在 PHP 中创建事务过滤器以创建 GetTransactionsRequest 对象

Question

我正在编写一个向 DA Ledger 发出请求的客户端。我正在遵循我在之前的帖子 Doing CRUD on the DA Ledger through a gRPC client 中收到的建议。
我需要运行“GetTransactions”rpc。这样做需要 GetTransactionsRequest 对象。 GetTransactionsRequest 对象有一个名为“filter”的必需属性，它的类型为 TransactionFilter。我无法创建满足我需求的事务过滤器。它的 .proto 文件是：

// Used for filtering Transaction and Active Contract Set streams.
// Determines which on-ledger events will be served to the client.

message TransactionFilter {

  // Keys of the map determine which parties' on-ledger transactions are being queried.
  // Values of the map determine which events are disclosed in the stream per party.
  // At the minimum, a party needs to set an empty Filters message to receive any events.
  // Required
  map<string, Filters> filters_by_party = 1;
}

“filters_by_party”的唯一字段是必需的。 在php中设置该字段需要如下函数：

/**
     * Keys of the map determine which parties' on-ledger transactions are being queried.
     * Values of the map determine which events are disclosed in the stream per party.
     * At the minimum, a party needs to set an empty Filters message to receive any events.
     * Required
     *
     * Generated from protobuf field <code>map<string, .com.digitalasset.ledger.api.v1.Filters> filters_by_party = 1;</code>
     * @param array|\Google\Protobuf\Internal\MapField $var
     * @return $this
     */
    public function setFiltersByParty($var)
    {
        $arr = GPBUtil::checkMapField($var, \Google\Protobuf\Internal\GPBType::STRING, \Google\Protobuf\Internal\GPBType::MESSAGE, \Com\Digitalasset\Ledger\Api\V1\Filters::class);
        $this->filters_by_party = $arr;

        return $this;
    }

在 mapFiled 对象中设置值的 php 函数是：

/**
     * Assign the element at the given key.
     *
     * This will also be called for: $arr[$key] = $value
     *
     * @param object $key The key of the element to be fetched.
     * @param object $value The element to be assigned.
     * @return void
     * @throws ErrorException Invalid type for key.
     * @throws ErrorException Invalid type for value.
     * @throws ErrorException Non-existing key.
     */
    public function offsetSet($key, $value)
    {
        $this->checkKey($this->key_type, $key);

        switch ($this->value_type) {
            case GPBType::SFIXED32:
            case GPBType::SINT32:
            case GPBType::INT32:
            case GPBType::ENUM:
                GPBUtil::checkInt32($value);
                break;
            case GPBType::FIXED32:
            case GPBType::UINT32:
                GPBUtil::checkUint32($value);
                break;
            case GPBType::SFIXED64:
            case GPBType::SINT64:
            case GPBType::INT64:
                GPBUtil::checkInt64($value);
                break;
            case GPBType::FIXED64:
            case GPBType::UINT64:
                GPBUtil::checkUint64($value);
                break;
            case GPBType::FLOAT:
                GPBUtil::checkFloat($value);
                break;
            case GPBType::DOUBLE:
                GPBUtil::checkDouble($value);
                break;
            case GPBType::BOOL:
                GPBUtil::checkBool($value);
                break;
            case GPBType::STRING:
                GPBUtil::checkString($value, true);
                break;
            case GPBType::MESSAGE:
                if (is_null($value)) {
                  trigger_error("Map element cannot be null.", E_USER_ERROR);
                }
                GPBUtil::checkMessage($value, $this->klass);
                break;
            default:
                break;
        }

        $this->container[$key] = $value;
    }

例如，我如何将当事方名称“dealer1”和“dealer2”设置为过滤器_by_party 的当事方。我尝试了以下代码：

$parties= new Google\Protobuf\Internal\MapField(Google\Protobuf\Internal\GPBType::STRING,Google\Protobuf\Internal\GPBType::MESSAGE); 
$parties->offsetSet(0,"dealer1"); 
$parties->offsetSet(1,"dealer2"); 

导致以下错误：

PHP Fatal error:  Given value is not message. in /home/vantage/damlprojects/loaner_car/php/ledger_client.php on line 85

我不明白为什么是“消息” filter_by_party 'set' 函数需要。我不知道如何以“消息”的形式写经销商名称。似乎做一些应该很简单的事情却很复杂。将输入 $var 设置为“setFiltersByParty”函数的正确方法是什么？

Answer 1

也许你可以在这里找到一些信息： https://developers.google.com/protocol-buffers/docs/reference/php-generated#fields

对于地图字段，我猜应该是这样的：

$m->getFiltersByParty()["string"] = new Filters();

Answer 2

设置'dealer1'和dealer2'的代码如下：

$parties= new Google\Protobuf\Internal\MapField(Google\Protobuf\Internal\GPBType::STRING,
   Google\Protobuf\Internal\GPBType::MESSAGE, "Com\Digitalasset\Ledger\Api\V1\Filters");

$partyIdentifier = new Com\Digitalasset\Ledger\Api\V1\Identifier();
$partyIdentifier->setPackageId($the_package_id); //last one from ListPackages()
$partyIdentifier->setEntityName("<Module>");  //from DAML code
$partyIdentifier->setModuleName("<Template>"); //from DAML code


$partyInclusiveFilters = new Com\Digitalasset\Ledger\Api\V1\InclusiveFilters();
$partyInclusiveFilters->setTemplateIds(array($partyIdentifier));

$partyFilters = new Com\Digitalasset\Ledger\Api\V1\Filters();
$partyFilters->setInclusive($partyInclusiveFilters);

$parties->offsetSet("dealer1",$partyFilters);
$parties->offsetSet("dealer2",$partyFilters);

将 MapField 构造函数的第三个参数设置为“Com\Digitalasset\Ledger\Api\V1\Filters”很重要。正如 protobuf 文件所示：

message TransactionFilter {

          // Keys of the map determine which parties' on-ledger transactions are being queried.
          // Values of the map determine which events are disclosed in the stream per party.
          // At the minimum, a party needs to set an empty Filters message to receive any events.
          // Required
          map<string, Filters> filters_by_party = 1;
        }

filters_by_party 是具有“过滤器”的 value_type 的 MapField。 “过滤器”是一种消息类型（请参阅您的 transaction_filter.proto 文件），因此 MapField 构造函数需要知道它是什么类型的消息。

经销商名称不是以“消息”的形式写入的，而是“filters_by_party”映射字段中对应于“过滤器”对象的键值。 “过滤器”是一种消息。我猜“简单”是一个相对术语。