Describing Data Objects

You can describe objects (files, app(let)s, and workflows) on the DNAnexus Platform using the command dx describe.

Describing an Object by Name

Objects can be described using their DNAnexus Platform name via the command line interface (CLI) using a path.

Describe an Object With a Relative Path

Objects can be described relative to the user's current directory on the DNAnexus Platform. In the following example, the indexed reference genome file human_g1k_v37.bwa-index.tar.gz is described.

$ dx describe "Original files/human_g1k_v37.bwa-index.tar.gz"
Result 1:
ID                file-xxxx
Class             file
Project           project-xxxx
Folder            /Original files
Name              human_g1k_v37.bwa-index.tar.gz
State             closed
Visibility        visible
Types             -
Properties        -
Tags              -
Outgoing links    -
Created           ----
Created by        Amy
 via the job      job-xxxx
Last modified     ----
archivalState     "live"
Size              3.21 GB

The entire path is enclosed in quotes because the folder name Original files contains whitespace. Instead of quotes, escape special characters with \: dx describe Original\ files/human_g1k_v37.bwa-index.tar.gz.

Describe an Object in a Different Project Using an Absolute Path

Objects can be described using an absolute path. This allows you to describe objects outside the current project context. In the following example, dx select selects the project "My Research Project" and dx describe describes the file human_g1k_v37.fa.gz in the "Reference Genome Files" project.

$ dx select "My Research Project"
$ dx describe Reference\ Genome\ Files:H.\ Sapiens\ -\ GRCh37\ -\ b37\ (1000\ Genomes\ Phase\ I)/human_g1k_v37.fa.gz
Result 1:
ID                file-xxxx
Class             file
Project           project-xxxx
Folder           /H. Sapiens - GRCh37 - b37 (1000 Genomes Phase I)
Name              human_g1k_v37.fa.gz
State             closed
Visibility        visible
Types             -
Properties        -
Tags              -
Outgoing links    -
Created           ----
Created by        Amy
 via the job      job-xxxx
Last modified     ----
archivalState     "live"
Size              810.45 MB

Describe an Object Using Object ID

Objects can be described using a unique object ID.

This example describes the workflow object "Exome Analysis Workflow" using its ID. This workflow is publicly available in the "Exome Analysis Demo" project.

$ dx describe "Exome Analysis Demo":workflow-G409jQQ0bZ46x5GF4GXqKxZ0
Result 1:
ID                  workflow-G409jQQ0bZ46x5GF4GXqKxZ0
Class               workflow
Project             project-BQfgzV80bZ46kf6pBGy00J38
Folder              /
Name                Exome Analysis Workflow
....
Stage 0             bwa_mem_fastq_read_mapper
  Executable        app-bwa_mem_fastq_read_mapper/2.0.1
Stage 1             fastqc
  Executable        app-fastqc/3.0.1
Stage 2             gatk4_bqsr
  Executable        app-gatk4_bqsr_parallel/2.0.1
Stage 3             gatk4_haplotypecaller
  Executable        app-gatk4_haplotypecaller_parallel/2.0.1
Stage 4             gatk4_genotypegvcfs
  Executable        app-gatk4_genotypegvcfs_single_sample_parallel/2.0.0

Because workflows can include many app(let)s, inputs/outputs, and default parameters, the dx describe output can seem overwhelming.

Manipulating Outputs

The output from a dx describe command can be used for multiple purposes. The optional argument --json converts the output from dx describe into JSON format for advanced scripting and command line use.

In this example, the publicly available workflow object "Exome Analysis Workflow" is described and the output is returned in JSON format.

$ dx describe "Exome Analysis Demo":workflow-G409jQQ0bZ46x5GF4GXqKxZ0 --json
  {
    "project": "project-BQfgzV80bZ46kf6pBGy00J38",
    "name": "Exome Analysis Workflow",
    "inputSpec": [
      {
        "name": "bwa_mem_fastq_read_mapper.reads_fastqgzs",
        "class": "array:file",
        "help": "An array of files, in gzipped FASTQ format, with the first read mates to be mapped.",
        "patterns": [ "*.fq.gz", "*.fastq.gz" ],
        ...
      },
      ...
    ],
    "stages": [
      {
        "id": "bwa_mem_fastq_read_mapper",
        "executable": "app-bwa_mem_fastq_read_mapper/2.0.1",
        "input": {
          "genomeindex_targz": {
            "$dnanexus_link": {
              "project": "project-BQpp3Y804Y0xbyG4GJPQ01xv",
              "id": "file-FFJPKp0034KY8f20F6V9yYkk"
            }
          }
        },
        ...
      },
      {
        "id": "fastqc",
        "executable": "app-fastqc/3.0.1",
        ...
      }
      ...
    ]
  }

Parse, process, and query the JSON output using jq. Below, the dx describe --json output is processed to generate a list of all stages in the exome analysis pipeline.

$ dx describe "Exome Analysis Demo":workflow-G409jQQ0bZ46x5GF4GXqKxZ0 --json |jq .stages
[{
    "id": "bwa_mem_fastq_read_mapper",
    "executable": "app-bwa_mem_fastq_read_mapper/2.0.1",
  ...
  }, {
    "id": "fastqc",
    "executable": "app-fastqc/3.0.1",
  ...
  }, {
    "id": "gatk4_bqsr",
    "executable": "app-gatk4_bqsr_parallel/2.0.1",
  ...
  }
  ...
}]

To get the "executable" value of each stage present in the "stages" array value of the dx describe output above, use the following command:

$ dx describe "Exome Analysis Demo":workflow-G409jQQ0bZ46x5GF4GXqKxZ0 --json | jq '.stages | map(.executable) | .[]'
  "app-bwa_mem_fastq_read_mapper/2.0.1"
  "app-fastqc/3.0.1"
  "app-gatk4_bqsr_parallel/2.0.1"
  "app-gatk4_haplotypecaller_parallel/2.0.1"
  "app-gatk4_genotypegvcfs_single_sample_parallel/2.0.0"

General Response Fields Overview

Field name

Objects

Description

All

Unique ID assigned to a DNAnexus object.

Class

All

DNAnexus object type.

Project

All

Container where the object is stored.

Folder

All

Objects inside a container (project) can be organized into folders. Objects can only exist in one path within a project.

Name

All

Object name on the platform.

State

All

Status of the object on the platform.

Visibility

All

Whether the file is visible to the user through the platform web interface.