---
title: "Config Layer"
slug: "config-layer-syntax"
updated: 2022-07-27T20:33:10Z
published: 2022-07-27T20:33:10Z
canonical: "code.tag.bio/config-layer-syntax"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://code.tag.bio/llms.txt
> Use this file to discover all available pages before exploring further.

# Config Layer

**Parsers** are the workhorses of the data configuration layer.

A typical Data Product will employ between 10 and 100 **parsers** to design & generate the `collections` and `variables` within its data model.

In order to function, **parsers** must be registered either from the *parsers* attribute in the **config** file or from the *parsers* attribute of a **table** object.

Each **parser** is affiliated with a single **table** object, and will only operate on the source data defined by that **table** object.

## naming convention

All **parsers** for a given **table** object are typically combined into single text file, formatted as a JSON array. The file is conventionally named `mytablealias_parsers.json`, where you replace *mytablealias* with the value of the *table_alias* attribute for the **table** object.

Each **parsers** array file is conventionally located in the Data Product directory path `config/parsers/mytablealias_parsers.json`.

## a few more details

During the Tag.bio data ingestion process, each **table** object will be initialized and then proceed to load all rows from its source data table, one row at a time. The **parsers** assigned to each **table** object will capture values from some of those rows and columns and convert them into `collections` and `variables` in the Data Product.

**Parsers**, as peer elments within a JSON array, are designed to be completely indpendent from each other - i.e. none of the **parsers** listed in the *parsers* array for a **table** object will cross-communicate. With this design, **parsers** can be added, removed, or updated without impacting the behavior of any peer **parsers**. This pattern also enables multithread parallelization of data parsing over both rows and columns.

In contrast to above, indiviual **parsers** are allowed to - and often expected to - utilize inner **parsers** nested within the bounds of their own JSON specification. As each row is processed from source data, the inner **parsers** will pipe their output to provide specific attribute values to their parent **parser**. This pattern enables a wide variety of conditional behavior and useful data transformations with multiple **parsers** combining to form a complex data loading function.

## variety

There are around 40 different types of **parser** available within the Tag.bio system, although two specific types - `categorical` and `numeric` - comprise about 80% of the **parsers** utilized across all Data Products to date.

Some **parsers** will only load small amounts of data from the source table compared to other **parsers**. For example, the `categorical` and `numeric` **parser** types typically load data from only one column of a source data table, while the `numeric-matrix` **parser** type can easily be configured to ingest all rows and columns into a single `numeric-matrix` `variable`.