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扩展 erdjs

原文：https://docs.elrond.com/sdk-and-tools/erdjs/extending-erdjs

##### 重要

本节中的文档是初步的，可能会更改。

本教程将引导您完成从 erdjs 扩展和裁剪某些模块的过程。

延伸网络提供商

从@elrondnetwork/erdjs-network-providers开始的默认类应该只作为一个起点。随着你的 dApp 成熟，确保你切换到使用你自己的网络提供商，根据你的需求定制(无论是从默认的衍生还是从头编写一个新的)，直接与Elrond API(或网关)交互。

从头开始执行 HTTP 请求

通过使用axios实用程序执行简单的 HTTP 请求，可以广播交易并从Elrond API(或网关)获取资源。以下是几个例子:

广播交易:

import axios, { AxiosResponse } from "axios";

let tx = new Transaction({ /* provide the fields */ });
// ... sign the transaction using a dApp / signing provider
let data = tx.toSendable();
let url = "https://devnet-api.elrond.com/transactions";
let response: AxiosResponse = await axios.post(url, data, {
    headers: {
        "Content-Type": "application/json",
    }
});
let txHash = response.data.txHash;

提取交易:

let url = `https://devnet-api.elrond.com/transactions/${txHash}`;
let response = await axios.get(url);
let transactionOnNetwork = TransactionOnNetwork.fromApiHttpResponse(txHash, response.data);

查询智能合约(解析结果):

let query = contract.createQuery({
    func: new ContractFunction("foobar"),
    args: [new AddressValue(addressOfAlice)],
    caller: new Address("erd1...")
});

let url = "https://devnet-api.elrond.com/query";
let data = {
    scAddress: query.address.bech32(),
    caller: query.caller?.bech32() ? query.caller.bech32() : undefined,
    funcName: query.func.toString(),
    value: query.value ? query.value.toString() : undefined,
    args: query.getEncodedArguments()
};

let response: AxiosResponse = await axios.post(url, data, {
    headers: {
        "Content-Type": "application/json",
    }
});

let queryResponse = {
    returnCode: response.data.returnCode,
    returnMessage: response.data.returnMessage,
    getReturnDataParts: () => response.data.returnData.map((item) => Buffer.from(item || "", "base64"));
};

let endpointDefinition = contract.getEndpoint("foobar");
let { firstValue, secondValue, returnCode } = resultsParser.parseQueryResponse(queryResponse, endpointDefinition);

扩展默认网络提供商

您还可以从默认的网络提供商(ApiNetworkProvider和ProxyNetworkProvider)派生，并利用doGetGeneric()和doPostGeneric()覆盖/添加额外的方法。

export class MyTailoredNetworkProvider extends ApiNetworkProvider {
    async getEconomics(): Promise<{totalSupply: number, marketCap: number}> {
        let response = await this.doGetGeneric("economics");
        return { totalSupply: response.totalSupply, marketCap: response.marketCap }
    }

    // ... other methods
}

定制待处理交易

如果出于某种原因， erdjs 提供的默认交易完成检测算法不能满足您的要求，您可能希望对交易等待使用不同的策略，例如:

await transactionWatcher.awaitAllEvents(transaction, ["mySpecialEventFoo", "mySpecialEventBar"]);
await transactionWatcher.awaitAnyEvents(transaction, ["mySpecialEventFoo", "mySpecialEventBar"]);

扩展合约结果解析器

如果由于某种原因(例如一个错误)，由 erdjs 提供的默认ResultsParser不能满足您的需求，您可能想要扩展它并覆盖方法createBundleWithCustomHeuristics():

export class MyTailoredResultsParser extends ResultsParser {
    protected createBundleWithCustomHeuristics(transaction: ITransactionOnNetwork, transactionMetadata: TransactionMetadata): UntypedOutcomeBundle | null {
        let returnMessage: string = "<< extract the message from the input transaction object >>";
        let values: Buffer[] = [
            Buffer.from("<< extract 1st result from the input transaction object >>"),
            Buffer.from("<< extract 2nd result from the input transaction object >>"),
            Buffer.from("<< extract 3rd result from the input transaction object >>"),
            // ...
        ]

        return {
            returnCode: ReturnCode.Ok,
            returnMessage: returnMessage,
            values: values
        };
    }
}
重要

当默认ResultsParser行为不当时，请在 GitHub 上打开一个问题，并且也提供尽可能多的关于不可解析结果的细节(例如，如果可能的话提供交易对象的转储——确保删除任何敏感信息)。

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