How to use where condition in laravel eloquent - laravel

Question

I am using laravel eloquent. I have fetched data from two table using eloquent.
I have post table and chat table. For post table I have model Post.php and for chat table I have model Chat.php. Here is the the eloquent relation I have created to fetch chat for individual post for a user.
in Post.php
public function TeamMessage()
{
return $this->hasMany('App\Chat','post_id');
}
And in Chat.php
public function ChatRelation()
{
return $this->belongsTo('App\Post');
}
it is working perfect. But this relation fetch all messages for a specific post. I want to fetch all unread message from chat table. I have a column named unread in chat table.
Now my question is how I can fetch only unread message for a specific post.

Answer 1

While the other answers all work, they either depend on scopes (which are very useful in many circumstances) or on you having already instantiated an instance of $post, which doesn't let you eager load multiple posts with their messages.
The dynamic solution is this, which will let you fetch either 1 or more posts and eager load their messages with subquery:
$posts = Post::with(['TeamMessage' => function ($query) {
$query->where('unread', true); // This part applies to the TeamMessage query
}])->get();
See in documentation
Edit:
If you, however, want to filter the posts, to only show those that have unread messages, you need to use whereHas instead of with:
$posts = Post::whereHas(['TeamMessage' => function ($query) {
$query->where('unread', true); // This part applies to the TeamMessage query
}])->get();
More in the documentation.
You can also chain whereHas(...) with with(...).

Answer 2

For querying relationships, you have to call them as functions instead of properties, like this:
$unreadPosts = $post->TeamMessage()->where('unread', true)->get();
For more information on this you can take a look at the docs.

Answer 3

You need to create a local scope on your model, information on local scopes can be found here: https://laravel.com/docs/5.6/eloquent#local-scopes
public function scopeUnread($query)
{
return $query->where('unread', 1);
}
Then in your controller/view
$unread = $yourmodel->unread()

Answer 4

First I would change your relation names to the name of the entity in lower case:
in Post.php
public function chats()
{
return $this->hasMany('App\Chat','post_id');
}
And in Chat.php
public function post()
{
return $this->belongsTo('App\Post');
}
public function scopeUnread($query)
{
return $query->where('unread', 1);
}
Then you can use
$post->chats()->unread()->get();