1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
.. _binary:
=============
Binary data
=============
SQLite tables can contain binary data in ``BLOB`` columns.
Datasette includes special handling for these binary values. The Datasette interface detects binary values and provides a link to download their content, for example on https://latest.datasette.io/fixtures/binary_data
`Screenshot showing download links next to binary data in the table view <https://raw.githubusercontent.com/simonw/datasette-screenshots/0.62/binary-data.png>`__
Binary data is represented in ``.json`` exports using Base64 encoding.
https://latest.datasette.io/fixtures/binary_data.json?_shape=array
.. code-block:: json
[
{
"rowid": 1,
"data": {
"$base64": true,
"encoded": "FRwCx60F/g=="
}
},
{
"rowid": 2,
"data": {
"$base64": true,
"encoded": "FRwDx60F/g=="
}
},
{
"rowid": 3,
"data": null
}
]
.. _binary_linking:
Linking to binary downloads
---------------------------
The ``.blob`` output format is used to return binary data. It requires a ``_blob_column=`` query string argument specifying which BLOB column should be downloaded, for example:
https://latest.datasette.io/fixtures/binary_data/1.blob?_blob_column=data
This output format can also be used to return binary data from an arbitrary SQL query. Since such queries do not specify an exact row, an additional ``?_blob_hash=`` parameter can be used to specify the SHA-256 hash of the value that is being linked to.
Consider the query ``select data from binary_data`` - `demonstrated here <https://latest.datasette.io/fixtures?sql=select+data+from+binary_data>`__.
That page links to the binary value downloads. Those links look like this:
https://latest.datasette.io/fixtures.blob?sql=select+data+from+binary_data&_blob_column=data&_blob_hash=f3088978da8f9aea479ffc7f631370b968d2e855eeb172bea7f6c7a04262bb6d
These ``.blob`` links are also returned in the ``.csv`` exports Datasette provides for binary tables and queries, since the CSV format does not have a mechanism for representing binary data.
Binary plugins
--------------
Several Datasette plugins are available that change the way Datasette treats binary data.
- `datasette-render-binary <https://github.com/simonw/datasette-render-binary>`__ modifies Datasette's default interface to show an automatic guess at what type of binary data is being stored, along with a visual representation of the binary value that displays ASCII strings directly in the interface.
- `datasette-render-images <https://github.com/simonw/datasette-render-images>`__ detects common image formats and renders them as images directly in the Datasette interface.
- `datasette-media <https://github.com/simonw/datasette-media>`__ allows Datasette interfaces to be configured to serve binary files from configured SQL queries, and includes the ability to resize images directly before serving them.
|
