# icu_provider_fs [](https://crates.io/crates/icu_provider_fs)
`icu_fs_data_provider` is one of the [`ICU4X`] components.
It reads ICU4X data files from the filesystem in a given directory. It can also export data to
the filesystem via an iterable data provider (see the `export` module).
## Examples
```rust
use icu_provider_fs::FsDataProvider;
let provider = FsDataProvider::try_new("/path/to/data/directory")
.expect_err("Specify a real directory in the line above");
```
## Directory Structure
The ICU4X data directory has a file named *manifest.json* at the root, and a nested structure
with category (ResourceCategory), subcategory@version, optional variant, and language identifier
as the leaf data files. For example, Arabic JSON data for cardinal plurals lives at
*plurals/cardinal@1/ar.json*.
The exact form of the directory structure may change over time. ICU4X uses metadata from
*manifest.json* to dynamically interpret different versions of the directory structure.
```
├── manifest.json
├── dates
│ └── gregory@1
│ ├── ar-EG.json
│ ├── ar.json
│ ├── be.json
│ ⋮
│ └── und.json
└── plurals
├── cardinal@1
│ ├── ar.json
│ ├── be.json
│ ⋮
│ └── und.json
└── ordinal@1
├── ar.json
├── be.json
⋮
└── und.json
```
## Resource Formats
`ICU4X` data can be stored in different formats. At the moment there are:
* JSON - Textual format, easy to read
* Postcard - Binary, small `#[no_std]` resource format
* Bincode - Binary, fast resource format
The directory passed to the [`FsDataProvider`] constructor may contain either of them.
## Exporting data
To generate the data required for [`FsDataProvider`], run the following:
```bash
icu4x-datagen --keys all --locales full --format dir
```
To export `postcard` format, use
```bash
icu4x-datagen --keys all --locales full --format dir --syntax postcard
```
*Notice:* In order to use encoded data in production, [`icu_provider`](crate) has to be
added with `deserialize_{bincode_1, json, postcard_1}` Cargo feature.
[`ICU4X`]: ../icu/index.html
## More Information
For more information on development, authorship, contributing etc. please visit [`ICU4X home page`](https://github.com/unicode-org/icu4x).