Node js : Call an async function in the same file

Question

I have a function defined in a file which calls an async function and also a normal function. I have defined them in this way

const cms_service = {
    fetchSinglePost: function(post){
        const image = await cms_service.fetchImageData(post)
        let single_post = {
            post: cms_service.fetchPostData(post),
            image: image
        }
        return single_post
    },
    fetchPostData: function (post) {
        var post_response = {
            id: post.data[0].id
        }
        return post_response
    },
    fetchImageData: async function (post) {
        let storyplay_response = {}
        if(typeof post.data[0].tmc_storyplay[0] !== 'undefined' && post.data[0].tmc_storyplay[0]){
            const storyplay = await axios.get(cms_service_url+"tmc_storyplay/"+post.data[0].tmc_storyplay[0], requestHeader);
            storyplay_response = {
                id: storyplay.data.id
            }
        }
        return storyplay_response
    }
}
module.exports = cms_service;

But it throws me an error saying

TypeError: this.fetchPostData is not a function

How do I correct this?

tmhao2005 · Accepted Answer · 2020-07-22 06:20:24Z

2

this keyword doesn't make sense in this context. Let's try to re-write by wrapping in object name as following:

const yourObj = {
 foo: () => 1,
 bar: () => yourObj.foo(),
}

module.exports = yourObject;

answered Jul 22, 2020 at 6:20

tmhao2005

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12 Comments

Saeesh Tendulkar Over a year ago

I did the structure as per this. But I dont get the data returned from the async function "fetchImageData". How can I fix this?

VLAZ Over a year ago

@SaeeshTendulkar you have to use await with the asynchronous calls.

Saeesh Tendulkar Over a year ago

@VLAZ yeah. I tried it like this - post: await cms_service.fetchPostData(post). But it throws unknown identifier error

VLAZ Over a year ago

@SaeeshTendulkar I just noticed that fetchPostData doesn't return anything. It assigns a variable and that is it. Same thing with fetchImageData

tmhao2005 Over a year ago

Sorry I don't get what you're keen for. I saw a few problems in your code. If you wish to have something return of fetchImageData, you have to return your modified data like: return { id: storyplay.data.id }. Then you get the result: const yourData = await yourService.fetchImageData(yourPost)

|

Ravi Chaudhary · Accepted Answer · 2020-07-22 09:17:59Z

You need to refactor your service a bit. You can access object key-values within that object.

const cms_service = () => {
    const fetchSinglePost = function(post){
        const image = await fetchImageData(post)
        let single_post = {
            post: fetchPostData(post),
            image: image
        }
        return single_post
    };

    const fetchPostData = function (post) {
        var post_response = {
            id: post.data[0].id
        }
        return post_response
    };

    const fetchImageData = async function (post) {
        let storyplay_response = {}
        if(typeof post.data[0].tmc_storyplay[0] !== 'undefined' && post.data[0].tmc_storyplay[0]){
            const storyplay = await axios.get(cms_service_url+"tmc_storyplay/"+post.data[0].tmc_storyplay[0], requestHeader);
            storyplay_response = {
                id: storyplay.data.id
            }
        }
        return storyplay_response
    };
}
module.exports = cms_service;

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