Firestore/src/V1beta1/TransactionOptions.php
public function setReadOnly($var)
    {
        GPBUtil::checkMessage($var, \Google\Cloud\Firestore\V1beta1\TransactionOptions_ReadOnly::class);
        $this->writeOneof(2, $var);

        return $this;
    }
public function setReadOnly($var)
    {
        GPBUtil::checkMessage($var, \Google\Cloud\Firestore\V1beta1\TransactionOptions_ReadOnly::class);
        $this->writeOneof(2, $var);

        return $this;
    }
public function setReadOnly ( $ var ) { GPBUtil :: checkMessage ( $ var , \ Google \ Cloud \ Firestore \ V1beta1 \ TransactionOptions_ReadOnly :: class ) ; $ this -> writeOneof ( 2 , $ var ) ; return $ this ; }
The transaction can only be used for read operations.

Generated from protobuf field <code>.google.firestore.v1beta1.TransactionOptions.ReadOnly read_only = 2;</code>
@param \Google\Cloud\Firestore\V1beta1\TransactionOptions\ReadOnly $var
@return $this
The transaction can only be used for read operations .