猫鼬聚合命令的GraphQL错误返回结果 [英] GraphQL error returning result of mongoose aggregate command

问题描述

此问题与在此处发布的答案有关

我需要从GraphQL查询返回聚合结果.这是查询代码:

I need to return an aggregation result from a GraphQL query. Here is the query code:

const companiesWithNoUsers = {
    type: new GraphQLList(CompanyType),
    resolve(root, args, context) {
        return Company.aggregate([
            {
                $lookup: {
                    from: "users",
                    localField: "id",
                    foreignField: "company_id",
                    as: "company_users"
                }
            },
            {
                $match: {
                    "company_users:0": {
                        $exists: false
                    }
                }
            }
        ]).exec();
    }
};

我在GraphQL上遇到以下错误:

I´m getting the follwing error at GraphQL:

Expected value of type \"Company\" but got: [object Object].

阅读文档后，我认为该错误与以下语句有关:

After reading the docs, I imagine the error is related to the following statement:

返回的文档是纯JavaScript对象，不是猫鼬文档(因为可以返回任何形状的文档)."

因此，我需要返回一个GraphQL CompanyType.如何将返回值转换为GraphQL预期的格式?有针对此错误的另一种解决方案吗?

So, I need to return a GraphQL CompanyType. How do I cast the return to the format expected to GraphQL ? Is there another solution for this error ?

推荐答案

您可以尝试将结果列表转换为Mongoose文档，然后将结果包装在Promise中，如下所示:

You could try casting the results list to Mongoose documents and wrap the result in a Promise as:

Company.aggregate(pipeline).exec((err, result) => 
    (    
        new Promise((resolve, reject) => {
            if (err) {
                reject(err)
            } else {                    
                resolve(result.map(doc => { 
                    delete doc.company_users;
                    return new Company( doc );
                }))
            }
        })
    ))

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