datamodel/src/field-creator.js

Relational algebra compliant in-memory tabular data store

import { FieldType, DimensionSubtype, MeasureSubtype } from './enums';
import { fieldRegistry } from './fields';

/**
 * Creates a field instance according to the provided data and schema.
 *
 * @param {Array} data - The field data array.
 * @param {Object} schema - The field schema object.
 * @return {Field} Returns the newly created field instance.
 */
function createUnitField(data, schema) {
    data = data || [];

    if (fieldRegistry.has(schema.subtype)) {
        return fieldRegistry.get(schema.subtype)
                        .BUILDER
                        .fieldName(schema.name)
                        .schema(schema)
                        .data(data)
                        .rowDiffset(`0-${data.length - 1}`)
                        .build();
    }
    return fieldRegistry
                    .get(schema.type === FieldType.MEASURE ? MeasureSubtype.CONTINUOUS : DimensionSubtype.CATEGORICAL)
                    .BUILDER
                    .fieldName(schema.name)
                    .schema(schema)
                    .data(data)
                    .rowDiffset(`0-${data.length - 1}`)
                    .build();
}


/**
 * Creates a field instance from partialField and rowDiffset.
 *
 * @param {PartialField} partialField - The corresponding partial field.
 * @param {string} rowDiffset - The data subset config.
 * @return {Field} Returns the newly created field instance.
 */
export function createUnitFieldFromPartial(partialField, rowDiffset) {
    const { schema } = partialField;

    if (fieldRegistry.has(schema.subtype)) {
        return fieldRegistry.get(schema.subtype)
                        .BUILDER
                        .partialField(partialField)
                        .rowDiffset(rowDiffset)
                        .build();
    }
    return fieldRegistry
                    .get(schema.type === FieldType.MEASURE ? MeasureSubtype.CONTINUOUS : DimensionSubtype.CATEGORICAL)
                    .BUILDER
                    .partialField(partialField)
                    .rowDiffset(rowDiffset)
                    .build();
}

/**
 * Creates the field instances with input data and schema.
 *
 * @param {Array} dataColumn - The data array for fields.
 * @param {Array} schema - The schema array for fields.
 * @param {Array} headers - The array of header names.
 * @return {Array.<Field>} Returns an array of newly created field instances.
 */
export function createFields(dataColumn, schema, headers) {
    const headersObj = {};

    if (!(headers && headers.length)) {
        headers = schema.map(item => item.name);
    }

    headers.forEach((header, i) => {
        headersObj[header] = i;
    });

    return schema.map(item => createUnitField(dataColumn[headersObj[item.name]], item));
}