Fetch and join JSON objects from multiple API calls

Question

Sorry if my English is bad and write comment if you don't understand (I will edit post). I have script that gets JSON and parses it with order (How I can parse json with arrays by custom order?). It works well for one JSON. My problem is that I need to parse several JSON (like in script 3 JSON) at the same time to get correct order of md5's.

I tried connect JSON files to get one JSON for parsing, but it is not connecting. Script:

var jsonForparse =[]
  for (page=1;page<3;page++) {

url = "https://some.url/to/json"+page+".json";
xhr.open('GET', url, false);
xhr.send();
json=xhr.responseText ;
//Parse json string
json=JSON.parse(json);
//Connect jsons to jsonForparse
     js =json.concat(js)

  }
//Parse jsonForparse
md5= ids.map(id => jsonForparse.posts.find(post => post.id === id))

How should I parse json's or connect json's to parse them to get correct order of md5's Example: Should get:

md5=[12,34,56,78,90,100]

Order:

ids=[2227726,2277,2218681,22881,6659,2236659]

Json1:


{
   "posts":[
      {
         "id":2236659,

         "file":{

            "size":1325351,
            "md5":"100"
         }
      },
      {
         "id":2227726,

         "file":{

            "size":1182791,
            "md5":"12"
         }
      },
      {
         "id":2218681,

         "file":{
"size":1241188,
"md5":"56"
         }
      }
   ]
}

Json2:

{
   "posts":[
      {
         "id":6659,

         "file":{

            "size":1325351,
            "md5":"90"
         }
      },
      {
         "id":2277,

         "file":{

            "size":1182791,
            "md5":"34"
         }
      },
      {
         "id":22881,

         "file":{
"size":1241188,
"md5":"78"
         }
      }
   ]
}

radulle · Accepted Answer · 2020-05-09 08:40:56Z

1

You need to parse each JSON into object as you are doing for one now and than to join them, after which you have to sort them:

const obj1 = JSON.parse(json1)
const obj2 = JSON.parse(json2)
... \\ this could be a loop if you have more
const obj = [...obj1.posts, ...obj2.posts].sort((a,b) => a.file.md5 - b.file.md5)
const ids = obj.map(e => e.id)
const md5s = obj.map(e => e.file.md5)

edited May 9, 2020 at 8:40

answered May 9, 2020 at 8:35

radulle

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2 Comments

Tofi Over a year ago

I used obj=[...obj1.posts, ...obj2.posts] with some improvement. I connected it with that then parsed normally with md5= ids.map(id => obj.find(post => post.id === id))

radulle Over a year ago

@Tofi if I understand you want to sort by IDs and have whole objects available, than maybe simpler solution (if IDs are numbers) would be: ''' obj = [...obj1.posts, ...obj2.posts].sort((a,b) => a.file.id- b.file.id) '''

Constantin Guidon · Accepted Answer · 2020-05-09 11:09:20Z

1

Embrace the asynchronous nature of JS :p, performs you http calls asynchronously on the first line. Then wait for them to be ready with Promise.all , and finally merge and sort them.

const p = [1, 2, 3].map(idx => fetch(`https://some.url/to/json${idx}.json`).then(res => res.json()));

Promise.all(p).then(results => {
    let posts = results.reduce((acc, val) => acc = [...acc, ...val.posts], [])
    let sorted = ids.map(id => posts.find(post => post.id === id))
    // do smthg here
});

edited May 9, 2020 at 11:09

answered May 9, 2020 at 9:31

Constantin Guidon

1,89218 silver badges22 bronze badges

6 Comments

Tofi Over a year ago

I need order via list of id. Like in end of myscript.

Constantin Guidon Over a year ago

so in sort change .sort((a, b) => a.file.md5 - b.file.md5) by this .sort((a, b) => a.id - b.id) edited my response aswell

Constantin Guidon Over a year ago

i fact its not clear what you want seems you're orderning by md5 but you said the contrary, btw with the provided code you can get by.

Tofi Over a year ago

Please look last line of script. There script order json md5 via list. If ids=[2236659,2227726,2277,2218681,22881,6659]then md5=[100,12,34,56,78,90]. It demands of Order in example, script read order of id then change of ordering whoal json.

Tofi Over a year ago

If that not possible then how I can parse each json like another answer. When I parse each json it give me thislist1=[,,,5364,46545,7646];list2=[2846,56645,864854,,,] how I can connect lists with replacing them of there place like this list=[2846,56645,864854,5364,46545,7646]

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