> ## Documentation Index
> Fetch the complete documentation index at: https://developers.lucca.fr/llms.txt
> Use this file to discover all available pages before exploring further.

# Features

> Features of the Legacy API, and the differences between v3 and v4 API generations.

These Legacy APIs may suffer from inconsistencies between endpoints, most likely due to them adhering
to a different standard: either v3 or v4.

The easiest way of figuring out which standard a Legacy API endpoint adheres to si to check its URL:

* if it starts with `/api/v3/**`, then it is definitely a "v3" API.
* if it contains the name of an application, e.g. `/timmi-absences/api/**`, then it most likely is a "v4" API.

Here is a recap of behavioral differences between both standards:

| Feature                 | v3                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | v4                                                                                                                                                                                                                                                                     |
| :---------------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Expanding responses** | By default, only 3 properties are returned: `id`, `name` and `url`. You may include more properties, and even those of related resources, through the use of the `?fields` query parameter. <br /><br />Nested objects properties can be included like this: `?fields=id,nestedObject[a,b,c]`.                                                                                                                                                                                                                                                                   | All properties are always returned, except the total number of items of a collection, which can be included with the `?fields.root=count` query parameter. You have no control over this.                                                                              |
| **Paging**              | Paging is handled through two comma-separated parameters in a single query parameter: `?paging={offset},{page_size}`. `{offset}` is the index of the first item to retrieve in the collection. For example, to retrieve the first page of 100 items: `?paging=0,100`. <br /><br /> The total number of items across all pages can be retrieved through `?fields=collection.count`.                                                                                                                                                                               | Paging is handled through 2 query parameters: `?limit={page_size}` and `?page={page_number}`. For example, to retrieve the first page of 100 items: `?limit=100&page=1`. <br /><br />Retrieve the total number of items across all pages through `?fields.root=count`. |
| **Filtering**           | You can filter out items of a collection by most of their properties. <br /><br />Strict equality with `?{propertyName}={value}` or inequality through `?{propertyName}=notequal,{value}`. <br /><br />Date comparisons:  `?{dateProperty}=since,{date}` or `?{dateProperty}=until,{date}` or `?{dateProperty}=between,{start},{end}`. <br /><br />Numbers comparisons through `?{numberProperty}=greaterthan,{value}` or `?{numberProperty}=greaterthanorequal,{value}` or `?{numberProperty}=lessthan,{value}` or `?{numberProperty}=lessthanorequal,{value}`. | The only filters that are supported are documented in the API reference as query parameters.                                                                                                                                                                           |
| **Sorting**             | You can sort on most properties through `?orderBy={propertyName},{direction}` where `{direction}` is either `"asc"` or `"desc"`.                                                                                                                                                                                                                                                                                                                                                                                                                                 | Identical to the [sorting feature in the Lucca API](../../documentation/using-api/sorting). You can sort on a subset of properties through the `?sort` query parameter, those that are documented in the API reference.                                                |
| **Representations**     | The representation of the resource is contained in the `data` property of the root JSON object. <br /><br />Items of a collection are entries of the `data.items` array.                                                                                                                                                                                                                                                                                                                                                                                         | The representation of the resource is at the root of the JSON object. <br /><br />Items of a collection are entries of the `items` array.                                                                                                                              |