Foreign Key Laravel 8 foreignId + constrained - 无法添加或更新子行：外键约束失败

Question

我有 'categories_blogs' 和 'blogs' 迁移。

我正在使用新的 foreignId，受 bigint 约束，在 'blogs' table:

中添加一行时出现以下错误

无法添加或更新子行：外键约束失败 (test.blogs, CONSTRAINT blogs_category_id_foreign FOREIGN KEY (category_id) REFERENCES categories_blog (id))

    Schema::dropIfExists('categories_blogs');

    Schema::create('categories_blogs', function (Blueprint $table) {
        $table->id();
        $table->string('category_name');
        $table->timestamps();
    });

   Schema::create('blogs', function (Blueprint $table) {
            $table->id();
            $table->foreignId('category_id')->constrained('categories_blog');
            $table->string('slug');
            $table->string('title');
            $table->timestamps();
  });

没有 bigint 和旧的外键方式，工作正常：

Schema::dropIfExists('categories_blogs');

Schema::create('categories_blogs', function (Blueprint $table) {
    $table->increments('id');
    $table->string('category_name');
    $table->timestamps();
});

Schema::create('blogs', function (Blueprint $table) {
    $table->increments('id');
    $table->integer('category_id')->unsigned();
    $table->foreign('category_id')->references('id')->on('blogs')->onDelete('cascade');
    $table->string('slug');
    $table->string('title');
    $table->string('description');
    $table->longtext('content');
    $table->timestamps();
});

我该如何解决？谢谢！

Answer 1

根据documentation，constrained()方法将使用约定来确定table名称：

$table->foreignId('category_id')->constrained('categories_blogs');

Foreign Key Laravel 8 foreignId + constrained - 无法添加或更新子行：外键约束失败

Foreign Key Laravel 8 foreignId + constrained - Cannot add or update a child row: a foreign key constraint fails

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