entity framework - Linq GroupJoin (join...into) results in INNER JOIN? -


i referencing accepted answer question: linq sql multiple tables left outer join

in example, need of person records regardless if there matching staff record.

i using following query (simplified illustation's sake):

var result = person in context.person                      join staffq in context.staff                          on person.staffid equals staffq.id staffstaffidgroup                      staff in staffstaffidgroup.defaultifempty()                      select new personmodel()                      {                          id = person.id,                          fname = person.fname,                          lname = person.lname,                          sex = person.sex,                          username = staff != null ? staff.username : ""                      };

however, contrary expectations, query results in following sql inner join, eliminates records need in the result set.

select  [extent1].[id] [id],  [extent1].[fname] [fname],  [extent1].[lname] [lname],  [extent1].[sex] [sex],  [extent2].[username] [username]  [dbo].[person] [extent1] inner join [dbo].[staff] [extent2] on [extent1].[staffid] = [extent2].[id]

i thought groupjoin (or join...into) supposed around this? know must have made dumb mistake here, can't see it.

in general query should generate left outer join.

but remember, ef, , has additional information coming model. in case looks staffid property of person enforced fk constraint stuff, ef knows there corresponding record in staff table, hence ignoring left outer join construct , generates inner join instead.

again, model (properties, whether required or not, relationships - required or not etc.) allows ef perform similar smart decisons , optimizations.


Comments

Post a Comment

Popular posts from this blog

What is happening when Matlab is starting a "parallel pool"? -

running parallel cpu processes in matlab starts command parpool() according documentation , function: [creates] special job on pool of workers, , [connects] matlab client parallel pool. this function takes bit of time execute, on order of 30 seconds. in other multi-cpu paradigms openmp, parallel execution seems totally transparent -- i've never noticed behavior analogous matlab (granted i'm not experienced parallel programming). so, happening between time parpool() called , when finishes executing? takes long? parallel computing toolbox enables run matlab code in parallel using several different paradigms (e.g. jobs , tasks, parfor , spmd , parfeval , batch processing), , run either locally (parallelised across cores in local machine) or remotely (parallelised across machines in cluster - either 1 own, or 1 in cloud). in of these cases, code run on matlab workers , copies of matlab without interactive desktop. if you're intending run on remo...
Read more

angular - DownloadURL return null in below code -

when change file updated in firebase storage when try downloadurl show null. filechange(event: any) { const imagefolder: string = this.employee.id; const filelist: filelist = event.target.files; const file: file = filelist[0]; const storageref = firebase.storage().ref().child(`${imagefolder}/profile.jpg`).put(file); console.log(storageref.snapshot.downloadurl); } the put() asynchronous. if want url after file uploaded have this: firebase.storage().ref().child(`${imagefolder}/profile.jpg`).put(file).then((snapshot) => { storageref = snapshot.downloadurl: console.log(snapshot.downloadurl); });
Read more

php - Cannot override Laravel Spark authentication with own implementation -

during login process of laravel spark need request token of remote api. api stores exact same users , passwords laravel spark application. therefore need username , non hashed password of user during authentication process. i thought overriding authenticated method solution problem. in routes/web.php override post /login endpoint , pointing endpoint own logincontroller: <?php namespace app\http\controllers\auth; use illuminate\support\facades\log; use illuminate\http\request; use laravel\spark\http\controllers\auth\logincontroller sparklogincontroller; class logincontroller extends sparklogincontroller { /** * create new login controller instance. * * @return void */ public function __construct() { parent::__construct(); } /** * handle successful authentication attempt. * * @param request $request * @param \illuminate\contracts\auth\authenticatable $user * @return response */ public fu...
Read more