOOQ code reads:
DSL.val(value, field).as(field)
You could of course static import DSL.val or DSL.*:
import static org.jooq.impl.DSL.*;
And then shorten things to:
val(value, field).as(field)
And if you're very sure about value's type, you don't need to coerce it to that of field
val(value).as(field)
Now, you definitely can't go any shorter, and there's no more need for your namedValue() function...
My problem is simple.
I have a column seqNum: Double which is NOT NULL DEFAULT 1 in CREATE TABLE statement as follows:
CREATE TABLE some_table
(
...
seq_num DECIMAL(18,10) NOT NULL DEFAULT 1,
...
);
User can enter a value for seqNum or not from UI. So the accepting PLAY form is like:
case class SomeCaseClass(..., seqNum: Option[Double], ...)
val secForm = Form(mapping(
...
"seqNum" -> optional(of[Double]),
...
)(SomeCaseClass.apply)(SomeCaseClass.unapply))
The slick Table Schema & Objects looks like this:
case class SomeSection (
...
seqNum: Option[Double],
...
)
class SomeSections(tag: Tag) extends Table[SomeSection](tag, "some_table") {
def * = (
...
seqNum.?,
...
) <> (SomeSection.tupled, SomeSection.unapply _)
...
def seqNum = column[Double]("seq_num", O.NotNull, O.Default(1))
...
}
object SomeSections {
val someSections = TableQuery[SomeSections]
val autoInc = someSections returning someSections.map(_.sectionId)
def insert(s: someSection)(implicit session: Session) = {
autoInc.insert(s)
}
}
When I'm sending seqNum from UI, everything is works fine but when None is there, it breaks saying that cannot insert NULL in NOT NULL column which is correct. This question explains why.
But how to solve this problem using slick? Can't understand where should I check about None? I'm creating & sending an object of SomeSection to insert method of SomeSections Object.
I'm using sql-server, if it matters.
Using the default requires not inserting the value at all rather than inserting NULL. This means you will need a custom projection to insert to.
people.map(_.name).insert("Chris") will use defaults for all other fields. The limitations of scala's native tuple transformations and case class transformations can make this a bit of a hassle. Things like Slick's HLists, Shapeless, Scala Records or Scala XR can help, but are not trivial or very experimental at the moment.
Either you enforce the Option passed to Slick by suffixing it with a .getOrElse(theDefault), or you make the DB accepts NULL (from a None value) and defaults it using some trigger.
Customer.text is a field in an T-SQL DB (that I do not control and thus may not alter) of type "text".
I'd like to do something like this:
List<string> compare = new List<string>();
compare.Add("one");
compare.Add("two");
var q = from t in customer
where t.text.Contains( compare.First())
select t;
this will work.
But now I'd like to do something like: (!NOT WORKING!)
var q = from t in customer
where compare.Contains( t.text )
select t;
How can I achieve this? Is it even possible?
EDIT: The problem is obviously not exactly clear: A text column in SQL cannot be queried using "=" but only with LIKE. Thus the compare.Contains( t.text ) will result in an error, as it is converted into a query using "=".
What I did not tell - I thought it is irrelevant - is, that I use LINQ-to-ORM (LLBLGen in this case).
What I tried instead:
var q = from t in customer
where compare.Any( x => t.text.Contains(x) )
select t;
Now this did not work also. Currently I'm not at work, but the exception was something with a ConstantExpression not being convertable into a SetExpression.
I hope this gave some clarification.
EDIT2:
Joseph pointed this out to me: PredicateBuilder. It creates an Expression on a given ObjectType.
Now my problem is, that my type is an anonymous type out of multiple joins.
Is there an easy or elegant way to handle this?
Now I might be missing something, but your code looks like it should work. Did you include the namespaces at the top of the file?
using System.Linq;
using System.Linq.Expressions;
You could also rewrite it without the Linq2Sql syntax, like:
var q = customer.Where(c => compare.Contains(c.text));
You could build your query using LinqKit's free predicate builder class. Here is a blog post which describes its use and has a link to the download site.
http://thecodeslinger.wordpress.com/2008/10/28/linqkit-predicatebuildert-goodness/
Below is a code sample from the post
//First get a list of keywords that match the description entered.
string[] parts = txtInclude.Text.Split(new[] {‘ ‘});
string[] noparts = null;
if(txtButNot.Text.Trim().Length > 0)
noparts = txtExclude.Text.Trim().Split(new[] {‘ ‘});
var pred = PredicateBuilder.True<Pet>();
//here is where you would loop through your compare object
parts.ForEach(p => pred = pred.And(pl => pl.description.Contains(p)));
if(noparts != null)
noparts.ForEach(p => pred = pred.And(pl => !pl.description.Contains(p)));
var pets = from s in db.Pets.Where(pred)
select s;
You have to convert the text field to string
var query = from t in dataContext.table
where compare.Contains(t.textField.ToString())
select t;