I just inherited some cakePHP code and I am not very familiar with it (or any other php/serverside language). I need to set the id of the item I am adding to the database to be the value of the last item plus one, originally I did a call like this:
$id = $this->Project->find('count') + 1;
but this seems to add about 8 seconds to my page loading (which seems weird because the database only has about 400 items) but that is another problem. For now I need a faster way to find the id of the last item in the database, is there a way using find to quickly retrieve the last item in a given table?
That's a very bad approach on setting the id.
You do know that, for example, MySQL supports auto-increment for INT-fields and therefore will set the id automatically for you?
The suggested functions getLastInsertId and getInsertId will only work after an insert and not always.
I also can't understand that your call adds 8 seconds to your siteload. If I do such a call on my table (which also has around 400 records) the call itself only needs a few milliseconds. There is no delay the user would notice.
I think there might be a problem with your database-setup as this seems very unlikely.
Also please have a look if your database supports auto-increment (I can't imagine that's not possible) as this would be the easiest way of adding your wanted functionality.
I would try
$id = $this->Project->getLastInsertID();
$id++;
The method can be found in cake/libs/model/model.php in line 2768
As well as on this SO page
Cheers!
If you are looking for the cakePHP3 solution to this you simply use last().
ie:
use Cake\ORM\TableRegistry;
....
$myrecordstable=Tableregistry::get('Myrecords');
$myrecords=$myrecordstable->find()->last();
$lastId = $myrecords->id;
....
Related
I'm developing an app which needs to record a list of a users recent video uploads. Importantly it needs to only remember the last two videos associated with the user so I'm trying to find a way to just keep the last two records in a database.
What I've got so far is the below, which creates a new record correctly, however I then want to delete all records that are older than the previous 2, so I've got the below.
The problem is that this seems to delete ALL records even though, by my understanding, the skip should miss out the two most recent records,
private function saveVideoToUserProfile($userId, $thumb ...)
{
RecentVideos::create([
'user_id'=>$userId,
'thumbnail'=>$thumb,
...
]);
RecentVideos::select('id')->where('user_id', $userId)->orderBy('created_at')->skip(2)->delete();
}
Can anyone see what I'm doing wrong?
Limit and offset do not work with delete, so you can do something like this:
$ids = RecentVideos::select('id')->where('user_id', $userId)->orderByDesc('created_at')->skip(2)->take(10000)->pluck('id');
RecentVideos::whereIn('id', $ids)->delete();
First off, skip() does not skip the x number of recent records, but rather the x number of records from the beginning of the result set. So in order to get your desired result, you need to sort the data in the correct order. orderBy() defaults to ordering ascending, but it accepts a second direction argument. Try orderBy('created_at', 'DESC'). (See the docs on orderBy().)
This is how I would recommend writing the query.
RecentVideos::where('user_id', $userId)->orderBy('created_at', 'DESC')->skip(2)->delete();
My data model has an entity Person with 3 related (1:N) entities Jobs, Tasks and Dates.
My query looks like
var persons = (from x in context.Persons
select new {
PersonId = x.Id,
JobNames = x.Jobs.Select(y => y.Name),
TaskDates = x.Tasks.Select(y => y.Date),
DateInfos = x.Dates.Select(y => y.Info)
}).ToList();
Everything seems to work fine, but the lists JobNames, TaskDates and DateInfos are not all filled.
For example, TaskDates and DateInfos have the correct values, but JobNames stays empty. But when I remove TaskDates from the query, then JobNames is correctly filled.
So it seems that EF can only handle a limited number of these "subqueries"? Is this correct? If so, what is the max. number of these "subqueries" for a single statement? Is there a way to work around these issue without having to make more than one call to the database?
(ps: I'm not entirely sure, but I seem to remember that this query worked in LINQ2SQL - could it be?)
UPDATE
I'm getting crazy about this. I tried to repro the issue from ground up using a fresh, simple project (to post the entire piece of code here, not only an oversimplified example) - and I found I wasn't able to repro it. It still happens within our existing code base (apparently there's more behind this problem, but I cannot share this closed code base, unfortunately).
After hours and hours of playing around I found the weirdest behavior:
It works great when I don't SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED; before calling the LINQ statement
It also works great (independent of the above) when I don't use a .Take() to only get the first X rows
It also works great when I add an additional .Where() statements to cut the the number of rows returned from SQL Server
I didn't find any comprehensible reason why I see this behavior, but I started to look at the SQL: Although EF generates the exact same SQL, the execution plan is different when I use READ UNCOMMITTED. It returns more rows on a specific index in the middle of the execution plan, which curiously ends in less rows returned for the entire SQL statement - which in turn results in the missing data, that is the reason for my question to begin with.
This sounds very confusing and unbelievable, I know, but this is the behavior I see. I don't know what else to do, I don't even know what to google for at this point ;-).
I can fix my problem (just don't use READ UNCOMMITTED), but I have no idea why it occurs and if it is a bug or something I don't know about SQL Server. Maybe there's some "magic max number of allowed results in sub-queries" in SQL Server? At least: As far as I can see, it's not an issue with EF itself.
A little late, but does calling ToList() on each subquery produce the required effect?
var persons = (from x in context.Persons
select new {
PersonId = x.Id,
JobNames = x.Jobs.Select(y => y.Name.ToList()),
TaskDates = x.Tasks.Select(y => y.Date).ToList(),
DateInfos = x.Dates.Select(y => y.Info).ToList()
}).ToList();
I'd like to do an upmerge using LLBLGen without first fetching then saving the entity.
I already found the possibility to update without fetching the entity first, but then I have to know it is already there.
Updating entries would be about as often as inserting a new entry.
Is there a possibility to do this in one step?
Would it make sense to do it in one step?
Facts:
LLBLgen Pro 2.6
SQL Server 2008 R2
.NET 3.5 SP1
I know I'm a little late for this, but As I remember working with LLBLGenPro, it is totally possible and one of its beauties is everithing is possible!
I don't have my samples, but I'm pretty sure you there is a method named UpdateEntitiesDirectly that can be used like this:
// suppose we have Product and Order Entities
using (var daa = new DataAccessAdapter())
{
int numberOfUpdatedEntities =
daa.UpdateEntitiesDirectly(OrderFields.ProductId == 23 && OrderFields.Date > DateTime.Now.AddDays(-2));
}
When using LLBLGenPro we were able to do pretty everything that is possible with an ORM framework, it's just great!
It also has a method to do a batch delete called DeleteEntitiesDirectly that may be usefull in scenarios that you need to delete an etity and replace it with another one.
Hope this is helpful.
I think you can achieve what you're looking for by using EntityCollection. First fetch the entities you want to update by FetchEntityCollection method of DataAccessAdapter then, change anything you want in that collection, insert new entities to it and save it using DataAccessAdapter, SaveCollection method. this way existing entities would be updated and new ones would be inserted to the Database. For example in a product order senario in which you want to manipulate orders of a specified product then you can use something like this:
int productId = 23;
var orders = new EntityCollection<OrderEntity>();
using (DataAccessAdapter daa = new DataAccessAdapter())
{
daa.FetchEntityCollection(orders, new RelationPredicateBucket(OrderFields.ProductId == productId))
foreach(var order in orders)
{
order.State = 1;
}
OrderEntity newOrder = new OrderEntity();
newOrder.ProductId == productId;
newOrder.State = 0;
orders.Add(newOrder);
daa.SaveEntityCollection(orders);
}
As far as I know, this is not possible, and could not be possible.
If you were to just call adapter.Save(entity) on an entity that was not fetched, the framework would assume it was new. If you think about it, how could the framework know whether to emit an UPDATE or an INSERT statement? No matter what, something somewhere would have to query the database to see if the row exists.
It would not be too difficult to create something that did this more or less automatically for single entity (non-recursive) saves. The steps would be something like:
Create a new entity and set it's fields.
Attempt to fetch an entity of the same type using the PK or a unique constraint (there are other options as well, but none as uniform)
If the fetch fails, just save the new entity (INSERT)
If the fetch succeeds, map the fields of the created entity to the fields of the fetched entity.
Save the fetched entity (UPDATE).
I am trying a case where we changed a field name in our entity. we have something like this for example
class Person {
String name; //The original declaration was "String fullName"
}
According to objectify you have to use annonation #AutoLoad(""). This is ok and it works as Google Datastore doesn't delete the data Actually but it makes a new field so this annotation is like a mapping between the old and the new field. No problem when you are reading the whole table.
The problem arises when you apply a filter on your query (Suppose you made 5 objects with old name and 5 with new name). The result of your query depends on whether you used the old variable name or the new one (returns back only 5 but never the 10). It won't fetch both of them and map them. Any Suggestions for this problem? I hope i explained it in a clear way.
Thanks in advance
The simplest straight forward solution. fetch all data with the annonation "AutoLoad()". Then store them again. In this way they will be saved as the new field. The old one doesn't exist anymore or at least it doesn't contain any data anymore. It is like migrating the data from the old name to the new name. Anyone has better suggestions ?
If you've changed the name of your field, you need to load and re-put all your data (using the mapreduce API would be one option here). There's no magic way around this - the data you've stored exists with two different names on disk.
You can use #OldName
http://www.mail-archive.com/google-appengine-java#googlegroups.com/msg05586.html
So, I have an autocomplete dropdown with a list of townships. Initially I just had the 20 or so that we had in the database... but recently, we have noticed that some of our data lies in other counties... even other states. So, the answer to that was buy one of those databases with all towns in the US (yes, I know, geocoding is the answer but due to time constraints we are doing this until we have time for that feature).
So, when we had 20-25 towns the autocomplete worked stellarly... now that there are 80,000 it's not as easy.
As I type I am thinking that the best way to do this is default to this state, then there will be much less. I will add a state selector to the page that defaults to NJ then you can pick another state if need be, this will narrow down the list to < 1000. Though, I may have the same issue? Does anyone know of a work around for an autocomplete with a lot of data?
should I post teh codez of my webservice?
Are you trying to autocomplete after only 1 character is typed? Maybe wait until 2 or more...?
Also, can you just return the top 10 rows, or something?
Sounds like your application is suffocating on the amount of data being returned, and then attempted to be rendered by the browser.
I assume that your database has the proper indexes, and you don't have a performance problem there.
I would limit the results of your service to no more than say 100 results. Users will not look at any more than that any how.
I would also only being retrieving the data from the service once 2 or 3 characters are entered which will further reduce the scope of the query.
Good Luck!
Stupid question maybe, but... have you checked to make sure you have an index on the town name column? I wouldn't think 80K names should be stressing your database...
I think you're on the right track. Use a series of cascading inputs, State -> County -> Township where each succeeding one grabs the potential population based on the value of the preceding one. Each input would validate against its potential population to avoid spurious inputs. I would suggest caching the intermediate results and querying against them for the autocomplete instead of going all the way back to the database each time.
If you have control of the underlying SQL, you may want to try several "UNION" queries instead of one query with several "OR like" lines in its where clause.
Check out this article on optimizing SQL.
I'd just limit the SQL query with a TOP clause. I also like using a "less than" instead of a like:
select top 10 name from cities where #partialname < name order by name;
that "Ce" will give you "Cedar Grove" and "Cedar Knolls" but also "Chatham" & "Cherry Hill" so you always get ten.
In LINQ:
var q = (from c in db.Cities
where partialname < c.Name
orderby c.Name
select c.Name).Take(10);