[Laravel pit avoidance notes] Laravel error reporting problem 42S01 420004 42S22] etc...

                                                                                         

The following column will introduce you to laravel error reporting issues 42S01 420004 42S22], etc... I hope it will be helpful to friends who need it!

laravel pitfall avoidance notes

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1.Laravel 5.4: Specified key was too long error

Cause: Starting from LV 5.4, the default character set of the database is utf8mb4 (including support for emojis). If you are using MySQL v5.7.7 or higher, no modifications are required. Children's shoes that use earlier versions of MySQL databases (including MariaDB) can be modified like this. Modify the file /project/app/Providers/AppServiceProvider.php

use Illuminate\Support\Facades\Schema; // 注意要引入命名空间

 public function boot()
    {
        Schema::defaultStringLength(191); // 针对 早期 mysql 数据迁移
    }

and then re-use the migration command:

php artisan migrate

2.SQLSTATE[42S01]: Base table or view already exists: 1050

The table already exists when migrating data,Solution:

Delete the existing table and then migrate it again.

3.PDOException::("SQLSTATE[42000]: Syntax error or access violation: 1067 Invalid default value for 'published_at'")

Modification method one: vim config/database.php

'mysql' => [
     'driver' => 'mysql',.... ...
     'prefix' => '', 
     'strict' => true, // 修改这里
     'engine' => null,
 ],

Modify to:

• 'mysql' => [
       'driver' => 'mysql',.... ...
       'prefix' => '', 
       'strict' => false, // 修改这里
       'engine' => null,
   ],

Set the time that can be empty Stamp:

$table->nullableTimestamps()

Set the default timestamp

$table->timestamps('created_at');// 会生成created_at\updated_at字段

##4.PDOException::(“SQLSTATE[42S22]: Column not found : 1054 Unknown column 'created_at' in 'field list'")

This problem is due to the fact that the default timestamp field is not set during table migration, but the factory method is used to generate seed data. You can modify

public function up()
    {   
      Schema::create('posts', function (Blueprint $table) {
      $table->increments('id');
      $table->string('slug')->unique();
      $table->string('title');
      $table->text('content');
      $table->timestamps(); // 添加这行
      }); }

Repeat make:migration

To be precise, this is not a pitfall, because this operation It only needs to be executed once

But for novices, it may be repeated multiple times unintentionally, and no error will be reported when making:migration;

And there is a problem when executing migration Here it comes:

The solution is to delete or modify the schema name of the same table.

##5.php artisan db:seed table name becomes plural and singular

This may be related to Chinglish , foreigners are accustomed to writing table names as plurals, so they simply default to the table name corresponding to the Model as the plural form of the English word Therefore, the $table attribute must be rewritten in the model, such as: protected $ table='student';

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