A package to simplify wrapper model lambda functions in Janis Services
npm install @janiscommerce/lambda-model-wrapper!Build Status
A package to simplify wrapper model lambda functions in Janis Services
sh
npm install @janiscommerce/lambda-model-wrapper
`:page_with_curl: Usage
$3
LambdaGet is used to wrap the
and getPaged() method from models.#### Configuration
* The _getter_
modelClass should return the Model for our entity.
* You can use mustHaveClient to defines if the function will be used for Client models. _default_ true.
* You can use mustHavePayload to make payload mandatory or not. _default_ false.> ℹ️ The payload is used to apply params to the
get() method, this will be explained below.#### Parameters
All parameters are _optional_
*
fields. _String Array_ to reduce response. For more information see @janiscommerce/model.
excludeFields. _String Array_ to reduce response. Since 2.1.0*. For more information see @janiscommerce/model.
* allItems. _Boolean_ to obtain all items, using getPaged() method. _default_ false. _Since 2.0.0_
* calculateTotals. _Boolean_ to calculate totals with getTotals() method. _default_ false. _Since 2.0.0_
* filters, page, limit, order, changeKeys. Classic get() parameters. For more information see @janiscommerce/model.
formatParams. _Object_ to pass parameters to format() method. Since 2.1.0*. See Formatting results below.
onlyTotals. _Boolean_ to only calculate totals with optional filters. Since 4.0.0*.#### Formatting results
The optional _method_ async
format(items, formatParams) allows you to format every item.
The formatParams can be used give different behaviors to the function.#### Totals
To obtain the totals _object_ is required to
#### Response
The response of the lambda functions is explained in the @janiscommerce/lambda package.
#### Examples
First you need to create your lambda function.
`js
'use strict';const { Handler } = require('@janiscommerce/lambda');
const { LambdaGet } = require('@janiscommerce/lambda-wrapper-model');
const ProductModel = require('../../models/product');
class GetProduct extends LambdaGet {
get modelClass() {
return ProductModel;
}
async format(items, { countImages }) {
return items.map(item => ({
...item,
...countImages && { imagesCount: item?.images.length || 0 }
}));
}
}
module.exports.handler = (...args) => Handler.handle(GetProduct, ...args);
`For using the lambda you need to invoke with the @janiscommerce/lambda package.
js
'use strict';const { Invoker } = require('@janiscommerce/lambda');
async () => {
const response = await Invoker.clientCall('GetProduct', 'my-client-code');
/**
* response.payload: {
items: [
{ id: 1, referenceId: 'coke-2lt', name: 'Coke lts', stock: 100, images: ['coke-2lt.jpg'] },
{ id: 2, referenceId: 'pepsi-2lt', name: 'Pepsi 2lts', stock: 100 },
{ id: 3, referenceId: 'fanta-2lt', name: 'Fanta 2lts', stock: 95 }
]
}
*/
const filteredResponse = await Invoker.clientCall('GetProduct', 'my-client-code', {
filters: { stock: 100 },
fields: ['referenceId', 'images'],
calculateTotals: true,
formatParams: { countImages: true }
});
/**
* filteredResponse.payload: {
items: [
{ id: 1, referenceId: 'coke-2lt', images: ['coke-2lt.jpg'], imagesCount: 1 },
{ id: 2, referenceId: 'pepsi-2lt', imagesCount: 0 }
],
totals: { total: 2, page: 1 }
}
*/
};
`$3
The LambdaGroupAggregate wrapper allows you to easily create a Lambda that performs a MongoDB with a simple $group by a specific field.This wrapper is designed for one Lambda per service, and supports grouping for multiple entities using a common pattern.
#### ✅ When to use
Use LambdaGroupAggregate if you want to expose a Lambda that groups documents by a specific field and returns a count for each group.
#### 📦 Usage
Extend the LambdaGroupAggregate class and define the entities getter with the available entities for this service.
Each entity must be mapped to its corresponding model class.
`javascript
'use strict';const { Handler } = require('@janiscommerce/lambda');
const { LambdaGroupAggregate } = require('@janiscommerce/lambda-model-wrapper');
const ProductModel = require('./models/product');
const ProductImageModel = require('./models/product-image');
const BrandModel = require('./models/brand');
class GroupAggregate extends LambdaGroupAggregate {
get entities() {
return {
product: ProductModel
'product-image': ProductImageModel,
brand: BrandModel
};
}
};
module.exports.handler = (...args) => Handler.handle(GroupAggregate, ...args);
`#### 📤 Expected Input
The request body should include the following:
json
{
"entity": "product",
"field": "status"
}
`*
: The key defined in the entities getter (e.g. 'product')
* field: The field in the model to group by (e.g. 'status')#### 📥 Response
The Lambda will respond with an object containing the group values and the corresponding counts:
`json
{
"active": 450,
"inactive": 20,
"error": 1
}
`#### ⚠️ Field Index Requirement
Important: The field provided in the request body must have an index defined in the corresponding MongoDB collection.
Internally, the aggregation uses a
to force index usage:If the specified field is not indexed with
{ [field]: 1 }, the lambda will fail with an error like:> MongoServerError: hint provided does not correspond to an existing index
✅ Make sure to create the appropriate index in your model or migration before using this lambda.
#### 🧪 Example Aggregation
Internally, the Lambda will run a simple
$group aggregation on the selected model:`javascript
await model.aggregate([
$group: {
_id: $${field},
count: { $sum: 1 }
},
], {
allowDiskUse: true,
hint: { [${field}]: 1 }
});
`#### 📡 How to invoke
To call a Lambda using LambdaGroupAggregate, use the
package from another service.`javascript
'use strict';const { Invoker } = require('@janiscommerce/lambda');
const result = await Invoker.clientCall('your-service-name', 'your-lambda-name', {
entity: 'product',
field: 'status'
});
`#### ✅ Result
The result will be an object mapping the grouped field values to their count:
javascript
{
active: 450,
inactive: 20,
error: 1
}
`* If the entity or field is missing or invalid, the Lambda will respond with a