Discuss serial model type conversion in ThinkPHP5 development

With the rapid development of the Internet, the development of websites and applications is becoming more and more common. PHP is one of the most popular programming languages ​​in these development fields. In PHP development, the ThinkPHP framework is a popular tool that provides out-of-the-box functionality to make development more efficient.

In this article, we will explore serial model type conversion in ThinkPHP5 development.

What is type conversion?

In PHP, type conversion refers to the process of converting one data type to another data type. We often need to perform type conversion, such as converting a string to an integer or an integer to a floating point number. PHP provides built-in functions to implement these conversions.

In the ThinkPHP5 model, type conversion is very important. The model is part of the ORM (Object-Relational Mapping), which allows us to map database tables to PHP classes and map class attributes to table columns.

Model type conversion refers to forced type conversion of data in the model. Many times, the data types in the database tables are different from the data types we want to use in PHP. For example, a date in a database will be stored as a string, but we usually need to convert it to PHP's DateTime object. At this point, we need to perform type conversion in the model.

Type conversion in ThinkPHP5

In ThinkPHP5, we can use the protected $type attribute to define data types. This property allows us to type cast data directly in the model. For example, if the data type in the database is string, but we need to convert it to an integer, we can use the following code:

protected $type = [
    'price' => 'integer',
];

In this example, we convert the data of the column named price in the database table The type is defined as integer. When reading data from data, it is automatically converted to an integer.

When we insert data into the database, type conversion can also be performed. For example, let's say we have a field called created_at that stores a date and time. We need to convert it to a DateTime object so it can be formatted and manipulated. The type of created_at can be defined as follows:

protected $type = [
    'created_at' => 'datetime',
];

Perform custom type conversion

Sometimes, the default conversion provided in the model may not meet our needs. In this case we can add custom type conversion. Below, we will use an example to demonstrate how to add custom type conversion.

Suppose we have a column named year, which stores the string of the year. We want to convert it to an integer type so we can do calculations on it. We can achieve this conversion by using the following code:

protected $type = [
    'year' => 'integer',
];

protected function getYearAttr($value)
{
    return intval($value);
}

protected function setYearAttr($value)
{
    return strval($value);
}

In this example, we first define the data type of the year column as an integer in the $type attribute. Next, we implemented the getYearAttr and setYearAttr methods. The getYearAttr method will convert the string read from the database to an integer, and the setYearAttr method will convert the integer from the PHP class to a string in the database. We used the intval function to convert a string to an integer and the strval function to convert an integer to a string.

Summary

In this article, we explored serial model type conversion in ThinkPHP5 development. We learned what type conversion is and how default type conversion and custom type conversion are performed in the model. Type conversion allows us to map data types in the database to data types in PHP, making it easier for us to process and manipulate data. Type conversion is an essential tool when developing models.

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