I need to get top 10 rows for each group in a table with entity framework.
Based on other solution on SO, I tried 2 things:
var sendDocuments = await context.Set<DbDocument>
.Where(t => partnerIds.Contains(t.SenderId))
.GroupBy(t => t.SenderId)
.Select(t => new
{
t.Key,
Documents = t.OrderByDescending(t2 => t2.InsertedDateTime).Take(10)
})
.ToArrayAsync();
error:
System.InvalidOperationException: 'The LINQ expression
'(GroupByShaperExpression: KeySelector: (d.SenderId),
ElementSelector:(EntityShaperExpression:
EntityType: DbDocument
ValueBufferExpression:
(ProjectionBindingExpression: EmptyProjectionMember)
IsNullable: False ) )
.OrderByDescending(t2 => t2.InsertedDateTime)' could not be translated. Either rewrite the query in a form that can be translated,
> or switch to client evaluation explicitly by inserting a call to
> either AsEnumerable(), AsAsyncEnumerable(), ToList(), or
> ToListAsync().
and
var sendDocuments2 = await context.Set<DbDocument>
.Where(t => partnerIds.Contains(t.SenderId))
.GroupBy(t => t.SenderId)
.SelectMany(t => t.OrderByDescending(t2 => t2.InsertedDateTime).Take(10))
.ToArrayAsync();
error:
System.InvalidOperationException: 'Processing of the LINQ expression
't => t
.OrderByDescending(t2 => t2.InsertedDateTime)
.AsQueryable()
.Take(10)' by 'NavigationExpandingExpressionVisitor' failed. This may indicate either a bug or a limitation in EF Core.
Any other idea?
Update (EF Core 6.0):
EF Core 6.0 added support for translating GroupBy result set projection, so the original code for taking (key, items) now works as it should, i.e.
var query = context.Set<DbDocument>()
.Where(e => partnerIds.Contains(e.SenderId))
.GroupBy(e => e.SenderId)
.Select(g => new
{
g.Key,
Documents = g.OrderByDescending(e => e.InsertedDateTime).Take(10)
});
However flattening (via SelectMany) is still unsupported, so you have to use the below workaround if you need such query shape.
Original (EF Core 3.0/3.1/5.0):
This is a common problem, unfortunately not supported by EF Core 3.0/3.1/5.0 query translator specifically for GroupBy.
The workaround is to do the groping manually by correlating 2 subqueries - one for keys and one for corresponding data.
Applying it to your examples would be something like this.
If you need (key, items) pairs:
var query = context.Set<DbDocument>()
.Where(t => partnerIds.Contains(t.SenderId))
.Select(t => t.SenderId).Distinct() // <--
.Select(key => new
{
Key = key,
Documents =
context.Set<DbDocument>().Where(t => t.SenderId == key) // <--
.OrderByDescending(t => t.InsertedDateTime).Take(10)
.ToList() // <--
});
If you need just flat result set containing top N items per key:
var query = context.Set<DbDocument>()
.Where(t => partnerIds.Contains(t.SenderId))
.Select(t => t.SenderId).Distinct() // <--
.SelectMany(key => context.Set<DbDocument>().Where(t => t.SenderId == key) // <--
.OrderByDescending(t => t.InsertedDateTime).Take(10)
);
I want to get all layergroups and include (eager loading) layers that have a specific url.
Here are my tables:
- LayerGroup (id, List<Layer>layers and more...)
- Layer(id, url, List<Attribute>attributes and more...)
- Attribute (id and more...)
This is what i got so far.
var groups = _context.LayerGroups
.Where(group => group.IsActive)
.Where(g => g.Layers.All(l => l.IsActive == true))
.Where(g => g.Layers.All(l => l.Url == "example1"))
.Include(g => g.Layers)
.ThenInclude(layer => layer.Attributes)
.Include(group => group.Layers).ThenInclude(layer => layer.SearchEngines)
.ToList();
But it seems to only get groups if exactly all layers is active and have the url example1. I want to get the layers with the right Url, even if the groups have layers with other url:s.
According to this you cannot filter Include and ThenInclude collection but you can filter parent with the condition based on Include. If you need so then you can write your query as follows:
var groups = _context.LayerGroups.Where(group => group.IsActive)
.Include(g => g.Layers)
.ThenInclude(layer => layer.Attributes)
.Include(group => group.Layers)
.ThenInclude(layer => layer.SearchEngines)
.Where(g => g.Layers.Any(l => l.IsActive == true && l => l.Url == "example1"))
.ToList();
I'm trying to add the attribute autocomplete="off" in mediawiki login form. Being completely new, I'm unable to find where the form is being built.
I'm using MediaWiki 1.29.1
Any help would be greatly appreciated.
Things I did to find it:
1. Added the following code in LocalSettings.php
$wgHooks['UserLoginForm'][] = 'modifyLoginForm';
function modifyLoginForm( &$template ) {
//Printed template and got the following
/*
UserloginTemplate Object
(
[data] => Array
(
[link] =>
[header] =>
[name] => Admin
[password] =>
[retype] =>
[email] =>
[realname] =>
[domain] =>
[reason] =>
[action] => /mediawiki/index.php?title=Special:UserLogin&action=submitlogin&type=login&returnto=Main+Page
[message] =>
[messagetype] => error
[createemail] =>
[userealname] => 1
[useemail] => 1
[emailrequired] =>
[emailothers] => 1
[canreset] => 1
[resetlink] => 1
[canremember] => 1
[usereason] =>
[remember] =>
[cansecurelogin] =>
[stickHTTPS] =>
[token] => 18955182baa69e0a66edefghi4e0ef
[loginend] =>
[signupend] =>
[usedomain] =>
)
*/
}
Tried to modify includes/templates/Userlogin.php . There is a login form, but it didn't get affected.
Checked LoginSignupSpecialPage.php, but not sure how to add the attribute.
I have nested entities like Property -> Facility -> Farm -> License etc.
I want to get the most recent license and my original query looks like this.
return _db.Properties
.Include(c => c.Contact)
.Include(f => f.Facilities.Select(c => c.Contact))
.Include(f => f.Facilities.Select(ff => ff.Farms.Select(s => s.Species)))
.Include(x => x.Facilities.Select(l => l.Licenses))
.SingleOrDefault(x => x.PropertyID == id);
Since I want to get the most recent license I tried
return _db.Properties
.Include(c => c.Contact)
.Include(f => f.Facilities.Select(c => c.Contact))
.Include(f => f.Facilities.Select(ff => ff.Farms.Select(s => s.Species)))
.Include(x => x.Facilities.Select(l => l.Licenses.OrderByDescending(d => d.IssueDate)))
.SingleOrDefault(x => x.PropertyID == id);
which fails of course because you cant use an orderby clause there.
If I try an orderby clause at the end of the linq it will start at Property and I will need to drill down to the licenses again.
What is the preferred convention for this?
--EDIT--
Based on Robert's suggestion I flipped the query to get the Licenses first but I guess I need to do some projection since this query only gives me the Property entity and no child entities.
return _db.Licenses.OrderByDescending(x => x.IssueDate)
.Include(f => f.Facility)
.Include(f => f.Facility.Property)
.Include(f => f.Facility.Property.Contact)
.Include(c => c.Facility.Contact)
.Include(f => f.Facility.Farms)
.Include(f => f.Facility.Farms.Select(s => s.Species))
.Where(x => x.Facility.Property.PropertyID == id)
.Select(x => x.Facility.Property).SingleOrDefault();
Any ideas to get all children?
I'm using Search::Elasticsearch and Search::Elasticsearch::Scroll for search and scroll into my elasticsearch server.
In scrolling process, for some querys, I'm seeing the next errors while I'm scrolling the search results:
2016/03/22 11:03:38 - 265885 FATAL: [Daemon.pm][8221]: Something gone wrong, error $VAR1 = bless( {
'msg' => '[Missing] ** [http://localhost:9200]-[404] Not Found, called from sub Search::Elasticsearch::Scroll::next at searcher.pl line 92. With vars: {\'body\' => {\'hits\' => {\'hits\' => [],\'max_score\' => \'0\',\'total\' => 5215},\'timed_out\' => bless( do{\\(my $o = 0)}, \'JSON::XS::Boolean\' ),\'_shards\' => {\'failures\' => [{\'index\' => undef,\'reason\' => {\'reason\' => \'No search context found for id [4920053]\',\'type\' => \'search_context_missing_exception\'},\'shard\' => -1},{\'index\' => undef,\'reason\' => {\'reason\' => \'No search context found for id [5051485]\',\'type\' => \'search_context_missing_exception\'},\'shard\' => -1},{\'index\' => undef,\'reason\' => {\'reason\' => \'No search context found for id [4920059]\',\'type\' => \'search_context_missing_exception\'},\'shard\' => -1},{\'index\' => undef,\'reason\' => {\'reason\' => \'No search context found for id [5051496]\',\'type\' => \'search_context_missing_exception\'},\'shard\' => -1},{\'index\' => undef,\'reason\' => {\'reason\' => \'No search context found for id [5051500]\',\'type\' => \'search_context_missing_exception\'},\'shard\' => -1}],\'failed\' => 5,\'successful\' => 0,\'total\' => 5},\'_scroll_id\' => \'c2NhbjswOzE7dG90YWxfaGl0czo1MjE1Ow==\',\'took\' => 2},\'request\' => {\'serialize\' => \'std\',\'path\' => \'/_search/scroll\',\'ignore\' => [],\'mime_type\' => \'application/json\',\'body\' => \'c2Nhbjs1OzQ5MjAwNTM6bHExbENzRDVReEc0OV9UMUgzd3Vkdzs1MDUxNDg1OnJrQ3lsUkRKVHRxRWRWeURoOTB4WVE7NDkyMDA1OTpscTFsQ3NENVF4RzQ5X1QxSDN3dWR3OzUwNTE0OTY6cmtDeWxSREpUdHFFZFZ5RGg5MHhZUTs1MDUxNTAwOnJrQ3lsUkRKVHRxRWRWeURoOTB4WVE7MTt0b3RhbF9oaXRzOjUyMTU7\',\'qs\' => {\'scroll\' => \'1m\'},\'method\' => \'GET\'},\'status_code\' => 404}
',
'stack' => [
[
'searcher.pl',
92,
'Search::Elasticsearch::Scroll::next'
]
],
'text' => '[http://localhost:9200]-[404] Not Found',
'vars' => {
'body' => {
'hits' => {
'hits' => [],
'max_score' => '0',
'total' => 5215
},
'timed_out' => bless( do{\(my $o = 0)}, 'JSON::XS::Boolean' ),
'_shards' => {
'failures' => [
{
'index' => undef,
'reason' => {
'reason' => 'No search context found for id [4920053]',
'type' => 'search_context_missing_exception'
},
'shard' => -1
},
{
'index' => undef,
'reason' => {
'reason' => 'No search context found for id [5051485]',
'type' => 'search_context_missing_exception'
},
'shard' => -1
},
{
'index' => undef,
'reason' => {
'reason' => 'No search context found for id [4920059]',
'type' => 'search_context_missing_exception'
},
'shard' => -1
},
{
'index' => undef,
'reason' => {
'reason' => 'No search context found for id [5051496]',
'type' => 'search_context_missing_exception'
},
'shard' => -1
},
{
'index' => undef,
'reason' => {
'reason' => 'No search context found for id [5051500]',
'type' => 'search_context_missing_exception'
},
'shard' => -1
}
],
'failed' => 5,
'successful' => 0,
'total' => 5
},
'_scroll_id' => 'c2NhbjswOzE7dG90YWxfaGl0czo1MjE1Ow==',
'took' => 2
},
'request' => {
'serialize' => 'std',
'path' => '/_search/scroll',
'ignore' => [],
'mime_type' => 'application/json',
'body' => 'c2Nhbjs1OzQ5MjAwNTM6bHExbENzRDVReEc0OV9UMUgzd3Vkdzs1MDUxNDg1OnJrQ3lsUkRKVHRxRWRWeURoOTB4WVE7NDkyMDA1OTpscTFsQ3NENVF4RzQ5X1QxSDN3dWR3OzUwNTE0OTY6cmtDeWxSREpUdHFFZFZ5RGg5MHhZUTs1MDUxNTAwOnJrQ3lsUkRKVHRxRWRWeURoOTB4WVE7MTt0b3RhbF9oaXRzOjUyMTU7',
'qs' => {
'scroll' => '1m'
},
'method' => 'GET'
},
'status_code' => 404
},
'type' => 'Missing'
}, 'Search::Elasticsearch::Error::Missing' );
The code I'm using is the next one (simplified) :
# Retrieve scroll
my $scroll = $self->getScrollBySignature($item);
# Retrieve all affected documents ids
while (my #docs = $scroll->next(500)) {
# Do stuff with #docs
}
The function getScrollBySignature have the next code in order to call to elasticSearch
my $scroll = $self->{ELASTIC}->scroll_helper(
index => $self->{INDEXES},
search_type => 'scan',
ignore_unavailable => 1,
body => {
size => $self->{PAGINATION},
query => {
filtered => {
filter => {
bool => {
must => [{term => {signature_id => $item->{profileId}}}, {terms => {channel_type_id => $type}}]
}
}
}
}
}
);
As you can see, I'm doing the scroll without passing scroll parameter then as documentation says, the time that scroll is alive is 1 min.
The elasticSearch is a cluster of 3 servers, and the query that ends with that error retrieves a bit more than 5000 docs.
My first solution was to update the life time for scroll to 5 minutes and the error didn't appear.
The question is, as I understand every time I'm calling $scroll->next() the life time off scroll affected is upgraded 1m more, then how is possible to receive those context related errors?
I'm doing something in a bad manner?
Thank you all.
The first thing that comes to mind is that the timer is not updated. Have you checked this? You can do a query every 10 seconds for example and see if at the 6th query it gives you the error ...
Well, a good rule of thumb is inside a ->next() block, don't stay by iteration more than time that you've configured in scroll.
Between each call of ->next() you cannot stay more than that time configured. If you stay more, the scroll may be not be there and the error earch_context_missing_exception will appear.
My solution for this problem was inside next block only store data into array/hash structure and once the scroll process ended work with all data.
The solution of the question example:
# Retrieve scroll
my $scroll = $self->getScrollBySignature($item);
# Retrieve all affected documents ids
my #allDocs;
while (my #docs = $scroll->next(500)) {
push #allDocs, map {$_->{_id}} #docs
}
foreach (#allDocs) {
# Do stuff with doc
}