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A small dart library to generate Assets dart code from assets folder.
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A small dart library to generate Assets dart code from assets folder. It generates dart class with static const variables in it which can be used to reference the assets safely anywhere in the flutter app.



Widget build(BuildContext context) {
  return Image(image: AssetImage('assets/background.png'));


Widget build(BuildContext context) {
  return Image(image: AssetImage(Assets.background));

Generated Assets Class

class Assets {
  static const String background = 'assets/background.png';

This method allows no error scope for string typos. Also, it provides auto-complete in the IDE which comes very handy when you have large amount of assets.


This is package is an independent library that is not linked to your project. So there's no need to add it to your flutter project as it works as a global command line tool for all of your projects.

pub global activate spider

Run following command to see help:

spider --help


Create Configuration File

Spider provides a very easy and straight forward way to create a configuration file. Execute following command and it will create a configuration file with default configurations in it.

spider create

Now you can modify available configurations and Spider will use those configs when generating dart code.

Use JSON config file

Though above command creates YAML format for config file, spider also supports JSON format for config file. Use this command to create JSON config file instead of YAML.

spider create --json

No matter which config format you use, JSON or YAML, spider automatically detects it and uses it for code generation.

Here's the default configuration that will be in the config file:

  - path: assets/images
    class_name: Images
    package: res

Generate Code

Run following command to generate dart code:

spider build

Watch Directory

Spider can also watch given directory for changes in files and rebuild dart code automatically. Use following command to watch for changes:

spider build --watch

see help for more information:

spider build --help

Smart Watch (Experimental)

The normal --watch option watches for any kind of changes that happens in the directory. However this can be improved my smartly watching the directory. It includes ignoring events that doesn't affect anything like
file content changes. Also, it only watches allowed file types and
rebuilds upon changes for those files only.

Run following command to watch directories smartly.

spider build --smart-watch

Categorizing by File Extension

By default, Spider allows any file to be referenced in the dart code. but you can change that behavior. You can specify which files you want to be referenced.

path: assets
class_name: Assets
package: res
types: [ jpg, png, jpeg, webp, bmp, gif ]

Use Prefix

You can use prefixes for names of the generated dart references. Prefixes will be attached to the formatted reference names.

path: assets
class_name: Assets
package: res
prefix: ic
class Assets {
  static const String icCamera = 'assets/camera.png';
  static const String icLocation = 'assets/location.png';

Advanced Configuration

Spider provides supports for multiple configurations and classifications. If you wanna group your assets by module, type or anything, you can do that using groups in spider.


Suppose you have both vector(SVGs) and raster images in your project and you want to me classified separately so that you can use them with separate classes. You can use groups here. Keep your vector and raster images in separate folder and specify them in the config file.


  - path: assets/images
    class_name: Images
    package: res
  - path: assets/vectors
    class_name: Svgs
    package: res

Here, first item in the list indicates to group assets of assets/images folder under class named Images and the second one indicates to group assets of assets/vectors directory under class named Svgs.

So when you refer to Images class, auto-complete suggests raster images only and you know that you can use them with AssetImage and other one with vector rendering library.

Multi-path configuration

From Spider v0.4.0, multiple paths can be specified for a single group
to collect references from multiple directories and generate all the
references under single dart class.


  - paths:
      - assets/images
      - assets/more_images/
    class_name: Images
    package: res
    types: [ .png, .jpg, .jpeg, .webp, .webm, .bmp ]

By using paths, multiple source directories can be specified. Above example will generate references from assets/images and
assets/more_images/ under a single dart class named Images.

Generating Tests

Spider v0.4.0 adds support for generating test cases for generated
dart references to make sure that the asset file is present in the
project. These tests can also be run on CI servers. To enable tests generation, specify generate_tests flag in spider.yaml or spider.json configuration file as shown below.

generate_tests: true

This flag will indicate spider to generate tests for all the generated
dart references.

Enable Verbose Logging

Spider prefers not to overwhelm terminal with verbose logs that are redundant for most of the cases. However those verbose logs come quite handy when it comes to debug anything. You can enable verbose logging by using --verbose option on build command.

spider build --verbose

# watching directories with verbose logs
spider build --watch --verbose


Copyright © 2020 Birju Vachhani

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.
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