Postcode Geocode Demo

A simple go demo web-application for to look up a UK postcode from a database and mark the location on the map.

Dependencies

• go1.21.6
• make
• staticcheck

Retrieving the data

The importer assumes that the postcode data is in CSV files. The CSV files will have 3 columns, and they should not have a header.

i.e.

Postcode	Lat	Lng
ZZ99 9ZZ	0	0

This data can be obtained by using the postcode coordinate converter for the Ordnance Survey Codepoint Open dataset:

https://github.com/silktown-software/postcode-coordinate-converter

Importer Usage

First run the importer to build the postcode database:

$ make build-importer
$ ./dist/importer/postcode-importer -h
Usage of ./dist/importer/postcode-importer:
  -directory string
        the directory that contains the CSV files to import

e.g.

If you run the importer in the root of the source directory:

$ ./dist/importer/postcode-importer -directory=<directory with CSV files>

You can verify if the importer has worked correctly by comparing the total count of lines in the CSV file with the total row count in the postcode table:

$ find . -name '*.csv' -type f -exec cat {} + | wc -l
1736857

If you connect to the sqlite database:

$ sqlite3 postcodes.db 
SQLite version 3.40.1 2022-12-28 14:03:47
Enter ".help" for usage hints.
sqlite> select count(*) from postcode;
1736857

Running the demo web-application

$ go run cmd/demo/main.go

By default, it will run on PORT 5000. You can specify an alternative port via an environment variable.

It will expect the postcodes.db file to be in the root of the repository if running it via go run cmd/demo/main.go.

TODO:

• Split the importer logic into separate package.
• Change Lat/Lng column order, so it is Lng/Lat. Lng/Lat is the preferred order.
• Write batch insert test.