Laravel query relationship based on name not id - php

Question

Hi I am new laravel and struggling a bit on understanding how to query relationships. I am trying to make a basic restful api in laravel and have 3 models
class Book extends Model
{
public function author()
{
return $this->belongsTo(Author::class);
}
public function categories()
{
return $this->belongsToMany('App\Category', 'category_book')
->withTimestamps();
}
}
class Author extends Model
{
public function books(){
return $this->hasMany(Book::class);
}
}
class Category extends Model
{
public function books()
{
return $this->belongsToMany('App\Book', 'category_book')
->withTimestamps();
}
}
Table migrations:
Schema::create('books', function (Blueprint $table) {
$table->engine = "InnoDB";
$table->increments('id');
$table->string('ISBN', 32);
$table->string('title');
$table->integer('author_id')->unsigned();
$table->float('price')->default(0);
$table->timestamps();
});
Schema::create('authors', function (Blueprint $table) {
$table->engine = "InnoDB";
$table->bigIncrements('id');
$table->string('name');
$table->string('surname');
$table->timestamps();
});
Schema::create('categories', function (Blueprint $table) {
$table->engine = "InnoDB";
$table->bigIncrements('id');
$table->string('name');
$table->timestamps();
});
Schema::create('category_book', function (Blueprint $table) {
$table->bigIncrements('id');
$table->integer('category_id')->unsigned();
//$table->foreign('category_id')->references('id')->on('categories')->onDelete('cascade');
$table->integer('book_id')->unsigned();
//$table->foreign('book_id')->references('id')->on('books')->onDelete('cascade');
$table->timestamps();
});
books is the main table and author has a one to many relationship with books. Category has a many to many relationship with books as a book can be in more than one category.
The books table has an author_id field to link it to the authors table. There is also a pivot table called category_books that contains category_id and book_id to link books to categories
But how do I query books so that it returns only books based on the authors name ?
I would also like to do the same thing based on the category name?
I my books controller i have the following but not sure how to do it correctly
public function index(request $request, Author $author, Category $category)
{
$author = $request->author;
$books = Book::find()->author()->where('name', $author);
$books = Book::with(['categories'])->where('name', $category);
return response()->json($books, 200);
}

Answer 1

By author:
$books = App\Book::whereHas('author', function ($query) use ($authorName) {
$query->where('name', $authorName);
})->get();
By category:
$books = App\Book::whereHas('categories', function ($query) use ($categoryName) {
$query->where('name', $categoryName);
})->get();
whereHas allows you to perform where queries on the specified relationship
Together:
$books = App\Book::whereHas('author', function ($query) use ($authorName) {
$query->where('name', $authorName);
})->whereHas('categories', function ($query) use ($categoryName) {
$query->where('name', $categoryName);
})->get();

Answer 2

To filter both author and book at the same query you may use both queries made by gbalduzzi combined:
$books = App\Book::whereHas('author', function ($query) use ($authorName) {
$query->where('name', $authorName);
})->whereHas('categories', function ($query) use ($categoryName) {
$query->where('name', $categoryName);
})->get();