Laravel - Multiple primary key - php

Question

I'm new on Laravel framework, I try too create table with 2 foreign key and I want they become primary in this table. But I have an error when I write php artisan migrate
SQLSTATE[42000]: Syntax error or access violation: 1068 Multiple primary ke
y defined (SQL: alter table doc_tag add primary key doc_tag_id_tag_primar
y(id_tag)
Schema::create('doc_tag', function(Blueprint $table)
{
$table->integer('id_doc')->unsigned();
$table->primary('id_doc');
$table->foreign('id_doc')
->references('id')
->on('doc');
$table->integer('id_tag')->unsigned();
$table->primary('id_tag');
$table->foreign('id_tag')
->references('id')
->on('tag');
});
I know the SQL code which is : (But I do not really know how to translate this SQL code in Laravel)
CREATE TABLE IF NOT EXISTS `Doc_project`.`document_has_Tags` (
`document_id_document` INT NOT NULL,
`Tags_id_Tag` INT NOT NULL,
PRIMARY KEY (`document_id_document`, `Tags_id_Tag`),
INDEX `fk_document_has_Tags_Tags1_idx` (`Tags_id_Tag` ASC),
INDEX `fk_document_has_Tags_document1_idx` (`document_id_document` ASC),
CONSTRAINT `fk_document_has_Tags_document1`
FOREIGN KEY (`document_id_document`)
REFERENCES `Doc_project`.`document` (`id_document`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_document_has_Tags_Tags1`
FOREIGN KEY (`Tags_id_Tag`)
REFERENCES `Doc_project`.`Tags` (`id_Tag`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
It's an N:N relation
Someone have an idea ?

Answer 1

Eloquent doesn't support multiple primary keys, but if you still want it, send an array to your primary(...).
So in your case:
Schema::create('doc_tag', function(Blueprint $table)
{
$table->integer('id_doc')->unsigned();
$table->integer('id_tag')->unsigned();
$table->primary(['id_tag', 'id_doc']);
$table->foreign('id_doc')
->references('id')
->on('doc');
$table->foreign('id_tag')
->references('id')
->on('tag');
});

Answer 2

If you want to create primary key on 2 or more columns you should use:
$table->primary(['id_doc','id_tag']);