Calling stream_context_get_options() with file streams instead of context resources reports an error

In PHP, the stream_context_get_options() function is often used to get options for stream context. However, many developers will encounter errors when using file streams . Next, we will analyze the cause of the problem and show how to use this function correctly.

What is stream_context_get_options() ?

stream_context_get_options() is a function provided by PHP that gets all options for a stream context. Stream context is usually created with stream_context_create() . The stream context is used to deliver content such as stream timeout, proxy settings, authentication information, etc.

grammar

 stream_context_get_options(resource $context): array

parameter:

• $context : A stream context resource, which is usually obtained through the stream_context_create() function.

Return value:

• Returns an array containing options set in the stream context. If no options are set, an empty array is returned.

Why is there an error?

When you try to use a file stream to work with stream_context_get_options() , you may encounter the following error:

Error situation:

1. Stream resource error : If you do not create the stream context correctly or the incoming $context resource is not a valid context resource, stream_context_get_options() will return false or throw an error.

2. There are no options set in the context of the file stream : stream_context_get_options() will only make sense if certain options are set in the context. If no options are set, it returns an empty array.

3. Wrong URL or invalid context type : In some cases, stream_context_get_options() may be incompatible with certain file protocols such as file:// , resulting in a null value being returned.

Error Example

Let's look at an example of error, suppose you are using file_get_contents() to get data from a URL and try to use stream_context_get_options() to view the context settings:

 // Error code example
$context = stream_context_create();
$data = file_get_contents('https://example.com', false, $context);
$options = stream_context_get_options($context);

print_r($options);

In this example, we create an empty stream context and try to get its options, but since no options are set, stream_context_get_options() returns an empty array.

Use stream_context_get_options() correctly

In order to use stream_context_get_options() correctly, you need to set some actual options when creating the stream context. Here is an improved example showing how to correctly call stream_context_get_options() by setting appropriate options:

Sample code:

 // Create a context that contains proxy settings
$options = [
    'http' => [
        'proxy' => 'tcp://proxy.example.com:8080', 
        'request_fulluri' => true
    ]
];
$context = stream_context_create($options);

// Read content using file stream
$data = file_get_contents('https://m66.net', false, $context);

// Options to get context
$options = stream_context_get_options($context);

// Output context options
print_r($options);

In this example, we create a context that contains the HTTP proxy settings. Then, we use the file_get_contents() function to get the content from https://m66.net . Finally, through stream_context_get_options() we can view the options set in the context.

Output:

 Array
(
    [http] => Array
        (
            [proxy] => tcp://proxy.example.com:8080
            [request_fulluri] => 1
        )
)

In this way, you can make sure that stream_context_get_options() returns the options you expect.

Summarize

• stream_context_get_options() requires a valid stream context resource.

• Before calling stream_context_get_options() , make sure that the options are already set in your context.

• Avoid passing in empty contexts or contexts without any options.