LoopBack 4 REST API example for getting record with Mysql - mysql

Question

i'm learning loopback 4, i have created model, repository and datasource, it also connected
to mysql and i can retrieve results from http://127.0.0.1:3000/myapi/{id}
in my default example getting by id is :
#get('/citySchedule/{id}', {
responses: {
'200': {
description: 'Schedule model instance',
content: {'application/json': {schema: {'x-ts-type': Schedule}}},
},
},
})
async findById(#param.path.number('id') id: number): Promise<Schedule> {
return await this.ScheduleRepository.findById(id);
}
However, i didnt found any tutorial for getting data with more parameters.
let say mysql table of schedule has contain column id, city_name, city_code, date, task, item.
for example, i want to get "SELECT task, item FROM schedule WHERE city_code=123 AND date=2019-05-01"
my question, how to write code to get those data at loopback controller ?
any example code...
my expectations, i can query from my api :
http://127.0.0.1:3000/myapi/{city_code}/{date}/ to get data results or
http://127.0.0.1:3000/myapi/{city_name}/{date}/

Answer 1

If you have generated your controller using loopback cli, you must have got another method in controller class like this
#get('/citySchedule', {
responses: {
'200': {
description: 'Array of Schedule model instances',
content: {
'application/json': {
schema: {type: 'array', items: {'x-ts-type': Schedule}},
},
},
},
},
})
async find(
#param.query.object('filter', getFilterSchemaFor(Schedule)) filter?: Filter,
): Promise<Schedule[]> {
return await this.ScheduleRepository.find(filter);
}
You can use this API to fetch more filtered data.
Considering your example
SELECT task, item FROM schedule WHERE city_code=123 AND
date=2019-05-01
for this query, you need to hit the API like this.
GET /citySchedule?filter=%7B%22where%22%3A%7B%22city_code%22%3A123%2C%22date%22%3A%222019-05-01%22%7D%2C%22fields%22%3A%7B%22task%22%3Atrue%2C%22item%22%3Atrue%7D%7D
Here, the filter query parameter value is actually url encoded string for the below json string
{
"where":{
"city_code":123,
"date":"2019-05-01"
},
"fields":{
"task":true,
"item":true
}
}