thinkphp cannot get data

When using thinkphp to write a website, we often encounter the problem of not being able to obtain data. This is because thinkphp's data operations are relatively complex and require certain skills to operate correctly. This article will introduce several common data acquisition methods and solutions.

1. Use the query constructor to obtain data

The query constructor is a data manipulation method of thinkphp. You can obtain data by calling the constructor method in a chain. For example:

$data = Db::table('users')->where('id', $id)->find();

The above code indicates obtaining the user information with ID $id in the users table. However, if no matching results are found when retrieving the data, $data will be an empty array instead of null. This is because the find() method returns an array, and if no matching data is found, it returns an empty array.

Solution:

We can use the empty() function to determine whether the variable is empty, for example:

$data = Db::table('users')->where('id', $id)->find();
if(empty($data)){
    //找不到匹配的数据
}else{
    //获取到了匹配的数据
}

2. Use the model class to obtain data

Using model classes to obtain data is a more efficient method. First, you need to define a model class, for example:

namespace appmodel;
use thinkModel;

class Users extends Model{
    protected $table = 'users';
    protected $pk = 'id';
}

The above code indicates that a model class named Users is defined. It inherits from the Model class of ThinkPHP, represents the users table in the database, and specifies the primary key as ID. .

Then, we can use the model class to obtain data:

$user = Users::get($id);

This sentence means to obtain the user information with ID $id. If matching data is found, $user will be a Users object, otherwise it will be null.

Solution:

To determine whether the model object is empty, you can use the is_null() function or the empty() function, for example:

$user = Users::get($id);
if(is_null($user)){
    //找不到匹配的数据
}else{
    //获取到了匹配的数据
}

3. Use the list method to obtain data

More often, we need to obtain a set of data. At this time, you can use the list method to obtain data. For example:

$data = Db::table('users')->where('age', '>', 18)->order('id', 'desc')->limit(10)->select();

This sentence means to get the top 10 users who are older than 18 years old and sort them in reverse order by ID. If no matching data exists, $data will be an empty array.

Solution:

Similar to the first method, we need to use the empty() function to determine whether the variable is empty.

$data = Db::table('users')->where('age', '>', 18)->order('id', 'desc')->limit(10)->select();
if(empty($data)){
    //找不到匹配的数据
}else{
    //获取到了匹配的数据
}

Summary:

The above are some common solutions to why thinkphp cannot obtain data. I hope it can be helpful to everyone. Of course, this is just the tip of the iceberg. We will encounter more complex data operations when using thinkphp. Learning thinkphp requires continuous understanding and practice to improve your programming level.

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