Pnpjs: Is there a clean way to set up a batch that depend on the result of another?

Created on 13 Mar 2019 · 3Comments · Source: pnp/pnpjs

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Please specify what version of the library you are using: [ 1.2.7 ]

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Expected / Desired Behavior / Question

Set up 3 batches:
1st: makes post, merge, and delete requests and pushes new IDs of posted items to an array
2nd: makes post, merge, and delete requests where some of the posts require the ID's of previous batch and also pushes the new ID's of the posted items to an array
3rd: makes post, merge, and delete requests where some of the posts require and ID value from both the 1st and 2nd batch results

The need for this comes from trying to keep established relationships via lookup fields in multiple lists.

Observed Behavior

I'm able to successfully set up the first two batches by using a value pushed to an array in the execute().then() portion of the 1st with a Promise.all() to execute the 2nd. The problem is trying to set up the 3rd batch and having it wait for both others to complete before making its calls. I realize this is less to do with the pnpjs library and more just fundamental coding but wanted to ask your advice and see if there is anything in the library set up for this situation.

If my explanation is confusing I can provide a code example that represents what I explained above.

Steps to Reproduce

Make 3 batches the 2nd and 3rd using the IDs from the previous batches.

Any feedback would be appreciated 😅 Thanks!

code answered question

Source

dharnen

Most helpful comment

@koltyakov Poetry in a post my friend. After taking your abstract and expanding it to save an array of results per type of call as well as splitting the chunks of dependent calls in to separate batches it works like a charm. I've read through most of the posts on batching that you and @patrick-rodgers have commented on and found a lot of great info. Thank you very much for the quick and helpful post! =)

dharnen on 13 Mar 2019

👍2

All 3 comments

Hi @dharnen,

Please check the sample how this can be done:

import { sp } from '@pnp/sp';

interface Results {
    [key: string]: {
        data: any;
        error?: string;
    }
}

const wrapBatchPromise = <T>(promise: Promise<T>, res: Results, key: string): void => {
    res[key] = res[key] || { data: null };
    promise
        .then(data => {
            res[key].data = data;
        })
        .catch(error => {
            res[key].error = error.message;
        });
};

(async () => {

    const b = sp.web.createBatch();

    const res: Results = {};
    wrapBatchPromise(sp.web.select('Id,Title').inBatch(b).get(), res, 'req1');
    wrapBatchPromise(sp.web.lists.select('Id,Title').inBatch(b).get(), res, 'req2');

    await b.execute().catch(_ => { /**/ });

    // console.log({ res }); // contains req1 and req2 data or possible errors
    const errors = Object.keys(res)
        .filter(k => typeof res[k].error !== 'undefined')
        .map(k => res[k].error);
    if (errors.length > 0) {
        throw Error(`\n- ${errors.join('\n- ')}`);
    }

    wrapBatchPromise(
        sp.web.lists.select('Id,Title')
            .filter(`Title eq '${res['req2'].data[0].Title}'`)
            .inBatch(b).get(),
        res, 'req3'
    );

    await b.execute().catch(_ => { /**/ });

    return res;

})()
    .then(console.log)
    .catch(console.warn);

The sample is abstract. Just artificial requests in one batch and data usage in the second batch.

wrapBatchPromise shows the idea of how to deal with results and error returned by batch API.

Depending on errors processing strategy, one can collect all possible errors or wrap the logic on the first one by removing empty catch in await b.execute().catch(_ => { /**/ });.