I am porting my code from CodeIgniter to Laravel. and have some question regarding the query builder.
In codeigniter, I can just add where clause to the active record object, as I initialize each property in a class like
$this->db->where('xxxx','bbbb');
in one property initialize function, and
$this->db->where('yyyy','aaaa');
in another property function, and it will all chain up until i fire off the query. But this doesn't seem to be the case of Laravel.
Here is what I do in laravel in each property initialize function
DB::table($this->table)->where('xxxx','bbbb');
DB::table($this->table)->where('yyyy','aaa');
and when a actual method is call from outside, it runs
DB:table($this->table)->get();
but this gives me a SELECT * FROM TABLENAME without anywhere clause. So what am I doing wrong here :x or I just shouldn't treat laravel same as codeigniter and think of something totally different to handle this kind of dynamic where clause?
Also in codeigniter, you can set a section of the query to cache, so even after you fire off the query , those section retains for next query, usually the where clause. Is there a similar function in Laravel? Thank you!
You can assign your current workings to a variable, and build upon that, let me show you an example based on your example:
Instead of this
DB::table($this->table)->where('xxxx','bbbb');
DB::table($this->table)->where('yyyy','aaa');
Try this...
$query = DB::table($this->table)->where('xxxx','bbbb');
$query->where('yyyy','aaa');
$results = $query->get();
I just shouldn't treat laravel same as codeigniter and think of something totally different to handle this kind of dynamic where clause?
This is not dynamic where clause.
and please, make a habit of reading the documentation.
From the docs of Fluent query builder
$users = DB::table('users')->where('votes', '>', 100)->get();
you can set a section of the query to cache, so even after you fire off the query , those section retains for next query, usually the where clause. Is there a similar function in Laravel?
$users = DB::table('users')->remember(10)->get();
Next time, just open up the docs. they contain all this.
Related
when I want to get data from a database in native PHP I use queries but in laravel, you don't write queries you use their model and their functions to get the data for example:
ex::where('name','test')->get();
in native PHP:
select * from ex where name='test'
and my issue is I don't know how to use and like this query:
select * from ex where name='test' and id='5'
I searched and looked thru the documentation but no answer was found.
Just put another where, its really simple just put it like this
ex::where('name', 'test')->where('id', 5)->get();
//or if you want directly the instance and not a collection
ex::where('name', 'test')->find(5);
If you want to use the OR operator you can also do something like this
ex::where('name', 'test')->orWhere('id', 5)->get();
More in documentations
There is no 'AND' with where in Laravel Eloquent.
You have to write another 'where' with the required condition.
Another way is: run queries using the DB facade. The DB facade provides methods for each type of query: select, update, insert, delete, and statement.
Ex. DB::statement("UPDATE teachers SET price = ".$price." where id=".$id." AND status='A'");
Do not forget to use DB
i hope you are having a good time. i am learning laravel and the inscuctor talked about when you load relationships in laravel, like so
public function timeline()
{
$ids = $this->follows()->pluck('id');
$ids->push($this->id);
return Tweet::whereIn('user_id', $ids)->latest()->get();
}
and i have a follows relationship in my model, and he talked about this line
$ids = $this->follows()->pluck('id');
being better for performance than this line
$ids = $this->follows->pluck('id');
my question is, how does laravel pluck the ids in the first case, and how it queries the database
i hope im making sense, thanks for your time, and answer.
the following one executes a select query on database
$this->follows()->pluck('id');
the follows() returns a query builder (which is a not yet executed sql statement) and then on the result select the id column and returns a collection of ids
you can see the query by dumping the query builder by $this->follows()->dd()
Whereas in the second option
$this->follows->pluck('id')
up until $this->follows laravel executes a query and returns all the records as a collection instance, You will be able to see all the attributes on each of the records. And then ->pluck('id') is getting executed on the laravel collection class, which will do an operation I assume similar to the array_column function does and returns only the id column.
as you can easily see in the second operation the whole data set was retrieved first from the DB and then selected the required attribute/column (2 distinct and heavy operations). Where as in the first option we directly told eloquent to select only the required column, which is only one lighter operation compared to the second option.
My application dynamically builds and runs complex queries to generate reports. In some instances I need to get multiple, somewhat arbitrary date ranges, with all other parameters the same.
So my code builds the query with a bunch of joins, wheres, sorts, limits etc and then runs the query. What I then want to do is jump into the Builder object and change the where clauses which define the date range to be queried.
So far, I have made it so that the date range is setup before any other wheres and then tried to manually change the value in the relevant attribute of the wheres array. Like this;
$this->data_qry->wheres[0]['value'] = $new_from_date;
$this->data_qry->wheres[1]['value'] = $new_to_date;
Then I do (having already done it once already)
$this->data_qry->get();
Doesn't work though. The query just runs with the original date range. Even if my way worked, I still wouldn't like it though as it seems to be shot through with a precarious dependence (some sort of coupling?). Ie; if the date wheres aren't set up first then it all falls apart.
I could set the whole query up again from scratch, just with a different date range, but that seems ott as everything else in the query needs to be the same as the previous time it was used.
Any ideas for how to achieve this in the correct / neatest way are very welcome.
Thanks,
Geoff
You can use clone to duplicate the query and then run it with different where statements. First, build the query without the from-to constraints, then do something like this:
$query1 = $this->data_qry;
$query2 = clone $query1;
$result1 = $query1->where('from', $from1)->where('to', $to1)->get();
$result2 = $query2->where('from', $from2)->where('to', $to2)->get();
The suggestion from #lukasgeiter using clone is definitely the way to go; the reason is that an Eloquent\Builder object contains an internal reference to a Query\Builder that needs to be duplicated.
To keep the flow of your app and get back to a more functional style, you can use Laravel's with() helper, which simply returns the object passed in:
$result1 = with(clone $this->data_qry)->where('from', $from1)->where('to', $to1)->get();
$result2 = with(clone $this->data_qry)->where('from', $from2)->where('to', $to2)->get();
For the people who want a simpler and shorter syntax, you can daisy chain the clone() method on the query builder.
$result1 = $this->data_qry->clone()->where('from', $from1)->where('to', $to1)->get();
$result2 = $this->data_qry->clone()->where('from', $from2)->where('to', $to2)->get();
is there a way for Eloquent/raw queries to execute a function before a query is fired? It would also be nice if I could extend the functionality to pass a parameter if the function should be run before or not. Depending on the outcome of the function (true/false) the query shouldn't be executed.
I would be nice to use the principal of "DB::listen", but I'm not sure if I can stop or run the query from within this function.
The reason for this is that I would like to build a little data warehouse myself for permanently saving results to a warehouse (db) and not query a huge database all the time.
The method I'm would like to use is to create a hash of a query, check if the hash exists in the warehouse. If it exists, then the value is returned. If not the query is executed and the output is saved together with the hash into the warehouse.
Any ideas?
///// EDIT /////
I should clarify, that I would like to access the queries and update the value if the calculated value needs to be updated. i.e.: Number of cars in december: While I'm in december, I need to keep updating the value every so often. So I store the executed query in the db and just retrieve it, run it and then update the value.
//// EDIT 2 /////
Github: https://github.com/khwerhahn/datawarehouselibrary/blob/master/DataWareHouseLib.php
What I would like to achieve is to hook into Laravels query/Eloquent logic and use the data warehouse logic in the background.
Maybe something like this:
$invalid_until = '2014-12-31 23:59:59'; // date until query needs to be updated every ten minutes
$cars = Cars::where('sales_month', '=', 12)->dw($invalid_until)->get();
If the dw($date_parameter) is added I would like Laravel to execute the data warehouse logic in the background and if found in the db then not execute the query again.
You don't need to use events to accomplish this. From the 4.2 docs:
Caching Queries
You may easily cache the results of a query using the remember method:
$users = DB::table('users')->remember(10)->get();
In this example, the results of the query will be cached for ten
minutes. While the results are cached, the query will not be run
against the database, and the results will be loaded from the default
cache driver specified for your application.
http://laravel.com/docs/4.2/queries#caching-queries
You can also use this for Eloquent objects,
eg: User::where($condition)->remember(60)->get()
I get what you're trying to do, but as I view it (I might not still be getting it right, though) you still can get away with using rememberForever() (if you don't want a specific time limit)
So, let's pretend you have a Cars table.
$cars = Cars::where('sales_month', '=', 12)->rememberForever()->get();
To work around the problem of deleting the cache, you can assign a key to the caching method, and then retrievit by that key. Now, the above query becomes:
$cars = Cars::where('sales_month', '=', 12)->rememberForever('cars')->get();
Every time you run that query you will be getting the same results, first time from the DB, all the others from the cache.
Now you say you're going to update the table, and you want to reset the cache, right?
So, run your update, then forget() the Cache with the cars index:
// Update query
Cache::forget('cars');
Your next call to the Cars query will issue a new resultset, and it will be cached. In case you're wondering, the remember() and rememberForever() are methods of the QueryBuilder class that use the same Cache class you can see in the docs in its own section.
Alternatively, in fact, you could also use the Cache class directly (it gives you a better control):
if (null == $cars= Cache::get('cars')) {
$cars = Cars::where('sales_month', '=', 12)->get();
Cache::forever('cars', $cars);
}
By overriding the method runSelect exsists in Illuminate\Database\Query\Builder that runs in every select query in Laravel.
see this package:
https://github.com/TheGeekyM/caching-queries
I want to group data by year and month of a date column using doctrine.
It currently uses the query builder to produce the statement which is working fine apart from the grouping.
I have installed the Month and Year custom functions from the Doctrine Extensions pack, however, I cannot do the following:
$qb->add('groupBy', 'MONTH(i.instdate)');
I get an Error: Cannot group by undefined identification variable message.
Is this possible with the query builder?
If not can I add DQL to a query builder result? What is the best way to do this?
I don't want to change the whole system to DQL as it is a query built from form options on the fly, so that would be a major change.
There is a workaround that you can use if you can add your custom function to your select clause. You can group by an alias of a custom function result that is in your select clause.
This would look like this
$qb->select('MONTH(i.instdate) as myMonth'....);
$qb->groupBy('myMonth');
It appears that grouping by functions is not possible in the Doctrine version I am using.
It is available in later versions.
I decided to use SQL statments when this was required instead, as changing to a different version of Doctrine, inside ZF this close to a project completion would be too much.