Getting the number of deleted rows in Kotlin's Exposed? - kotlin

I currently have something along the lines of
transaction {
FooTable.deleteWhere { FooTable.BarId eq 1 }
}
I want to see how many rows that it successfully deleted (I really just want to make sure there was an entry before and was deleted). Any ideas on how I can do that?

Try this:
transaction {
var numberOfDeletedItems = FooTable.deleteWhere { FooTable.BarId eq 1 }
}

Related

How do perform a graph query and join?

I apologize for the title, I don't exactly know how to word it. But essentially, this is a graph-type query but I know RavenDB's graph functionality will be going away so this probably needs to be solved with Javascript.
Here is the scenario:
I have a bunch of documents of different types, call them A, B, C, D. Each of these particular types of documents have some common properties. The one that I'm interested in right now is "Owner". The owner field is an ID which points to one of two other document types; it can be a Group or a User.
The Group document has a 'Members' field which contains an ID which either points to a User or another Group. Something like this
It's worth noting that the documents in play have custom IDs that begin with their entity type. For example Users and Groups begin with user: and group: respectively. Example IDs look like this: user:john#castleblack.com or group:the-nights-watch. This comes into play later.
What I want to be able to do is the following type of query:
"Given that I have either a group id or a user id, return all documents of type a, b, or c where the group/user id is equal to or is a descendant of the document's owner."
In other words, I need to be able to return all documents that are owned by a particular user or group either explicitly or implicitly through a hierarchy.
I've considered solving this a couple different ways with no luck. Here are the two approaches I've tried:
Using a function within a query
With Dejan's help in an email thread, I was able to devise a function that would walk it's way down the ownership graph. What this attempted to do was build a flat array of IDs which represented explicit and implicit owners (i.e. root + descendants):
declare function hierarchy(doc, owners){
owners = owners || [];
while(doc != null) {
let ownerId = id(doc)
if(ownerId.startsWith('user:')) {
owners.push(ownerId);
} else if(ownerId.startsWith('group:')) {
owners.push(ownerId);
doc.Members.forEach(m => {
let owner = load(m, 'Users') || load(m, 'Groups');
owners = hierarchy(owner, owners);
});
}
}
return owners;
}
I had two issues with this. 1. I don't actually know how to use this in a query lol. I tried to use it as part of the where clause but apparently that's not allowed:
from #all_docs as d
where hierarchy(d) = 'group:my-group-d'
// error: method hierarchy not allowed
Or if I tried anything in the select statement, I got an error that I have exceeded the number of allowed statements.
As a custom index
I tried the same idea through a custom index. Essentially, I tried to create an index that would produce an array of IDs using roughly the same function above, so that I could just query where my id was in that array
map('#all_docs', function(doc) {
function hierarchy(n, graph) {
while(n != null) {
let ownerId = id(n);
if(ownerId.startsWith('user:')) {
graph.push(ownerId);
return graph;
} else if(ownerId.startsWith('group:')){
graph.push(ownerId);
n.Members.forEach(g => {
let owner = load(g, 'Groups') || load(g, 'Users');
hierarchy(owner, graph);
});
return graph;
}
}
}
function distinct(value, index, self){ return self.indexOf(value) === index; }
let ownerGraph = []
if(doc.Owner) {
let owner = load(doc.Owner, 'Groups') || load(doc.Owner, 'Users');
ownerGraph = hierarchy(owner, ownerGraph).filter(distinct);
}
return { Owners: ownerGraph };
})
// error: recursion is not allowed by the javascript host
The problem with this is that I'm getting an error that recursion is not allowed.
So I'm stumped now. Am I going about this wrong? I feel like this could be a subquery of sorts or a filter by function, but I'm not sure how to do that either. Am I going to have to do this in two separate queries (i.e. two round-trips), one to get the IDs and the other to get the docs?
Update 1
I've revised my attempt at the index to the following and I'm not getting the recursion error anymore, but assuming my queries are correct, it's not returning anything
// Entity/ByOwnerGraph
map('#all_docs', function(doc) {
function walkGraph(ownerId) {
let owners = []
let idsToProcess = [ownerId]
while(idsToProcess.length > 0) {
let current = idsToProcess.shift();
if(current.startsWith('user:')){
owners.push(current);
} else if(current.startsWith('group:')) {
owners.push(current);
let group = load(current, 'Groups')
if(!group) { continue; }
idsToProcess.concat(group.Members)
}
}
return owners;
}
let owners = [];
if(doc.Owner) {
owners.concat(walkGraph(doc.Owner))
}
return { Owners: owners };
})
// query (no results)
from index Entity/ByOwnerGraph as x
where x.Owners = "group:my-group-id"
// alternate query (no results)
from index Entity/ByOwnerGraph as x
where x.Owners ALL IN ("group:my-group-id")
I still can't use this approach in a query either as I get the same error that there are too many statements.

Checking if update query affected rows perl

I have an "UPDATE" query and I want to check if this query has affected any rows and if it has I would like to send an email to myself. I'm not really experienced with perl or sql. (I'm using postgresql).
EDIT: I know that UPDATE returns "count" which tells how many rows if any have been updated, but I still don't know how to get to it.
The code looks like this:
my $updateQuery - //UPDATE query
if(//updateQuery has effected rows){
//send mail
}else
//do nothing
The problem is I don't know what to put into the if, what flag should I set? Is there any easy check that answers "has effected rows"?
Shortcut version using do()
my $update_query = '...';
my $ret = $dbh->do($update_query);
if ($ret) {
if ($ret eq '0E0') {
# no rows updated
} else {
# rows updated
}
} else {
# error
}
Full prepare()/execute() version.
my $update_query = '...';
my $sth = $dbh->prepare($update_query);
my $ret = $sth->execute;
if ($ret) {
if ($ret eq '0E0') {
# no rows updated
} else {
# rows updated
}
} else {
# error
}

Where clause using some field is not returning any rows in phonegap

I am finding one funny error but not sure whether that is my mistake or not. Below is my code for phonegap storage application. I have to fetch the records by one field in SELECT Query. If I try without where condition it s working but with where clause it is not working. Anyone have an idea on this?
function setDetailWordList()
{
db.transaction(SetDetailWords);
}
function SetDetailWords(tx)
{
alert("Qiuery executing...");
alert('SELECT * FROM DW_Words WHERE word = "'+word+'"');
tx.executeSql('SELECT * FROM DW_Words where word = "'+word+'"', [], SetDetailWordsSuccess);
}
function SetDetailWordsSuccess(tx,results)
{
alert(results.rows.length);
$('#words').html("").listview('refresh');
for (var i=0; i < results.rows.length; i++)
{
$('#words').append('<li><a><div>'+results.rows.item(i).explanation+'</div></a></li>');
}
$('#words').listview('refresh');
//AddEvents();
}

Is there any way to do multiple inserts/updates in Slick?

In sql we can do something like this:
INSERT INTO tbl_name (a,b,c) VALUES(1,2,3),(4,5,6),(7,8,9);
Is there any way to do multiple/bulk/batch inserts or updates in Slick?
Can we do something similar, at least using SQL plain queries ?
For inserts, as Andrew answered, you use insertALL.
def insertAll(items:Seq[MyCaseClass])(implicit session:Session) = {
(items.size) match {
case s if s > 0 =>
try {
// basequery is the tablequery object
baseQuery.insertAll(tempItems :_*)
} catch {
case e:Exception => e.printStackTrace()
}
Some(tempItems(0))
case _ => None
}
}
For updates, you're SOL. Check out Scala slick 2.0 updateAll equivalent to insertALL? for what I ended up doing. To paraphrase, here's the code:
private def batchUpdateQuery = "update table set value = ? where id = ?"
/**
* Dropping to jdbc b/c slick doesnt support this batched update
*/
def batchUpate(batch:List[MyCaseClass])(implicit session:Session) = {
val pstmt = session.conn.prepareStatement(batchUpdateQuery)
batch map { myCaseClass =>
pstmt.setString(1, myCaseClass.value)
pstmt.setString(2, myCaseClass.id)
pstmt.addBatch()
}
session.withTransaction {
pstmt.executeBatch()
}
}
In Slick, you are able to use the insertAll method for a Table. An example of insertAll is given in the Getting Started page on Slick's website.
http://slick.typesafe.com/doc/0.11.1/gettingstarted.html

Having difficulty with specific Future<T> query and collections with nHibernate.

For the sake of example, I am removing non-queried and non-essential data just to figure out how to do the initial query here.
I have a model structure like this.
class Path {
Guid Id { get; protected set; }
IList<Step> Steps { get; set; }
void AddStep(Step entity) {
// write up bidirectional association
}
}
class Step {
Guid Id { get; protected set; }
Path Path { get; set; }
// other data irreleveent
}
Now assuming 50000 steps, each with 5000 steps... I do realize I don't want to return all of them at once. But putting a limit on my query fetch isn't my real problem.
Here is the exact query I am attempting to use. I am getting the exception..
NHibernate.QueryException : duplicate alias: lpStep
----> System.ArgumentException : An item with the same key has already been added.
I'm not entirely sure how to handle this scenario. if I use a flat out Fetch on the Path query, I get Select+N errors from the NHibernate Profiler.
I do have batching enabled - but as far as I am aware, that only really applies to inserts, not retrievals. But in any case I am getting back these errors and not sure how to handle it. Any ideas?
using (var Transaction = Session.BeginTransaction()) {
Path lpPath = null;
Step lpStep = null;
var lpPaths = Session.QueryOver<Path>(() => lpPath)
.Take(50)
.Future<Path>();
var lpSteps = Session.QueryOver<Step>(() => lpStep)
.JoinAlias(() => lpPath.Steps, () => lpStep)
.Where(o => o.Path.Id == lpPath.Id)
.Take(12)
.Future<Step>();
Transaction.Commit();
foreach (var path in lpPaths) {
Console.WriteLine("{0} fetched {1} Steps",
path.Id, path.Steps.Count);
}
}
I basically want to say ..
Select (50) Paths, also, as a separate select but part of the same trip, Select the first (12) Steps that belong the previously selected Paths.
But if I use a flat out join, I get 110 rows, whereas I expect to have 2 tables, 1 of 50 rows, 1 of 600 rows.
Can someone explain to me what I am doing wrong?
mind you, I can do some minor alterations and the query runs, but it isn't 'optimized'. I can get the data I want, but it takes multiple trips and lazy loading. I can optimize the actual Path selection easily enough but it is those blasted Steps. If I just take a restrictive where clause out of the lpSteps query, it just returns the first 12 steps, not returning 12 steps for each query done.
I've looked at some of the other stack overflow posts on Future<T> and found them to look a lot like this. So I don't understand why it isn't working. I suspect that what is going on is this..
lpPaths runs.
lpSteps tries to run, first one succeeds.
lpSteps then tries to run again, finds it cannot redefine lpPaths.
Apocolypse
I'm really hoping someone smarter than me can enlighten me on the absolute most optimal way to write this.
i cant really understand what your use case is. why do you only need the first 12 Steps of each Path? What about batches of Steps to process
IList<Guid> pathIds;
while ((pathIds = QueryOver.For<Path>()
.Where(...)
.Projection(path => path.Id)
.SetmaxResults(100)).Count > 0)
{
int batch = 0;
const int batchsize = 600;
IList<Step> steps;
while ((steps = Session.QueryOver<Step>()
.Where(step => step.Path.Id).In(pathIds)
.Where(step => step. ...)
.SetFirstResult(batch * batchsize)
.Take(batchsize)
.List<Step>()).Count > 0)
{
DoSomething(steps);
batch++;
}
}