# Define projections

Completed

The projections of data to be stored in your knowledge store are based on the document structures generated by the enrichment pipeline in your indexing process. Each skill in your skillset iteratively builds a JSON representation of the enriched data for the documents being indexed, and you can persist some or all of the fields in the document as projections.

## Using the Shaper skill

The process of indexing incrementally creates a complex document that contains the various output fields from the skills in the skillset. This can result in a schema that is difficult to work with, and which includes collections of primitive data values that don't map easily to well-formed JSON.

To simplify the mapping of these field values to projections in a knowledge store, it's common to use the Shaper skill to create a new, field containing a simpler structure for the fields you want to map to projections.

For example, consider the following Shaper skill definition:

{
"@odata.type": "#Microsoft.Skills.Util.ShaperSkill",
"name": "define-projection",
"description": "Prepare projection fields",
"context": "/document",
"inputs": [
{
"name": "file_name",
},
{
"name": "url",
"source": "/document/url"
},
{
"name": "sentiment",
"source": "/document/sentimentScore"
},
{
"name": "key_phrases",
"source": null,
"sourceContext": "/document/merged_content/keyphrases/*",
"inputs": [
{
"name": "phrase",
"source": "/document/merged_content/keyphrases/*"
}
]
}
],
"outputs": [
{
"name": "output",
"targetName": "projection"
}
]
}


This Shaper skill creates a projection field with the following structure:

{
"file_name": "file_name.pdf",
"url": "https://<storage_path>/file_name.pdf",
"sentiment": 1.0,
"key_phrases": [
{
"phrase": "first key phrase"
},
{
"phrase": "second key phrase"
},
{
"phrase": "third key phrase"
},
...
]
}


The resulting JSON document is well-formed, and easier to map to a projection in a knowledge store than the more complex document that has been built iteratively by the previous skills in the enrichment pipeline.