Process job with Python Asset Builder - Lumberyard User Guide

Process job with Python Asset Builder

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Asset Processor calls the registered callback when it has a job for the builder to begin processing. The callback processes the source asset file, performs all the work inside the temporary directory, creates at least one product asset file, registers the product asset files via a JobProduct entry inside a ProcessJobResponse instance, and returns a success value inside the ProcessJobResponse.


This is the input into the OnProcessJobRequest function to perform the steps that are needed to process a source asset file. This contains the input data that's needed to process the job for the source asset file.

The jobDescription field contains the job parameters that the OnCreateJobs step created for this job.

The tempDirPath field is the path to the temporary directory that the builder uses to write out intermediate and final product asset files output by this job. The output files are stored inside the temporary directory relative to where the final product asset file will be placed in the cache and pak files.

The sourceFileUUID field is both the unique ID of the source asset file, and the first part of the Asset ID that is used for all the product files output by this job. The only way to differentiate the product files is the subId used in the JobProduct structure.


class azlmbr.asset.builder.ProcessJobRequest - sourceFile (str) Relative source file name - watchFolder (str) Watch folder for this source file - fullPath (str) Full source file name - builderGuid (azlmbr.math.Uuid) Builder id - jobDescription (azlmbr.asset.builder.JobDescriptor) Job descriptor for this job created in OnCreateJobs - tempDirPath (str) Temp directory that the builder should use to create job outputs for this job request - platformInfo (azlmbr.asset.builder.PlatformInfo) The information about the platform that this job was emitted for - sourceFileDependencyList (list of azlmbr.asset.builder.SourceFileDependency) Source file dependency information - sourceFileUUID (azlmbr.math.Uuid) The UUID of the source file - jobId (number) Job id for this job, this is also the address for the JobCancelListener


This is the class that the OnProcessJobRequest callback returns to describe the job's results. The ProcessJobResponse contains job data that indicates the outputs from the job in the outputProducts field, the result code, and schedule sources to be reprocessed.

The resultCode field defaults to azlmbr.asset.builder.ProcessJobResponse_Failed. Returning an empty ProcessJobResponse indicates that the job failed.

The outputProducts field indicates what product files need to be copied to the project cache folder. If this is empty, it indicates that the job failed.

The sourcesToReprocess field triggers a rebuild of source assets (via absolute paths) due to the work performed in this job. To reprocess these sources, the builder updates fingerprints in CreateJobs of those builders that process them, like changing source dependencies.


class azlmbr.asset.builder.ProcessJobResponse - resultCode (azlmbr.asset.builder.ProcessJobResponse ResultCode) baz - outputProducts (list of azlmbr.asset.builder.JobProduct) List of job product files - requiresSubIdGeneration (bool) Used to determine if legacy RC products need sub ids generated for them - sourcesToReprocess (list of str) List of absolute source paths to trigger rebuilds

ProcessJobResponse ResultCode

The process job response result code has both a 'Success' and a 'Failure', but it also has some specific failure cases, such as detecting a crash or network issues.

azlmbr.asset.builder.ProcessJobResponse ResultCode

# When everything was processed correctly the job should return ProcessJobResponse_Success azlmbr.asset.builder.ProcessJobResponse_Success # If the job did not create ALL of the expected outputs it should return ProcessJobResponse_Failed azlmbr.asset.builder.ProcessJobResponse_Failed # If a tool or internal API returned an exception it should return ProcessJobResponse_Crashed azlmbr.asset.builder.ProcessJobResponse_Crashed # If the job detected a cancellation during processing it should return ProcessJobResponse_Cancelled azlmbr.asset.builder.ProcessJobResponse_Cancelled # If the job could not reach a remote service or resource it should return ProcessJobResponse_NetworkIssue azlmbr.asset.builder.ProcessJobResponse_NetworkIssue


A successful processing of a source asset returns one or more JobProduct entries in the ProcessJobResponse's outputProducts field.

The productSubID field is a stable and unique product identifier for each product file created by this process job for the source asset file. It can be any unsigned 32-bit integer that disambiguates different outputs from the same source. If builder source asset files produce only one product, the builder can use 0.

The productAssetType field maps to a C++ AZ::Data::AssetData type ID.

One way to determine the asset type ID from Python is to call the AssetCatalogRequestBus using the asset's display name:

assetType = azlmbr.asset.AssetCatalogRequestBus(azlmbr.bus.Broadcast, 'GetAssetTypeByDisplayName', "Font") print(f'Asset type {assetType}')

dependenciesHandled indicates to the Asset Processor that the builder has output all possible dependencies for this source asset file for this job product file. This can be true if there are no output product files. This should be set to True only if the builder outputs its dependencies or the output product doesn't have dependencies. When set to False, Asset Processor emits a warning that dependencies have not been handled.

The JobProduct constructor takes in a product file name (relative to the source asset path), an asset type (Uuid), and a product sub-ID number.


class azlmbr.asset.builder.JobProduct - productFileName (str) Relative or absolute product file path - productAssetType (azlmbr.math.Uuid) The asset type ID this product file loads into the asset catalog - productSubID (number) A stable product identifier - productDependencies (list of ProductDependency) Product assets this source asset depends on - pathDependencies (set of ProductPathDependency) Specifies dependencies by relative path to source assets - dependenciesHandled (bool) Indicates that the builder has output all possible dependencies + JobProduct(productFileName:str, productAssetType:azlmbr.math.Uuid, productSubID:number) A constructor to set a job product


The product dependency information that the builder sends to Asset Processor to indicate that a product asset depends on another product asset during load.


class azlmbr.asset.builder.ProductDependency - dependencyId (azlmbr.math.Uuid) Asset ID of this product asset dependency


The ProductPathDpendency represents the product's dependency information that the builder detected on another product file (relative to the source asset path). If the source asset ID can be determined, we recommend that you use the productDependencies instead to indicate the product's dependency information in terms of asset IDs. It's preferable to depend on product files whenever possible, to avoid introducing unintended dependencies.

The dependencyType field indicates if the path points to a source file or a product file.


class azlmbr.asset.builder.ProductPathDependency - dependencyPath (str) Relative path to the asset dependency - dependencyType (azlmbr.asset.builder.ProductPathDependency Type) Indicates if the dependency path points to a source file or a product file

ProductPathDependency Type

ProductPathDependency Type indicates how to use the dependency path in the ProductPathDependency. A dependency on a source file is converted into dependencies on all product files produced from the source. It's preferred to depend on product files whenever possible, to avoid introducing unintended dependencies.

azlmbr.asset.builder.ProductPathDependency Type

# If the source asset depends on another product asset file the value should be SourceFile azlmbr.asset.builder.ProductPathDependency_ProductFile # If the source asset depends on another source asset the value should be ProductFile azlmbr.asset.builder.ProductPathDependency_SourceFile

Example: Process

This is a simple example of how the asset builder might process a job when Asset Processor detects a new or changed source asset file in the watch folders of the registered pattern.

# Using the incoming 'request' find the type of job via 'jobKey' to determine what to do def on_process_job(args): try: # Get request information request = args[0] # Prepare output folder basePath, _ = os.path.split(request.sourceFile) outputPath = os.path.join(request.tempDirPath, basePath) os.makedirs(outputPath) # Write out a simple file productFileNameOnly = 'myfile.txt' filename = os.path.join(outputPath, productFileNameOnly) file = open(filename, "w+") file.write('some data') file.close() # Prepare output entry data productOutputs = [] basePath, sceneFile = os.path.split(request.sourceFile) assetProductName = os.path.join(basePath, productFileNameOnly) outputFilename = os.path.join(request.tempDirPath, assetinfoFilename) # Create job product entry assetType = azlmbr.math.Uuid_CreateString('{F67CC648-EA51-464C-9F5E-4A9CE41A7F86}', 0) product = azlmbr.asset.builder.JobProduct(assetProductName, assetType, 0) product.dependenciesHandled = True productOutputs.append(product) # Fill out response object response = azlmbr.asset.builder.ProcessJobResponse() response.outputProducts = productOutputs response.resultCode = azlmbr.asset.builder.ProcessJobResponse_Success return response except: # An exception should record a proper failure response = azlmbr.asset.builder.ProcessJobResponse() response.resultCode = azlmbr.asset.builder.ProcessJobResponse_Crashed return response