Assembly Definition File Format

Assembly Definition and Assembly Definition Reference assets are JSON files. You can edit the asset files inside the Unity Editor using the Inspector window, but you can also modify the JSON content with an external tool.

Assembly Definition JSON

An Assembly Definition is a JSON object with the following fields:

allowUnsafeCode bool

Optional. Defaults to false. See Allow ‘unsafe’ Code.

"allowUnsafeCode" : true

autoReferenced bool

Optional. Defaults to true. See Auto Referenced.

"autoReferenced": false

defineConstraints string[]

Optional. The symbols that serve as constraints. Can be empty. See Define Constraints.

"defineConstraints": [
        "UNITY_2019",
        "UNITY_INCLUDE_TESTS"
    ]

excludePlatforms string[]

Optional. The platform name strings to exclude or an empty array. The excludePlatforms array must be empty if includePlatforms contains values. You can retrieve the platform name strings with the CompilationPipeline.GetAssemblyDefinitionPlatforms function (support for a platform must be installed for the current Editor when calling this function.) See Platforms.

"includePlatforms": [],
"excludePlatforms": [
        "iOS",
        "macOSStandalone",
        "tvOS"
]

includePlatforms string[]

Optional. The platform name strings to include or an empty array. The includePlatforms array must be empty if excludePlatforms contains values. You can retrieve the platform name strings with the CompilationPipeline.GetAssemblyDefinitionPlatforms function (support for a platform must be installed for the current Editor when calling this function.) See Platforms.

"includePlatforms": [
        "Android",
        "LinuxStandalone64",
        "WebGL"
],
"excludePlatforms": []

name string

Required. Any legal assembly name.

"name" : "MyAssemblyName" 

noEngineReferences bool

Optional. Defaults to false. See No Engine References.

"noEngineReferences": false

optionalUnityReferences string[]

Optional. In earlier versions of Unity, this field serialized the Unity References : Test Assemblies option used to designate the assembly as a test assembly. As of Unity 2019.3, the option is no longer displayed. The field is still supported, but if the asset is reserialized in a newer version of the Unity Editor, the field is replaced by the equivalent assembly references.

See Creating a test assembly for more information about test assemblies.

"optionalUnityReferences": [
    "TestAssemblies"
  ]

overrideReferences bool

Optional. Set to true if precompiledReferences contains values. Defaults to false.

See [Override References].

"overrideReferences": true

precompiledReferences string[]

Optional. The file names of referenced DLL libraries including extension, but without other path elements. Can be empty. This array is ignored unless you set overrideReferences to true.

See Assembly References.

"overrideReferences": true,
"precompiledReferences": [
        "Newtonsoft.Json.dll",
        "nunit.framework.dll"
]

references string[]

Optional. References to other assemblies created with Assembly Definition assets. You can use either the GUID of the Assembly Definition asset file or the name of the assembly (as defined by the name field of the Assembly Definition). You must use the same form for all references in the list. Can be empty.

You can use the AssetDatabase.AssetPathToGUID function to retrieve the GUID of an asset. (The GUID is also part of the metadata associated with every asset.)

Note that the Editor displays a Use GUIDs option in the Assembly Definition Inspector. This option is not serialized in the associated JSON file. Instead, the choice is inferred from the form of reference found in the file.

See Referencing another assembly.

Using GUIDs:

"references": [
        "GUID:17b36165d09634a48bf5a0e4bb27f4bd",
        "GUID:b470eee7144904e59a1064b70fa1b086",
        "GUID:2bafac87e7f4b9b418d9448d219b01ab",
        "GUID:27619889b8ba8c24980f49ee34dbb44a",
        "GUID:0acc523941302664db1f4e527237feb3"
]

Using assembly names:

"references": [
        "Unity.CollabProxy.Editor",
        "AssemblyB",
        "UnityEngine.UI",
        "UnityEngine.TestRunner",
        "UnityEditor.TestRunner"
]

versionDefines object[]

Optional. Contains an object for each version define. This object has three fields:

• name:string – the name of the resource
• expression:string – the expression defining the version or range of versions of the resource
• define:string – the symbol to define

See Version Defines.

"versionDefines": [
    {
        "name": "com.unity.ide.vscode",
        "expression": "[1.7,2.4.1]",
        "define": "MY_SYMBOL"
    },
    {
        "name": "com.unity.test-framework",
        "expression": "[2.7.2-preview.8]",
        "define": "TESTS"
    }
]

Example Assembly Definition JSON strings

Using assembly names for references to other Assembly Definitions and includePlatforms:

{
    "name": "BeeAssembly",
    "references": [
        "Unity.CollabProxy.Editor",
        "AssemblyB",
        "UnityEngine.UI",
        "UnityEngine.TestRunner",
        "UnityEditor.TestRunner"
    ],
    "includePlatforms": [
        "Android",
        "LinuxStandalone64",
        "WebGL"
    ],
    "excludePlatforms": [],
    "overrideReferences": true,
    "precompiledReferences": [
        "Newtonsoft.Json.dll",
        "nunit.framework.dll"
    ],
    "autoReferenced": false,
    "defineConstraints": [
        "UNITY_2019",
        "UNITY_INCLUDE_TESTS"
    ],
    "versionDefines": [
        {
            "name": "com.unity.ide.vscode",
            "expression": "[1.7,2.4.1]",
            "define": "MY_SYMBOL"
        },
        {
            "name": "com.unity.test-framework",
            "expression": "[2.7.2-preview.8]",
            "define": "TESTS"
        }
    ],
    "noEngineReferences": false
}

Using GUIDS for references to other Assembly Definitions and excludePlatforms:

{
    "name": "BeeAssembly",
    "references": [
        "GUID:17b36165d09634a48bf5a0e4bb27f4bd",
        "GUID:b470eee7144904e59a1064b70fa1b086",
        "GUID:2bafac87e7f4b9b418d9448d219b01ab",
        "GUID:27619889b8ba8c24980f49ee34dbb44a",
        "GUID:0acc523941302664db1f4e527237feb3"
    ],
    "includePlatforms": [],
    "excludePlatforms": [
        "iOS",
        "macOSStandalone",
        "tvOS"
    ],
    "allowUnsafeCode": false,
    "overrideReferences": true,
    "precompiledReferences": [
        "Newtonsoft.Json.dll",
        "nunit.framework.dll"
    ],
    "autoReferenced": false,
    "defineConstraints": [
        "UNITY_2019",
        "UNITY_INCLUDE_TESTS"
    ],
    "versionDefines": [
        {
            "name": "com.unity.ide.vscode",
            "expression": "[1.7,2.4.1]",
            "define": "MY_SYMBOL"
        },
        {
            "name": "com.unity.test-framework",
            "expression": "[2.7.2-preview.8]",
            "define": "TESTS"
        }
    ],
    "noEngineReferences": false
}

Assembly Definition Reference JSON

An Assembly Definition Reference is a JSON object with the following field:

reference string

Required. The assembly definition to reference. See Assembly Definition References.

You can reference an Assembly Definition asset using either the name of the assembly or the GUID of the asset.You can use the AssetDatabase.AssetPathToGUID function to retrieve the GUID of an asset. (The GUID is also part of the metadata associated with every asset.)

Using assembly name:

{
    "reference": "AssemblyA"
}

Using Assembly Definition asset GUID

{
    "reference": "GUID:f4de40948f4904ecb94b59dd38aab8a1"
}

See Creating an Assembly Definition Reference asset.