Confused by 3 nested array

Question

I'm working on pulling data from an excel file saved on SharePoint Document Library. I'm getting the rows and I'm confused at the data structure. I'm still fairly new to typscript/javascript.

I'm getting the rows back:

private _getRows(documentLibraryID: string, documentID: string, worksheet: string, table: string): Promise<[MicrosoftGraph.WorkbookTableRow]> {
  return new Promise<any>((resolve, reject) => {
    this.props.context.msGraphClientFactory
    .getClient()
      .then((client: MSGraphClient): void => {
        client
          .api(`/sites/${URL}/drives/${documentLibraryID}/items/${documentID}/workbook/worksheets('${worksheet}')/Tables('${table}')/rows`)
          .get((error, response: any, rawResponse?: any) => {
            if (response) {
              let rows:[MicrosoftGraph.WorkbookTableRow] = response.value;

              resolve(rows);
            }
            else {
              reject(error);
            }
          });
        });
  });
}

What I get back:

I try to enumerate through the arrays:

  for (let row of rows) {
    console.log("row: ", row);
    for (let value of row.values) {
      console.log("value: ", value);
      for (let newValue of value.values) {
        console.log("newValue: ", newValue);

      }
    }
  }

But I don't get to the newValue object:

What don't I understand about this structure? It looks like 3 nested arrays.

https://stackoverflow.com/questions/23803743/what-is-the-explicit-promise-construction-antipattern-and-how-do-i-avoid-it — Jonas Wilms, Oct 15 '18 at 20:05
@JonasWilms I'm sorry, what are you trying to say? The object I'm trying to use is returned from Microsoft's Graph API, so I have no control over that. Are you saying something about my `_getRows` method and how I am handling the promise? I'm happy to receive any feedback on my code structuring, i'm pretty new to Typescript/Javascript. — Holden1515, Oct 15 '18 at 20:08
@JonasWilms You're right. I re-read it and I'm still not sure how to improve my promise chaining. — Holden1515, Oct 15 '18 at 20:19
You should return the `new Promise` from inside the `then`, that way if `.getClient()` rejects it can be handled too — Jonas Wilms, Oct 15 '18 at 20:23

score 3 · Accepted Answer · answered Oct 15 '18 at 20:03

The problem is that when you're reaching to this point: for (let value of row.values), value is indeed an array. So there's no need of doing value.values.

This code should work fine:

for (let row of rows) {
    console.log("row: ", row);
    for (let valueArr of row.values) {
      console.log("value: ", valueArr);
      for (let newValue of valueArr) {
        console.log("newValue: ", newValue);

      }
    }
  }

Hope it helps!

Ha, that was it! Thank you! – Holden1515 Oct 15 '18 at 20:08 — Holden1515, Oct 15 '18 at 20:08

Confused by 3 nested array

1 Answers1