Angular : Adding the result of Http response to a map

Question

I am sending simultaneous multiple HTTP calls from my Angular app. I want to save the response of HTTP calls in a Map.

data: Map<number, any> = new map<number,any>();

------------------------------------------------------

this.transactions.foreach((url)=>{
   this.http.post(url,{})
                         .map(data => this.data.set(txnNumber, data))
})

Now since HTTP requests are sent at same time and there are chances of collision in terms of retrieval and usage of Map, it would re-write it. How can we synchronize it ?

Daniel Caldera · Accepted Answer · 2018-07-04 11:41:55Z

2

You can use zip operator. Create an Array with the request storing the transaction index, and execute with zip, when all transactions complete use a foreach to get the data of the transactions.

data: Map<number, any> = new map<number,any>();

------------------------------------------------------

const requests = this.transactions.foreach((url, index)=> {
    return this.http.post(url,{})).map((response) => ({txNumber: index, response})
});
Observable.zip(...requests)
    .map((results: any[]) => {
        results.foreach((data) => this.data.set(data.txNumber, data.response))
    });

answered Jul 4, 2018 at 11:41

Daniel Caldera

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