FileService

Overview

SERVICE This class is a "service" and it is automatically injected if declared as a member in the constructor of the consuming class. - See the constructor section below for details - See the Automatic Instance Injection page for details on the topic

The FileService class provides methods to work with files

Properties

No properties

Methods

• fileWrite

• fileRead

• fileDelete

• fileExists

• getDirFiles

Constructor

Don't instantiate directly instances of the SqlQueryServiceclass.

SqlQueryService instances are automatically injected by Dynamics Mobile framework.

import { View, SqlQueryService } from '$dms';
import { Customer } from '$dms-bo';

@View()
export class MyView {

  constructor(
    //we need to only declare the member
    private SqlQueryService: SqlQueryService
  ){
  
  }

  async load(){      
    //we can now use the injected instance 
    let  value = await this.SqlQueryService.execute(`select * from ${Customer.boTableName}}`);   
  }

}

App Types

📳 Mobile 🌐 Backend

There is a difference in the behaviour of the FileService API in mobile and backend apps. Read the File Access documentation for more details

▶️ fileWrite(fileName: string, fileContent:string): Promise<void>

Description

fileWrite method creates new file with given filename and filecontent. The method will overwrite the file if it already exists without throwing error

Parameters

• fileName: string - file name including directory and extension. myfolder/myfile.json

• fileContent: string - string content encoded in utf-8

Returns

void

Example

import { FileService } from '@dms';
import { Customer } from '@dms-bo';

...
const customers = await Customer.query().executeSelect();
await this.FileService.fileWrite('customers/list.json', JSON.stringify(customers));

fileRead(fileName: string): Promise<string>

Description

fileRead method reads and returns the content of existing file by given filename. The method throws error if the file does not exists.

Parameters

• fileName: string - the name of the file including the folder and file extension - myfolder/myfile.json

Returns

string content read from the file encoded in utf-8

Example

import { FileService } from '@dms';
import { Customer } from '@dms-bo';

...
const content = await this.FileService.fileRead('customers/list.json');
const customers = JSON.parse(content);

fileDelete(fileName: string): Promise<void>

Description

fileDelete method deletes a file by given filename. The method will not throw error if the file does not exists.

Parameters

• fileName: string - the name of the file including the folder and file extension - myfolder/myfile.json

Returns

void

Example

import { FileService } from '@dms';
import { Customer } from '@dms-bo';

...
await this.FileService.fileDelete('customers/list.json');

fileExists(fileName: string): Promise<boolean>

Description

fileExists method returns true if the file with the given filename exists.

Parameters

• fileName: string - the name of the file including the folder and file extension - myfolder/myfile.json

Returns

true if the file exists false if the file does not exists

Example

import { FileService } from '@dms';
import { Customer } from '@dms-bo';

...
const exists = await this.FileService.fileExists('customers/list.json');
if(exists){
    const content = await this.FileService.fileRead('customers/list.json');
}

getDirFiles(folder: string): Promise<Array<string>>

Description

getDirFiles method returns list of files contained in the given folder.

Parameters

• folder: string - the full name of the file folder- myfolder/subfolder

Returns

List of strings, where each array element is a full file path for a file contained in the given folder.

Example

import { FileService } from '@dms';
import { Customer } from '@dms-bo';

...
const files = await this.FileService.getDirFiles('customers');
let combinedContent = '';
for(let i=0;i<files.length;i++){
    const filePath = files[i];
    const content = await this.FileService.readFile(filePath);
    combinedContent+=content;
}