How to Merge Two Eloquent Collections

Question

I have a questions table and a tags table  I want to fetch all questions from tags of a given question  So  for example  I may have the tags  Travel    Trains  and  Culture  attached to a given question  I want to be able to fetch all questions for those three tags  The tricky  so it seems  is that questions and tags relationship is a many-to-many defined in Eloquent as belongsToMany   I thought about trying to merge the questions Collections as below   foreach   question- gt tags as  tag        if   isset  related              related    tag- gt questions        else            related- gt merge  tag- gt questions             It doesn t seem to work though  Doesn t seem to merge anything  Am I attempting this correctly  Also  is there perhaps a better way to fetch a row of rows in a many-to-many relationship in Eloquent

User · Answer

Creating a new base collection for each eloquent collection the merge works for me.

$foo = collect(Foo::all());
$bar = collect(Bar::all());
$merged = $foo->merge($bar);

In this case don't have conflits by its primary keys.

User · Answer

The merge   method on the Collection does not modify the collection on which it was called  It returns a new collection with the new data merged in  You would need    related    related- gt merge  tag- gt questions     However  I think you re tackling the problem from the wrong angle   Since you re looking for questions that meet a certain criteria  it would probably be easier to query in that manner  The has   and whereHas   methods are used to generate a query based on the existence of a related record   If you were just looking for questions that have any tag  you would use the has   method  Since you re looking for questions with a specific tag  you would use the whereHas   to add the condition   So  if you want all the questions that have at least one tag with either  Travel    Trains   or  Culture   your query would look like    questions   Question  whereHas  tags   function  q         q- gt whereIn  name     Travel    Trains    Culture       - gt get      If you wanted all questions that had all three of those tags  your query would look like    questions   Question  whereHas  tags   function  q         q- gt where  name    Travel      - gt whereHas  tags   function  q         q- gt where  name    Trains      - gt whereHas  tags   function  q         q- gt where  name    Culture      - gt get

User · Answer

All do not work for me on eloquent collections  laravel eloquent collections use the key from the items I think which causes merging issues  you need to get the first collection back as an array  put that into a fresh collection and then push the others into the new collection   public function getFixturesAttribute          fixtures   collect   this- gt homeFixtures- gt all           this- gt awayFixtures- gt each  function   fixture   use    fixtures              fixtures- gt push   fixture                return  fixtures

User · Answer

users   User  all     associates   Associate  all      userAndAssociate    users- gt merge  associates

User · Answer

The merge method returns the merged collection  it doesn t mutate the original collection  thus you need to do the following   original   new Collection   foo       latest   new Collection   bar       merged    original- gt merge  latest      Contains foo and bar    Applying the example to your code   related   new Collection     foreach   question- gt tags as  tag         related    related- gt merge  tag- gt questions

User · Answer

Merge two different eloquent collections into one and some objects happen to have the same id  one will overwrite the other  Use push   method instead or rethink your approach to the problem to avoid that  Refer to web

[php] How to Merge Two Eloquent Collections?

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