Populating parameters with default value using relationships in Laravel 5.2 - php

Question

Okay, so I have a question. I'm programming a really complex report and the interface uses Laravel 5.2. Now the thing is that, depending on certain conditions, the user does not always need all parameters to be filled. However, for simplicity purposes, I made it so that the report always receives the complete set of parameters no matter what. So I have three tables:
tblReportParam
ID
ParamName
DefaultValue
tblReportParamValue
ParamID
ReportID
Value
tblReport
ID
UserName
Now, I have a solution that works, but for some reason, it just feels like I should be able to make better use of models and relationships. I basically have just my models and controllers and solved the whole thing using SQL.
It feels somewhat close to this but not quite. So basically, you need to always load/save all parameters. If parameter x is actually defined by the user then you use his definition otherwise you go with the default defined in tblReportParam. Anyone has any idea how to do this?
EDIT:
Okay, so I checked Eddy's answer and tried to work it in our system, but another colleague of mine started implementing a many-to-many relationship between the tblReport and the tblReportParam table with the tblReportParamValue acting as the pivot so I'm having some difficulty adapting this solution for our system. Here's the two models:
class ReportParam extends Model
{
/**
* The database table used by the model.
*
* #var string
*/
protected $table = 'tblReportParam';
protected $primaryKey = 'ID';
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $fillable = ['ID', 'NomParam', 'DefaultValue'];
public function renourapports()
{
return $this->belongsToMany('App\Report');
}
}
class Report extends Model
{
/**
* The database table used by the model.
*
* #var string
*/
protected $table = 'tblReport';
protected $primaryKey = 'ID';
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $fillable = ['ID', 'NoEmploye', 'NoClient', 'NoPolice', 'DateCreation', 'DateModification', 'runable', 'DernierEditeur'];
public $timestamps = false;
public function params()
{
return $this->belongsToMany('App\ReportParam ', 'tblReportParamValue', 'ReportID', 'ParamID')->withPivot('Valeur');
}
}
Now this actually is a pretty neat solution, but it only works if the parameter is actually in the pivot table (i.e. the relationship actually exists). What we want is that for the parameters that aren't in the pivot table, we simply want their default value. Can Eddy's solution work in this case?

Answer 1

Using Eloquent models
class ReportParam extends Model
{
public function paramValue() {
return $this->hasOne('App\ReportParamValue', 'ParamID');
}
public function getDefaultValueAttribute($value) {
if ( $this->paramValue ) return $this->paramValue->Value; //relationship exists
return $this->DefaultValue;
}
}
$reportParam->value; // return the relationship value or the default value;
UPDATE
Now that tblReportParamValue is a pivot table you should redefine your relationships. In ReportParam model add
public function reports() {
return $this->belongsToMany('App\Report', 'tblReportParamValue', 'ParamID', 'ReportID')->withPivot('Value');
}
And in Report model, defined the opposite
public function params() {
return $this->belongsToMany('App\ReportParam', 'tblReportParamValue', 'ReportID', 'ParamID')->withPivot('Value');
}
Now getting the default value from ReportParam becomes too complicated because it will one ReportParam has Many Reports. So doing $reportParam->reports() will bring back every single report that uses that paramID in the pivot table. Therefore looking for a value would mean going through all the reports. We could avoid that by changind the function definition.
public function getDefaultValue($reportID) {
$reportValue = $this->reports()->wherePivot('ReportID', $reportID)->first();
return $reportValue ? $this->reportValue->Value : $this->DefaultValue;
}
//In Controller
$report = Report::find(1);
$reportParam = ReportParam::find(1);
$reportParam->getDefaultValue($report->ID);
Ok I think this might work. If it doesnt, I am really sorry, I don't know any better.