# MongoDB\Driver\TopologyDescription::hasReadableServer

(mongodb >=1.13.0)

MongoDB\Driver\TopologyDescription::hasReadableServer — Returns whether the topology has a readable server

### 说明

final public MongoDB\Driver\TopologyDescription::hasReadableServer(?MongoDB\Driver\ReadPreference `$readPreference` = `null`): bool

Returns whether the topology has a readable server or, if `readPreference` is specified, a server matching the specified read preference.

### 参数

此函数没有参数。

### 返回值

Returns whether the topology has a readable server or, if `readPreference` is specified, a server matching the specified read preference.

### 错误／异常

- Throws MongoDB\Driver\Exception\InvalidArgumentException on argument parsing errors.

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