Question

假设我有一个这样的对象：

$user = (object) [
    'username' => 'foo',
    'post' => (object) [
        'title' => 'bar'
     ],

];

现在我想获取用户帖子标题的值，但我想确保user，posts和title都不为null或未定义。现在我正在检查如下：

if(isset($user) && $user->post && $user->post->title)

有更优雅的方式吗？

我不确定我是否在标题中描述得很好。如果您知道更好的措辞，请更正。

Answer 1

isset()接受多个参数，除非全部设置（而不是false），否则将返回null，因此您可以执行此操作：

isset($user, $user->post, $user->post->title)

Answer 2

检查一切都是多余的。您需要检查的是最低级别的属性if (isset($user->post->title)) { // do something }：

    #*****************************************************************
# Neo4j configuration
#*****************************************************************
# The name of the database to mount
#dbms.active_database=graph.db
# Paths of directories in the installation.
#dbms.directories.data=data
#dbms.directories.plugins=plugins
#dbms.directories.certificates=certificates
# This setting constrains all `LOAD CSV` import files to be under the `import` directory. Remove or uncomment it to
# allow files to be loaded from anywhere in filesystem; this introduces possible security problems. See the `LOAD CSV`
# section of the manual for details.
dbms.directories.import=import
# Whether requests to Neo4j are authenticated.
# To disable authentication, uncomment this line
dbms.security.auth_enabled=false
#*****************************************************************
# Network connector configuration
#*****************************************************************

# Bolt connector
dbms.connector.bolt.type=BOLT
dbms.connector.bolt.enabled=true
dbms.connector.bolt.tls_level=OPTIONAL
# To have Bolt accept non-local connections, uncomment this line
 dbms.connector.bolt.address=0.0.0.0:7687

# HTTP Connector
dbms.connector.http.type=HTTP
dbms.connector.http.enabled=true
# To accept non-local HTTP connections, uncomment this line
dbms.connector.http.address=0.0.0.0:7474

# HTTPS Connector
dbms.connector.https.type=HTTP
dbms.connector.https.enabled=true
dbms.connector.https.encryption=TLS
# To accept non-local HTTPS connection, change 'localhost' to '0.0.0.0'
dbms.connector.https.address=0.0.0.0:7473

# Number of Neo4j worker threads.
#dbms.threads.worker_count=

Answer 3

自php 7.0起，使用空合并运算符（??）即可轻松实现。

如果存在并且不为NULL，则返回其第一个操作数；否则返回第二个操作数。

因此，要获取字段的值，同时检查是否已设置所有变量和字段，您只需执行以下操作：

$title = $user->post->title ?? null

Try it online!

如何在PHP中检查是否存在多级对象参数？

3 个答案: