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86 lines
2.6 KiB
Markdown
86 lines
2.6 KiB
Markdown
# Parameters
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## Concept
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You can use `strapi-utils` to parse the query params to Strapi's standards filters programmatically if you need it.
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## Extracting requests filters
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To transform the query params to Strapi's standard filters a request, you can use the `convertRestQueryParams` function from [strapi-utils](../global-strapi/api-reference.md#strapiutils).
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```js
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const { convertRestQueryParams } = require('strapi-utils');
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module.exports = {
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// when sending a request like GET /products?_sort:id&id=1
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fetchExpensiveProducts: (params, populate) => {
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const filters = convertRestQueryParams(params);
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/**
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* filters = {
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* start: 0,
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* limit: 10,
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* sort: [{ field: 'id', order: 'desc' }],
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* where: [
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* { field: 'id', operator: 'eq', value: 1 },
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* ]
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* }
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*/
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// do sth with them
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},
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};
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```
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## Querying data
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We added a new API to query data base on the new filters API.
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```js
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const { convertRestQueryParams, buildQuery } = require('strapi-utils');
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module.exports = {
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find: async (ctx) => {
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// Convert params.
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const filter = convertRestQueryParams(ctx.request.query);
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return buildQuery({
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model: Article
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filters,
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populate: []
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});
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};
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};
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```
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### SQL databases (bookshelf)
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If you are using a SQL database, calling `buildQuery` will return a [`Bookshelf Query`](https://bookshelfjs.org/api.html) on which you can call other functions (e.g `count`)
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### Mongo database
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If you are using a mongo database calling `buildQuery` returns either a [`Mongoose Query`](https://mongoosejs.com/docs/api.html#Query) or a custom query when used with deep filtering.
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#### Custom Query
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When using the deep filtering feature with mongo, we build an aggregation query to avoid too many round-trips with the mongo DB.
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Doing that means we don't get a Mongoose object as a response but instead a plain JS Object. This brings a some issues like no virtual fields available and no Mongoose lifecycles.
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To deliver the best possible experience, we decided to rehydrate the Mongoose models, forcing us to override the Mongoose query
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```js
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const query = buildQuery({
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model: Product, // you can use any models from strapi.models or strapi.plugins[pluginName].models
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filters: { limit: 10 },
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populate: [],
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});
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```
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returns a query with the following functions
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- `count` => Returns an integer equal to the number of matching entities
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- `lean` => Returns the matching elements as Objects
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- `then(onSucces, onFailure)` => Calls the onSucces with an array of Mongoose objects.
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- `catch(onError)` => Promise catch
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- `group(options)` => Calls the aggregation group function of mongoose
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