---
title: "Parsers"
slug: "parsers"
updated: 2022-12-13T00:03:20Z
published: 2022-12-13T00:03:20Z
canonical: "code.tag.bio/parsers"
---

> ## 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.

# Parsers

## parser_type

**usage: *required*** The *parser_type* tells the Tag.bio system how to instantiate a data loading function. There are 40+ options for `parser_type`. The most commonly used are `categorical` and `numeric`, which share their designation with the two primary data types represented within the Tag.bio system.

```
{
  "parser_type": "ptpt", 
  ...
}
```

## table_alias

**usage: *required*** The `table_alias` attribute tells the system how to assign this **parser** to a **table** object as a data loading function for its source data table.

```
{
  "parser_type": "ptpt",
  "table_alias": "tata",
  ...
}
```

## collection

**usage: *required*** The `collection` attribute will rename the data processed by a parser to something more useful and human-readable. It is best practice to create legible names, but, if a `collection` is not specified, the `collection` name will be automatically assigned the `column` name.

```
{
  "parser_type": "ptpt",
  "table_alias": "tata",
  "column": "cccc",
  "collection": "ccc1"
}
```

## nesting a parser

It's possible to specify an inner **parser** as the value of the `collection` or `variable` attributes. Doing so will define the `collection` or `variable` names by values in a different column.

```
{
  "parser_type": "ptpt",
  "table_alias": "tata",
  "column": "cccc",
  "collection": {
    "parser_type": "ptpt",
    "column": "ccc1"
  }
}
```

```
{
  "parser_type": "ptpt",
  "table_alias": "tata",
  "column": "cccc",
  "collection": "ccc1",
  "variable": {
    "parser_type": "ptpt",
    "column": "ccc2"
  }
}
```

## where

**usage: *optional*** The `where` utilizes a conditional parser to determine which rows should be processed by the parent parser.

Rows that fail to evaluate as **true** will be ignored.

```
{
  "parser_type": "ptpt",
  "table_alias": "tata"
  "where": {
    "parser_type": "categorical-match",
    "column": "city",
    "operator": "=",
    "value": "San Francisco"
  },
  ...
}
```

## null_indicators

**usage: *optional*** The `null_indicators` attribute will specify which values, if found in the source data, will be considered as null.

Values in the array can be `categorical` or `numeric`.

```
{
  "parser_type": "ptpt",
  "table_alias": "tata",
  "column": "cccc",
  "collection": "ccc1",
  "null_indicators": [
    "iiii",
    ####
  ]
}
```

## null_value

**usage: *optional*** This `null_value` attribute is used to replace any null values with a `categorical`, `numeric`, or nested parser you specify.

```
{
  "parser_type": "tttt",
  "table_alias": "tata",
  "column": "cccc",
  "collection": "ccc1",
  "null_indicators": [
    "iiii",
    ####
  ],
  "null_value": "unavailable"
}
```

## annotation

**usage: *optional*** The `annotation` will specify an array of inner parsers which will parse other columns to annotate the variables generated by the parent parser.

```
{
{
  "parser_type": "tttt",
  "table_alias": "tata",
  "column": "cccc",
  "collection": "ccc1",
  "annotation": {
    "parser_type": "tttt",
    "column": "ccc2"
  }
}
}
```

## groups

**usage: *optional*** When `groups` is specified, it will indicate to the system that all `collections` and `variables` produced by the parser will only be accessible for authorized user groups.

```
{
  "parser_type": "tttt",
  "table_alias": "tata",
  "column": "cccc",
  "collection": "ccc1",
  "groups": [
    "admin"
  ]
}
```