@darwino/darwino/dist/lib/PagingDataFetcher.js

A set of Javascript classes and utilities

import _defineProperty from "@babel/runtime/helpers/esm/defineProperty";

/* 
 * (c) Copyright Darwino Inc. 2014-2017.
 */
export default class PagingDataFetcher {
  constructor(props) {
    _defineProperty(this, "autoFetch", false);

    _defineProperty(this, "pageSize", 100);

    _defineProperty(this, "maxPages", 8);

    _defineProperty(this, "_rowsCount", 0);

    _defineProperty(this, "_eof", false);

    _defineProperty(this, "_pages", []);

    _defineProperty(this, "_loadedPages", []);

    _defineProperty(this, "_fetching", false);

    _defineProperty(this, "_autoFetching", false);

    _defineProperty(this, "_error", false);

    _defineProperty(this, "_errorMsg", null);

    Object.assign(this, props);
  }

  init() {
    this._pages = [];
    this.loadPage(0);
  }

  isFetching() {
    return this._fetching;
  }

  isError() {
    return this._error;
  }

  getErrorMessage() {
    return this._errorMsg;
  }

  hasMoreRows() {
    return !this._error && !this._eof;
  }

  getRow(i) {
    var num = Math.floor(i / this.pageSize);

    var row = this._getRow(num, i); // Prefetch the next page - this will also increase the count


    if (this.autoFetch && !this._autoFetching && !this._eof && num == this._pages.length - 1) {
      this._autoFetching = true; // Just do it once...

      setTimeout(() => {
        this.loadMoreRows();
        this._autoFetching = false; // Just do it once...
      });
    }

    return row;
  }

  getRows(skip, limit) {
    var a = [];

    for (var i = 0; i < limit; i++) {
      a[i] = this.getRow(skip + i);
    }

    return a;
  }

  getRowCount() {
    return this._rowsCount;
  }

  _getRow(num, i) {
    if (num < this._pages.length) {
      if (this._pages[num]) {
        var idx = i - num * this.pageSize;
        return this._pages[num][idx];
      }

      if (this._pages[num] === undefined) {
        this.loadPage(num);
      }
    }

    return {};
  }

  loadMoreRows() {
    if (!this._fetching && !this._eof) {
      this.loadPage(this._pages.length);
    }
  }

  loadPage(num) {
    this._pages[num] = null; // null means loading, undefined means empty until we'll load it

    this.dataLoader(num, this.pageSize).then(data => {
      this._eof = data.length < this.pageSize;
      this._pages[num] = data;
      var nc = num * this.pageSize + data.length;
      this._rowsCount = this._eof ? nc : Math.max(this._rowsCount, nc);
      this._fetching = false;
      this._error = false;
      this._errorMsg = null; //console.log("Loaded page #"+num+", pages="+this.pages.length); //+", ="+JSON.stringify(this.pages[num]));

      if (this.maxPages > 0 && data.length) {
        for (var i = 0; i < this._loadedPages.length; i++) {
          if (this._loadedPages[i] == num) {
            this._loadedPages.splice(i, 1);

            break;
          }
        }

        this._loadedPages.push(num);

        if (this._loadedPages.length > this.maxPages) {
          //console.log("Discard page #"+this.loadedpages[0]);
          this._pages[this._loadedPages[0]] = undefined;

          this._loadedPages.splice(0, 1);
        }
      } // Send an event for the content changed


      if (this.onDataLoaded) this.onDataLoaded(num, this.pageSize);
    }, error => {
      // Error
      this._fetching = false;
      this._error = true;
      this._errorMsg = error.message; // Send an event for the content changed

      if (this.onDataLoaded) this.onDataLoaded(0, 0);
    });
    this._fetching = true;
  }

}
//# sourceMappingURL=PagingDataFetcher.js.map