====== Data Operation - Define ======


===== Define =====
''define'' is an [[op|operation]] that defines a [[docs:resource:resource|data resource]].


A [[select|select operation]] may not return any [[docs:resource:resource|data resources]] but the ''define'' operation returns always the data resource that it defines.

This operation is used:
  * to define inline data resource in a [[docs:flow:pipeline|pipeline file]]
  * before a [[create|create]] or [[fill|fill]] operation that will create data resource






===== Arguments =====
The ''define'' operations accept the following arguments.

^ Arguments ^ Mandatory ^ Definition ^
| ''data-uri'' | only if ''data'' is not defined | The [[docs:resource:data_uri|data uri]] is the location of the resource |
| ''data'' | only if ''data-uri'' is not defined | The ''data'' as a list of [[docs:resource:record|records]] (the data are in the inline) |
| ''data-definition'' | no | The [[docs:resource:data-definition|data definition]] |
| ''data-resources'' | | to define more than one data resource (a list of inline data resources) |

===== Usage =====
This operation is only available as [[docs:flow:step|step]] in a [[docs:flow:pipeline|pipeline pipeline]] (ie not in a [[docs:tabli:data:start|tabli data command]])


This is a first step (known as the [[docs:flow:supplier|supplier step]]) because it supplies [[docs:resource:resource|data resources]] to the others operations in the pipeline.


==== Single Data Resource ====

Example: A ''color'' data resource with two columns and 3 records.

<unit>
<file yaml pipeline/define_single.yml>
pipeline:
  - name: "Define"
    comment: "This operation define the tabular data resource named 'colors' with two columns"
    operation: "define"
    args:
      data-resource:
        data-definition:
          logicalName: "colors"
          columns: ["id","color"]
        data:
          - ["1", "blue"]
          - ["2", "red"]
          - ["3", "yellow"]
  - name: "Print"
    comment: "Print the colors resource"
    operation: "print"

</file>
If you [[docs:tabli:flow:execute|execute this pipeline]]
<code bash>
tabli flow execute pipeline/define_single.yml@howto
</code>
you will get the data of the ''colors'' data resource [[docs:tabli:data:print|printed]] in a tabular format.
<console>
id   color
--   ------
1    blue
2    red
3    yellow
</console>
</unit>
==== Multiple Inline Data Resources ====

Two inline data resources ''colors'' and ''characters''
<code yaml>
pipeline:
  - name: 'Define'
    operation: 'define'
    args:
      data-resources:
        - data-definition:
            logicalName: "colors"
            columns: ["id","color"]
          data:
            - ["1", "blue"]
            - ["2", "red"]
            - ["3", "yellow"]
        - data-definition:
            logicalName: "characters"
            columns:
              - name: "id"
                type: integer
              - name: "name"
              - name: "last_name"
          data:
            - [1, "Arnold","Schwarzy"]
            - [2, "Don","Norman"]
            - [3, "Dale","Carnegie"]
            - [4, "Daniel","Kahneman"]
</code>