使用DB :: raw表达式的带有POINT/POLYGON等的Laravel模型 [英] Laravel model with POINT/POLYGON etc. using DB::raw expressions

问题描述

我有一些使用地理空间字段的模型，例如POINT，POLYGON或MULTIPOLYGON.我想告诉我的模型以一种特殊的方式处理这些属性，以使我获得所需的模型属性集.

I have some models that use geospatial fields like POINT, POLYGON or MULTIPOLYGON. I would like to tell my model to process these attributes in a special way, for me to get the desired model attributes set.

示例: 每个常规Model::find()或其他Eloquent方法都应在存储数据库值之前或之后应用一些自定义代码.

Example: Every regular Model::find() or other Eloquent method should apply some custom code before storing or after retrieving a database value.

$area->surface是MySQL中的POLYGON字段，但是在我的模型类中，我想将$area->surfare作为点数组处理.

$area->surface is a POLYGON field in MySQL, but in my model class I would like to handle $area->surfare as an array of points.

在SELECT上，我想1)使用原始表达式获取值以获取该值的文本表示形式，2)通过一些自定义PHP代码将WKT字符串转换为数组.

On SELECT I would therefore like to 1) fetch the value using a raw expression to get a text representation of the value, and 2) go through some custom PHP code to convert the WKT string into an array.

在INSERT/UPDATE上，我想获取属性值(一个数组)，然后1)将其转换为WKT字符串，然后2)使用存储该值的DB raw语句将其写入数据库.

On INSERT/UPDATE I would like to take the attribute value (an array) and 1) convert it into a WKT string, whereafter 2) it's written to the databse using a DB raw statement that stores the value.

我想将此设置为基于字段的方式，而不是为每个字段设置特殊的获取/设置功能，而不是在控制器中设置-因为我有很多地理空间字段.

I'd like to set this on a field-basis, not as special get/set functions for each field, and not in the controllers - because I have many geosptial fields.

在Laravel中有实现此目标的方法吗?

(同一问题的一个更抽象的版本，是我如何创建用于处理实际SQL查询的属性值的代码，而不仅仅是通过增减器和访问器进行基于值的操作)

更新: 深入研究Laravel Doc和API，我发现也许Eloquent::newQuery()方法是我需要操纵的?不论SELECT，INSERT或UPDATE，该查询都将用于任何查询吗?

UPDATE: Looking deeper into the Laravel Doc and API, I found that maybe the Eloquent::newQuery() method is what I need to manipulate? Would that be used for any query regardless if SELECT, INSERT or UPDATE?

推荐答案

我们现在通过扩展以下功能来对所有模型进行通用解决:

We have now solved this generically for all models by extending our base model with the following functionaly:

• 我们定义了一个保存几何数据的属性数组.
• 如果我们希望将其自动加载为文本，则决定是否基于模型.
• 我们更改了默认查询生成器，以从数据库中选择几何属性作为文本.

以下是我们现在使用的基本模型的摘录:

Here is an excerpt from the base model we now use:

/**
 * The attributes that hold geometrical data.
 *
 * @var array
 */
protected $geometry = array();

/**
 * Select geometrical attributes as text from database.
 *
 * @var bool
 */
protected $geometryAsText = false;

/**
 * Get a new query builder for the model's table.
 * Manipulate in case we need to convert geometrical fields to text.
 *
 * @param  bool  $excludeDeleted
 * @return \Illuminate\Database\Eloquent\Builder
 */
public function newQuery($excludeDeleted = true)
{
    if (!empty($this->geometry) && $this->geometryAsText === true)
    {
        $raw = '';
        foreach ($this->geometry as $column)
        {
            $raw .= 'AsText(`' . $this->table . '`.`' . $column . '`) as `' . $column . '`, ';
        }
        $raw = substr($raw, 0, -2);
        return parent::newQuery($excludeDeleted)->addSelect('*', DB::raw($raw));
    }
    return parent::newQuery($excludeDeleted);
}

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