Exco

Excel Comment ORM. Declare ORM Spec descriptively right on the excel file.

What it does

The package allows you to declare orm mapping right in the excel file in the comments then use it to extract data from other similar files.

An example of a template is shown below.

Dynamic Location, Validation, Assumptions, custom Parser are also supported.

Installation

pip install exco

Simple Usage

import exco
processor = exco.from_excel('./quickstart_template.xlsx')
result = processor.process_excel('./quickstart_data_file.xlsx')
print(result.to_dict())

See Also Quick Start Notebook

Exco Block

Exco relies on yml blocks inside excel comment to build a spec. Each comment can contain multiple blocks. There are three types of echo block: a cell block, a table block, and a column block.

Cell Block

A cellblock is a block of yml that is surrounded by {{-- and --}}

{{--
key: some_int
parser: int
--}}

This means that parse this cell as int and put it in the result with key some_int.

Other advance features like, fallback, locator, assumptions, validator are optional. The full specification is shown below.

{{--
key: some_value
# Optional default at_comment_cell
locator: {name: at_comment_cell} 
assumptions: # Optional
    - {key: right_of, name: right_of, label: marker}
parser: int
# Optional
fallback: 7 
# Optional. Dict[name, value].
params: {} 
validators: # Optional
    - {key: between, name: between, low: 5, high: 10 }
metadata: {unit: km}
--}}

Processing Flow.

The cell processing flow is

1. Locating the Cell
2. Check Assumption
3. Parse
4. Validation

Features

key

Key where the result will be put. This is required.

fallback

This is the most useful one where if the cell is failed locating, testing assumption, parsing. The fallback value is assumed. If it is not specified, the value None is used. (yml's none is null).

locator

Locator is a dictionary. The key name is the class name to be used to locate the cell. Other parameters can be flattened and put in the same dictionary. These parameters will be pass through the constructor of such class.

If the locator is left out, it is assumed to be at_comment_cell which locate the cell with exactly the same coordinate as the commented cell in the template.

assumptions

List of dictionaries. The key is the name of the check. name is the name of the class to be used in testing an assumption. Other parameters can be flattened and included in the same dictionary.

parser

Required. Name of the parser class.

params

Optional. Dictionary of the parameter name to its value. The spread values are passed through the parser constructor.

validations

Optional. List of Dictionary. Each dictionary must have key for the validation key and name, validator's class name, specified. Other parameters to be passed to the validator constructor can be flattened and specified in this dictionary as well.

metadata

Optional. Metadata. Dictionary of any object can be put here. The object will be parsed on to the result.

Table Block

A table block is for specifying the properties of the table. The table block is surrounded by {{--table and --}}. The simplest table block is

{{--table
key: some_table
--}}

This is typically what you need. A more complicated example is shown below:

{{--table
key: some_table
# optional. default at_comment_cell
locator: {name: at_comment_cell}
# optional. default downward
item_direction: downward
end_conditions:
    - {name: all_blank}
    - {name: max_row, n: 10, inclusive: true}
--}}

Features

key

where the table will be put in the result. The output for the table is a list of dictionaries where the key in the dictionaries is the column name specified in column blocks.

locator

Optional. Default at_comment_cell. Locator for the table anchor cell. Same as a cell block.

item_direction

Optional Direction for items in the table. Default downward. (rightward or downward)

end_conditions

A list of dictionary specifying each termination condition. The dictionary contains name and flattened parameters.

If any of the end condition is met then the parsing for the table terminates. Depending on the end condition's class, it may or may not include the matching row.

Column Block

Column block specifications are very similar to the cell block. The simplest example is shown below.

{{--col
table_key: some_table
key: some_col
parser: int
}}

The column block is very similar to the cell block. It is the cell block with table_key and without locator. The table_key tells which table it belongs to. It must match one of the table's key defined in the table block.

The position of the column cell when extracting value is computed from the relative position to the table block in the template.

All other features like fallback, assumptions, validations are also supported in the same fashion as the cell block.

Built-in Functions

Locator

at_comment_cell

Locate the cell right at the comment cell's coordinate in the template.

right_of

Locate the cell to the right of the cell with the given label.

Parameters:

• label label to match.

right_of_regex

Locate the cell to the right of the cell with a regex match.

Parameters:

• regex string for the regular expression.

below_of

Locate the cell below of the cell with the given label.

Parameters:

• label label to match.

Assumption

left_cell_match

This is useful in batch processing allowing us to check that we have the correct label to the left.

Parameters:

• label string to check that it matches.

Parser

string

parse value as string.

int

parse the value as an integer.

float

parse the value as float

date

parser the value as a date.

Validator

between

valid if the value is between(inclusively) high and low

Parameters

• high upper bound value.
• low lower bound value

TableEndCondition

all_blank

Evaluate to true of all columns are blank.

max_row

Evaluate to true if the row number(start from 1) including the parsing row is greater than or equal to n.

Parameters

• n number of row
• inclusive Optional. Default True. Whether to include the row in which it evaluates to true.

Dereferencing

There are two types of dereferencing

• Spec Creation time dereferencing. The string similar to <<A1>> will be resolved to the value at A1 of the template file.
• Extraction time dereferencing. This string similar to ==A1== will be resolved to the value at A1 of the extracted file.

Here is an example

{{--
key: ==D2==
assumptions: # Optional
    - {key: right_of, name: right_of, label: <<A1>>}
parser: int
fallback: ==D3== 
--}}

Handle Identical Sheet with Different Names

When an excel file to be extracted has a different sheet name than the one in the template file, use sheet_name_checkers parameter in exco.from_excel() to create ExcelProcessor with sheet name alias checker.

For example, when the sheet name in the template file is 'Test 1/1/2021', but sheet names can be varied in the extracting files, i.e., 'Test 2/2/2022, 'Test 3/3/2023', etc.

import exco

SheetName = str
SheetNameAliasChecker = Callable[[SheetName], bool]
test_sheet_checker: SheetNameAliasChecker = lambda sheetname: 'Test' in sheetname
checkers: Dict[SheetName, SheetNameAliasChecker] = {'Test 1/1/2021': test_sheet_checker}
processor = exco.from_excel(template_excel_path, sheet_name_checkers=checkers)