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CSVDataImporter.ts
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CSVDataImporter.ts
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////////////////////////////////////////////////////////////////////////////
//
// Copyright 2018 Realm Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////
import fs from 'fs-extra';
import papaparse from 'papaparse';
import { ObjectSchemaProperty, PropertyType } from 'realm';
import moment from 'moment';
import { DataImporter, ImportableFile } from '../DataImporter';
export class CSVDataImporter extends DataImporter {
private static readonly NUMBER_OF_INSERTS_BEFORE_COMMIT = 10000;
public import(realm: Realm, files: ImportableFile[]) {
for (const file of files) {
const className = file.className;
const schema = realm.schema.find(s => s.name === className);
if (!schema) {
throw new Error(
`Unable to import ${file.path}: Class name (${className}) missing from schema`,
);
}
const rawCSV = fs.readFileSync(file.path, 'utf8');
const data = papaparse.parse<any>(rawCSV, {
header: true, // to avoid parsing first line as data
skipEmptyLines: true,
}).data;
realm.beginTransaction();
let numberOfInsert = 0;
for (const [rowIndex, dataRow] of data.entries()) {
const object: any = {};
for (const propName in schema.properties) {
if (propName in dataRow) {
// We know that this is a ObjectSchemaProperty since we're reading it from the realm.schema
const propertySchema = schema.properties[
propName
] as ObjectSchemaProperty;
const dataValue = dataRow[propName];
try {
if (propertySchema.optional && dataValue === '') {
object[propName] = null;
} else {
object[propName] = this.convertToType(
dataValue,
propertySchema.type,
);
}
} catch (e) {
// abort transaction and delete the Realm
realm.cancelTransaction();
throw new Error(
`Parsing error at line ${rowIndex}, expected type "${propertySchema.type}" but got "${dataValue}" for column "${propName}"\nError details: ${e}`,
);
}
}
}
try {
realm.create(schema.name, object);
} catch (e) {
// This might throw, if the CSV violate the current Realm constraints (ex: nullability or primary key)
// or generally if the CSV schema is not compatible with the current Realm.
realm.cancelTransaction();
throw e;
}
numberOfInsert++;
// commit by batch to avoid creating multiple transactions.
if (
numberOfInsert === CSVDataImporter.NUMBER_OF_INSERTS_BEFORE_COMMIT
) {
realm.commitTransaction();
numberOfInsert = 0;
realm.beginTransaction();
}
}
realm.commitTransaction();
}
}
private convertToType(value: string, type: PropertyType) {
switch (type) {
case 'string':
return value;
case 'bool':
return JSON.parse(value.toLocaleLowerCase());
case 'int': {
const parsed = parseInt(value, 10);
if (isNaN(parsed)) {
throw new Error(`Can not parse "${value}" as integer`);
}
return parsed;
}
case 'float':
case 'double': {
const parsed = parseFloat(value);
if (isNaN(parsed)) {
throw new Error(`Can not parse ${value} as float / double`);
}
return parsed;
}
case 'date':
return moment(value).toDate();
default:
throw new Error(`Importing data of type "${type}" is not supported`);
}
}
}