Creating a service handler in the application¶
All services are implemented as heirs from Service - functions of the rest module.
Each service must export a handler function that implements the asynchronous method this._route
, in which it is necessary to register the processed methods and paths that return Promise through the functions this.addHandler
. The processing function will have access to options
, through which - access to data repositories, authorizations, metadata, and classes (if they are specified in the application configuration in the deploy file.json), and also gets an object with the typical name req
- which is the request
object of the express library . The data already parsed to the object will be located in req.body
.
The handler function must return a Promise that resolves to the processing result (for processing in Service modules/rest/lib/interfaces/Service.js
), the handler will output it with the code 200
and the content type Content-Type:application/json
. If during processing there is an error caught by catch, then for errors related to access control, a response will be returned with the error text and with the code 403
, and for all others, the response code is 500
and the error message Internal server error
.
The header can be redefined, for this, in the response you need to give the headers
header type and the object in the data
attribute
Promise.resolve({headers: ['Content-Type: image/png', 'Content-Length: 107'],
data: Buffer.from([0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, 0x00, 0x00, 0x00, 0x0D, 0x49,
0x48, 0x44, 0x52, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x08, 0x06, 0x00, 0x00, 0x00,
0x1F, 0x15, 0xC4, 0x89, 0x00, 0x00, 0x00, 0x06, 0x62, 0x4B, 0x47, 0x44, 0x00, 0xFF, 0x00, 0xFF,
0x00, 0xFF, 0xA0, 0xBD, 0xA7, 0x93, 0x00, 0x00, 0x00, 0x09, 0x70, 0x48, 0x59, 0x73, 0x00, 0x00,
0x2E, 0x23, 0x00, 0x00, 0x2E, 0x23, 0x01, 0x78, 0xA5, 0x3F, 0x76, 0x00, 0x00, 0x00, 0x0B, 0x49,
0x44, 0x41, 0x54, 0x08, 0xD7, 0x63, 0x60, 0x00, 0x02, 0x00, 0x00, 0x05, 0x00, 0x01, 0xE2, 0x26,
0x05, 0x9B, 0x00, 0x00, 0x00, 0x00, 0x49, 0x45, 0x4E, 0x44, 0xAE, 0x42, 0x60, 0x82])
})
Example of implementing a service that outputs lists of objects with filters for the class_string
class in the develop-and-test
application. It is also convenient to study the crud method itself, located at modules/rest/lib/impl/crud.js
const Service = require('modules/rest/lib/interfaces/Service');
/**
* @param {{dataRepo: DataRepository, echoClassName: String}} options
* @constructor
*/
function listClassString(options) {
/**
* @param {Request} req
* @returns {Promise}
* @private
*/
this._route = function(router) {
this.addHandler(router, '/', 'POST', (req) => {
return new Promise(function (resolve, reject) {
try {
let filter = [];
if (req.body.string_text)
filter.push({string_text: {$eq: req.body.string_text}});
if (req.body.string_miltilinetext)
filter.push({string_miltilinetext: {$eq: req.body.string_miltilinetext}});
if (filter.length === 0)
filter = {};
else if (filter.length === 1)
filter = filter[0];
else
filter = {$and: filter};
options.dataRepo.getList(options.stringClassName, {filter: filter}).then(function (results) {
let items = [];
for (let i = 0; i < results.length; i++) {
const props = results[i].getProperties();
const item = {};
for (let p in props) {
if (props.hasOwnProperty(p))
item[props[p].getName()] = props[p].getValue();
}
items.push(item);
}
resolve({data: items});
});
} catch (err) {
reject(err);
}
});
});
}
}
listClassString.prototype = new Service();
module.exports = listClassString;
Request without attributes in the request body
curl -X POST -u demo@local:ion-demo https://dnt.iondv.com:8888/rest/string-list
Returns the entire list
[{"__class":"class_string@develop-and-test",
"__classTitle":"Class \"String [0]\"",
"id":"4567a830-b8ea-11e9-9cdf-7bd384cbb7a5",
"string_text":"example1",
"string_miltilinetext":"example1",
"string_formattext":"<p>example1</p>"},
{"__class":"class_string@develop-and-test",
"__classTitle":"Class \"String [0]\"",
"id":"4a80bdc0-b8ea-11e9-9cdf-7bd384cbb7a5",
"string_text":"example1",
"string_miltilinetext":"example2",
"string_formattext":"<p>example2</p>"},
{"__class":"class_string@develop-and-test",
"__classTitle":"Class \"String [0]\"",
"id":"66dbb3d0-5583-11e6-aef7-cf50314f026b",
"string_text":"Example of the \"String [0]\" type in the \"Text [1]\" view",
"string_miltilinetext":"Example of the \"String [0]\"\r\n in the Multiline text [7] view",
"string_formattext":"Example of the \r\n \"String [0]\" type \r\n in the \r\nFormatted text [7] view"}]
A request with an attribute parameter equal to the value in the string_text attribute Example of the \"String [0]\" type in the \"Text [1]\" view
curl -X POST -d "string_text=Example of the \"String [0]\" type in the \"Text [1]\"" \
-u demo@local:ion-demo https://dnt.iondv.com:8888/rest/string-list
Returns objects that meet the condition
[{"__class":"class_string@develop-and-test",
"__classTitle":"Class \"String [0]\"",
"id":"66dbb3d0-5583-11e6-aef7-cf50314f026b",
"string_text":"Example of the \"String [0]\" type in the \"Text [1]\" view",
"string_miltilinetext":"Example of the \"String [0]\"\r\n in the Multiline text [7] view",
"string_formattext":"Example of the \r\n \"String [0]\" type \r\n in the \r\nFormatted text [7] view"}]
An example of registering a test service, for more details see Registering a service in the application configuration
{
"modules": {
"rest": {
"globals": {
"di": {
"string-list": {
"module": "applications/develop-and-test/service/String-list",
"options": {
"stringClassName": "class_string@develop-and-test",
"dataRepo": "ion://dataRepo"
}
}
To implement multipart query processing, for example, for queries containing files, you can use the library multipart.js
(rest/backend/multipart.js
) of the REST
module. There is an example of implementation in the CRUD
service:
function reqToData(req) {
return multipart(req).then(data => data || req.body);
}
The library util.js
(rest/backend/util.js
), which ensures correct actions when working with files and file storage, also serves this purpose , example from CRUD
:
reqToData(req)
.then(data => <util.js.>prepareUpdates(options, data, cm, req.params.id))