Creating xlsx files from xml template using
openpyxl.
This project is intended to create xlsx files from xml api to
openpyxl, supposedly generated by other tamplate engines (i.e. django,
jinja).
This is a merely an xml parser translating mostly linearly to worksheet, rows and finally cells of the Excel workbook.
An xml file like this one
<workbook>
<worksheet title="test">
<row><cell>This</cell><cell>is</cell><cell>a TEST</cell></row>
<row><cell>Nice, isn't it?</cell></row>
</worksheet>
</workbook>can be parsed to create a neat Excel workbook with two rows of data in one worksheet. Parsing can be done using command line (provided that you have your system paths set correctly:
xml2xlsx < input.xml > output.xmlor as a library call
from xml2xlsx import xml2xlsx
template = '<sheet title="test"></sheet>'
f = open('test.xlsx', 'wb')
f.write(xml2xlsx(template))
f.close()This is mainly intended (and was developed for this purpose) to parse files generated by other templating engines, like django template system. One can generate an excel workbook from template like this:
{% for e in list %}
<row><cell>{{ e.name }}</cell></row>
{% endfor %}Basic features of the library include creating multiple, named sheets within one workbook and creating rows of cells in these sheets. However, there are more possibiliteis to create complex excel based reports.
Each cell can be specified to use one of the types:
- string (default)
- number
- date
Type is defined in type cell attribute. The cell value is converted
appropriately to the type specified. If you insert a number in the cell
value and do not specify type="number" attribute, you will find Excel
complaining about storing nubers as text.
Since there are more date formats than countries, you have to be aware
of current locale. The simplest way to be i18n compatible is to specify
date format in date-fmt attribute and pass compatible (possibily non
localized) date in the cell value, as in the following example
...
<row><cell type="date" date-fmt="%Y-%m-%d">2016-10-01</cell></row>
<row><cell type="date" date-fmt="%d.%m.%Y">01.10.2016</cell></row>
...Generated excel file will have two rows with the same date (1st of October 2016) with date formatted according to Excel defaults (and current locale).
::: warning ::: title Warning :::
Excel tries to be very smart and converts date-like text to date format.
Please use type="date" and date-fmt attribute always if you pass
dates to cells.
:::
Columns can be tackled only in a limited way, i.e. only column widths
can be changed. Column properties are defined in columns tag as one or
more child of the sheet tag. It is possible to specify a range of
columns using start and end atrributes. For example:
...
<sheet title="test">
<columns start="A" end="D" width="123"/>
<row><cell>Test</cell></row>
</sheet>
...xml2xls can effectively create cells with formulas in them. The only
limitation (as with openpyxl) is using English names of the functions.
For example:
...
<row><cell>=SUM(A1:A5)</cell></row>
...The parser can store positions of the cell in a dictionary-like
structure. It then can be referenced to create complex formulas. Each
value of the cell is preprocessed using string format with stored
values. This means that these values can be referenced using { and }
brackets.
There are two basic values that can always be used, i.e. row and col
which return current row number and column name.
<workbook>
<sheet>
<row><cell>{col}{row}</cell></row>
</sheet>
</workbook>
...would create a workbook with a text "A1" included in the A1 cell of
the worksheet. Using template languages, you can create more complicated
constructs, like (using django template system):
...
{% for e in list %}
<row>
<cell type="date" date-fmt="%Y-%m-%d">{{ e|date:"Y-m-d" }}</cell>
<cell>=TEXT(A{row}, "ddd")</cell>
</row>
{% endfor %}
...would create a list of rows with a date in the first column and weekday
names for these dates in the second column (provided list context
variable contains a list of dates).
It is also possible to store cell possible to store names of specified
cells in a pseudo-variable (as in a dictionary). One has to use ref-id
attribute of the cell tag and then reuse the value of this attribute
in the remainder of the xml input. This is very useful in formulas. A
simple example would be referencing another cell in a formula like this:
...
<row><cell ref-id="mycell">This is just a test</cell></row>
...
<row><cell>={mycell}</cell></row>
...which would create an excel formula referencing a cell with "this is just a test" text, whatever this cell address was.
::: warning ::: title Warning :::
Using the same identifier in ref-id attribute for two different cells
overwrites the cell reference, i.e. the last cell in the xml
template would be referenced.
:::
A more complex example using django template engine to create summaries can look like this:
...
{% for e in list %}
<row>
<cell ref-id="{% if forloop.first %}start{% elsif forloop.last %}end{% endif %}">
{{ e }}
</cell>
</row>
{% endfor %}
<row>
<cell>Summary</cell>
<cell>=SUM({start}:{end})</cell>
</row>
...Referencing a single cell can be harsh when dealing with complex
reports. Especially when creating summaries of irregularly
sheet-distributed data. xml2xlsx can append a cell to a variable-like
list, as in ref-id attribute, to reuse it as a comma concatenated
value. Instead of ref-id, one has to use ref-append attribute.
This is a simple example to demonstrate the feature:
...
<sheet>
<row>
<cell ref-append="mylist">1</cell>
<cell ref-append="mylist">2</cell>
</row>
<row><cell ref-append="mylist">3</cell></row>
<row><cell>=SUM({mylist})</cell></row>
</sheet>This will generate an Excel sheet with A3 cell containing formula to
sum A1, B1 and A2 cells (=SUM(A1, B1, A2)).
It is perfectly possible to reference a cell in another sheet with both
ref-id and ref-append. However, there is a limitation to that. Since
xml2xslx is a linear parser, you are only allowed to reference already
parsed elements. This means, you have to create sheets in a proper order
(sheets referencing other sheets must be created after referenced
cells are parsed).
The following example will not work:
...
<sheet title="one">
<row><cell>{mycell}</cell></row>
</sheet>
<sheet title="two">
<row><cell ref-id="mycell">XYZ</cell></row>
</sheet>
...However, it is possible to make this exmaple work and retain the
same worksheet ordering using index attribute:
...
<sheet title="two">
<row><cell ref-id="mycell">XYZ</cell></row>
</sheet>
<sheet title="one" index="0">
<row><cell>{mycell}</cell></row>
</sheet>
...The cell format can be specified using various attributes of the cell tag. Only font formatting can be specifed for now.
A font format is specified in in font attribute. It is a semicolon
separated dict like list of font formats as specified in
font
class of openpyxl library.
An example to create a cell with bold 10px font:
...
<cell font="bold: True; size: 10px;">Cell formatted</cell>
...
Here is the (probably incomplete) wishlist for the project
- Global font and cell styles
- Row widths and column heights
- Horizontal and vertical cell merging
- XML validation with XSD to quickly raise an error if parsing wrong xml
Parsed xml should be enclosed in a workbook tag. Each workbook tag
can have multiple sheet. The hierarchy continues to row and cell
tags.
Here is a complete list of available attributes of these tags.
No attributes for now.
Attribute
: title
Usage
: Specifies the worksheet title
Attribute
: index
Usage
: Specifies the worksheet index. This is relative to already created indexes. An index of 0 creates sheet at the beginning of the sheets collection.
No attributes for now
Attribute
: start
Usage
: Specifies the starting column for the column range (in a letter format).
Attribute
: end
Usage
: Specifies the ending column for the column range (in a letter format).
Default
: Same as start attribute
Attribute
: width
Usage
: Specifies the width for all columns in the range. It is in px format.
Attribute
: type
Usage
: Specifies the resulting type of the excel cell.
Type
: One of unicode, date, number
Default
: unicode
Attribute
: date-fmt
Usage
: Specifies the format of the date parsed as in strftime and
strptime
functions of datetime standard python library.
Remarks
: Parsed only if type="date".
Attribute
: font
Usage
: Sepcifies font formatting for a single cell.
Type
: List of semicolon separated dict-like values in form of
key: value; key: value;
Remarks
: Key and values are arguments of Font clas in openpyxl.
- Added documentation
- Added cell referencing with inter-sheet possibility
- Changed
sheettitle attribute fromnametotitle - Added possibility to set index for a sheet