X-Git-Url: https://git.openstreetmap.org./nominatim.git/blobdiff_plain/ef1b52eee517d826c7c0e664f9a539b8ceffaaf6..2c0f2e1eded166fa27471bc640420713a2bb964f:/docs/library/Getting-Started.md diff --git a/docs/library/Getting-Started.md b/docs/library/Getting-Started.md index 77724e67..9f81724a 100644 --- a/docs/library/Getting-Started.md +++ b/docs/library/Getting-Started.md @@ -1,77 +1,76 @@ # Getting Started -The Nominatim search frontend can directly be used as a Python library in -scripts and applications. When you have imported your own Nominatim database, -then it is no longer necessary to run a full web service for it and access -the database through http requests. With the Nominatim library it is possible -to access all search functionality directly from your Python code. There are -also less constraints on the kinds of data that can be accessed. The library -allows to get access to more detailed information about the objects saved -in the database. - -!!! danger - The library interface is currently in an experimental stage. There might - be some smaller adjustments to the public interface until the next version. - - The library also misses a proper installation routine, so some manipulation - of the PYTHONPATH is required. Use is only recommended for advanced Python - programmers at the moment. +The Nominatim search frontend is implemented as a Python library and can as +such directly be used in Python scripts and applications. You don't need to +set up a web frontend and access it through HTTP calls. The library gives +direct access to the Nominatim database through similar search functions as +offered by the web API. In addition, it will give you a more complete and +detailed view on the search objects stored in the database. + +!!! warning + + The Nominatim library is used for accessing a local Nominatim database. + It is not meant to be used against web services of Nominatim like the + one on https://nominatim.openstreetmap.org. If you need a Python library + to access these web services, have a look at + [GeoPy](https://geopy.readthedocs.io). Don't forget to consult the + usage policy of the service you want to use before accessing such + a web service. ## Installation To use the Nominatim library, you need access to a local Nominatim database. -Follow the [installation and import instructions](../admin/) to set up your -database. +Follow the [installation](../admin/Installation.md) and +[import](../admin/Import.md) instructions to set up your database. -It is not yet possible to install it in the usual way via pip or inside a -virtualenv. To get access to the library you need to set an appropriate -PYTHONPATH. With the default installation, the python library can be found -under `/usr/local/share/nominatim/lib-python`. If you have installed -Nominatim under a different prefix, adapt the `/usr/local/` part accordingly. -You can also point the PYTHONPATH to the Nominatim source code. +The Nominatim frontend library is contained in the Python package `nominatim-api`. +You can install the latest released version directly from pip: -### A simple search example + pip install nominatim-api + +To install the package from the source tree directly, run: + + pip install packaging/nominatim-api + +Usually you would want to run this in a virtual environment. + +## A simple search example To query the Nominatim database you need to first set up a connection. This is done by creating an Nominatim API object. This object exposes all the search functions of Nominatim that are also known from its web API. -This code snippet implements a simple search for the town if 'Brugge': +This code snippet implements a simple search for the town of 'Brugge': !!! example === "NominatimAPIAsync" ``` python - from pathlib import Path import asyncio - import nominatim.api as napi + import nominatim_api as napi async def search(query): - api = napi.NominatimAPIAsync(Path('.')) - - return await api.search(query) + async with napi.NominatimAPIAsync() as api: + return await api.search(query) results = asyncio.run(search('Brugge')) if not results: print('Cannot find Brugge') else: - print(f'Found a place at {results[0].centroid.x},{results[1].centroid.y}') + print(f'Found a place at {results[0].centroid.x},{results[0].centroid.y}') ``` === "NominatimAPI" ``` python - from pathlib import Path - - import nominatim.api as napi + import nominatim_api as napi - api = napi.NominatimAPI(Path('.')) - - results = api.search('Brugge') + with napi.NominatimAPI() as api: + results = api.search('Brugge') if not results: print('Cannot find Brugge') else: - print(f'Found a place at {results[0].centroid.x},{results[1].centroid.y}') + print(f'Found a place at {results[0].centroid.x},{results[0].centroid.y}') ``` The Nominatim library is designed around @@ -83,13 +82,13 @@ significantly. For smaller scripts there is also a synchronous wrapper around the API. By using `NominatimAPI`, you get exactly the same interface using classic functions. -The examples in this chapter will always show how work with both of the -implementations. The documentation itself will refer usually only to +The examples in this chapter will always show-case both +implementations. The documentation itself will usually refer only to 'Nominatim API class' when both flavours are meant. If a functionality is available only for the synchronous or asynchronous version, this will be explicitly mentioned. -### Defining which database to use +## Defining which database to use The [Configuration](../admin/Import.md#configuration-setup-in-env) section explains how Nominatim is configured using the @@ -98,76 +97,120 @@ The same configuration mechanism is used with the Nominatim API library. You should therefore be sure you are familiar with the section. -The constructor of the 'Nominatim API class' takes one mandatory parameter: -the path to the [project directory](../admin/Import.md#creating-the-project-directory). -You should have set up this directory as part of the Nominatim import. -Any configuration found in the `.env` file in this directory will automatically -used. +There are three different ways, how configuration options can be set for +a 'Nominatim API class'. When you have set up your Nominatim database, you +have normally created a [project directory](../admin/Import.md#creating-the-project-directory) +which stores the various configuration and customization files that Nominatim +needs. You may pass the location of the project directory to your +'Nominatim API class' constructor and it will read the .env file in the +directory and set the configuration accordingly. Here is the simple search +example, using the configuration from a pre-defined project directory in +`/srv/nominatim-project`: + +!!! example + === "NominatimAPIAsync" + ``` python + import asyncio + + import nominatim_api as napi -The second way to configure your Nominatim setup is through environment variables. -Normally, Nominatim will check the operating system environment. This can be -overwritten by giving the constructor a dictionary of configuration parameters. + async def search(query): + async with napi.NominatimAPIAsync('/srv/nominatim-project') as api: + return await api.search(query) -Let us look up 'Brugge' in the special database named 'belgium' instead of the -standard 'nominatim' database: + results = asyncio.run(search('Brugge')) + if not results: + print('Cannot find Brugge') + else: + print(f'Found a place at {results[0].centroid.x},{results[0].centroid.y}') + ``` + + === "NominatimAPI" + ``` python + import nominatim_api as napi + + with napi.NominatimAPI('/srv/nominatim-project') as api: + results = api.search('Brugge') + + if not results: + print('Cannot find Brugge') + else: + print(f'Found a place at {results[0].centroid.x},{results[0].centroid.y}') + ``` + + +You may also configure Nominatim by setting environment variables. +Normally Nominatim will check the operating system environment. Lets +say you want to look up 'Brugge' in the special database named 'belgium' instead of the +standard 'nominatim' database. You can run the example script above like this: + +``` +NOMINATIM_DATABASE_DSN=pgsql:dbname=belgium python3 example.py +``` + +The third option to configure the library is to hand in the configuration +parameters into the 'Nominatim API class'. Changing the database would look +like this: !!! example === "NominatimAPIAsync" ``` python - from pathlib import Path import asyncio - - import nominatim.api as napi + import nominatim_api as napi config_params = { 'NOMINATIM_DATABASE_DSN': 'pgsql:dbname=belgium' } async def search(query): - api = napi.NominatimAPIAsync(Path('.'), environ=config_params) - - return await api.search(query) + async with napi.NominatimAPIAsync(environ=config_params) as api: + return await api.search(query) results = asyncio.run(search('Brugge')) ``` === "NominatimAPI" ``` python - from pathlib import Path - - import nominatim.api as napi + import nominatim_api as napi config_params = { 'NOMINATIM_DATABASE_DSN': 'pgsql:dbname=belgium' } - api = napi.NominatimAPI(Path('.'), environ=config_params) - - results = api.search('Brugge') + with napi.NominatimAPI(environ=config_params) as api: + results = api.search('Brugge') ``` -### Presenting results to humans +When the `environ` parameter is given, then only configuration variables +from this dictionary will be used. The operating system's environment +variables will be ignored. -All search functions return the raw results from the database. There is no -full human-readable label. To create such a label, you need two things: +## Presenting results to humans + +All search functions return full result objects from the database. Such a +result object contains lots of details: names, address information, OSM tags etc. +This gives you lots of flexibility what to do with the results. + +One of the most common things to get is some kind of human-readable label +that describes the result in a compact form. Usually this would be the name +of the object and some parts of the address to explain where in the world +it is. To create such a label, you need two things: * the address details of the place -* adapt the result to the language you wish to use for display +* all names for the label adapted to the language you wish to use for display Again searching for 'Brugge', this time with a nicely formatted result: !!! example === "NominatimAPIAsync" ``` python - from pathlib import Path import asyncio - import nominatim.api as napi + import nominatim_api as napi async def search(query): - api = napi.NominatimAPIAsync(Path('.')) - - return await api.search(query, address_details=True) + async with napi.NominatimAPIAsync() as api: + return await api.search(query, address_details=True) results = asyncio.run(search('Brugge')) @@ -179,13 +222,10 @@ Again searching for 'Brugge', this time with a nicely formatted result: === "NominatimAPI" ``` python - from pathlib import Path - - import nominatim.api as napi - - api = napi.NominatimAPI(Path('.')) + import nominatim_api as napi - results = api.search('Brugge', address_details=True) + with napi.NominatimAPI() as api: + results = api.search('Brugge', address_details=True) locale = napi.Locales(['fr', 'en']) for i, result in enumerate(results): @@ -209,8 +249,8 @@ results should be presented. As with the names in the result itself, the places in `address_rows` contain all possible name translation for each row. The library has a helper class `Locale` which helps extracting a name of a -place in the preferred language. It gets a list of language code in the -order of preference. So +place in the preferred language. It takes a single parameter with a list +of language codes in the order of preference. So ``` python locale = napi.Locale(['fr', 'en']) @@ -220,7 +260,7 @@ creates a helper class that returns the name preferably in French. If that is not possible, it tries English and eventually falls back to the default `name` or `ref`. -The Locale object can be applied to a name dictionary to return the best-matching +The `Locale` object can be applied to a name dictionary to return the best-matching name out of it: ``` python @@ -241,7 +281,7 @@ Bruges, Flandre-Occidentale, Flandre, Belgique This is a fairly simple way to create a human-readable description. The place information in `address_rows` contains further information about each -place. For example, which OSM `adlin_level` was used, what category the place +place. For example, which OSM `admin_level` was used, what category the place belongs to or what rank Nominatim has assigned. Use this to adapt the output to local address formats.