Merge pull request #3333 from lonvia/set-empty-extratags-to-null

[nominatim.git] / docs / api / Search.md

# Search queries

The search API allows you to look up a location from a textual description
or address. Nominatim supports structured and free-form search queries.

The search query may also contain
[special phrases](https://wiki.openstreetmap.org/wiki/Nominatim/Special_Phrases)
which are translated into specific OpenStreetMap (OSM) tags (e.g. Pub => `amenity=pub`).
This can be used to narrow down the kind of objects to be returned.

!!! note
    Special phrases are not suitable to query all objects of a certain type in an
    area. Nominatim will always just return a collection of the best matches. To
    download OSM data by object type, use the [Overpass API](https://overpass-api.de/).

## Endpoint

The search API has the following format:

```
   https://nominatim.openstreetmap.org/search?<params>
```

!!! danger "Deprecation warning"
    The API can also be used with the URL
    `https://nominatim.openstreetmap.org/search.php`. This is now deprecated
    and will be removed in future versions.

The query term can be given in two different forms: free-form or structured.

### Free-form query

| Parameter | Value |
|-----------| ----- |
| q         | Free-form query string to search for |

In this form, the query can be unstructured.
Free-form queries are processed first left-to-right and then right-to-left if that fails. So you may search for
[pilkington avenue, birmingham](https://nominatim.openstreetmap.org/search?q=pilkington+avenue,birmingham) as well as for
[birmingham, pilkington avenue](https://nominatim.openstreetmap.org/search?q=birmingham,+pilkington+avenue).
Commas are optional, but improve performance by reducing the complexity of the search.

The free-form may also contain special phrases to describe the type of
place to be returned or a coordinate to search close to a position.

### Structured query

| Parameter  | Value |
|----------- | ----- |
| amenity    | name and/or type of POI |
| street     | housenumber and streetname |
| city       | city |
| county     | county |
| state      | state |
| country    | country |
| postalcode | postal code |

The structured form of the search query allows to lookup up an address
that is already split into its components. Each parameter represents a field
of the address. All parameters are optional. You should only use the ones
that are relevant for the address you want to geocode.

!!! Attention
    Cannot be combined with the `q=<query>` parameter. Newer versions of
    the API will return an error if you do so. Older versions simply return
    unexpected results.

## Parameters

The following parameters can be used to further restrict the search and
change the output. They are usable for both forms of the search query.

### Output format

| Parameter | Value | Default |
|-----------| ----- | ------- |
| format    | one of: `xml`, `json`, `jsonv2`, `geojson`, `geocodejson` | `jsonv2` |

See [Place Output Formats](Output.md) for details on each format.

!!! note
    The Nominatim service at
    [https://nominatim.openstreetmap.org](https://nominatim.openstreetmap.org)
    has a different default behaviour for historical reasons. When the
    `format` parameter is omitted, the request will be forwarded to the Web UI.


| Parameter | Value | Default |
|-----------| ----- | ------- |
| json_callback | function name | _unset_ |

When given, then JSON output will be wrapped in a callback function with
the given name. See [JSONP](https://en.wikipedia.org/wiki/JSONP) for more
information.

Only has an effect for JSON output formats.

| Parameter | Value | Default |
|-----------| ----- | ------- |
| limit     | number | 10 |

Limit the maximum number of returned results. Cannot be more than 40.
Nominatim may decide to return less results than given, if additional
results do not sufficiently match the query.


### Output details

| Parameter | Value | Default |
|-----------| ----- | ------- |
| addressdetails | 0 or 1 | 0 |

When set to 1, include a breakdown of the address into elements.
The exact content of the address breakdown depends on the output format.

!!! tip
    If you are interested in a stable classification of address categories
    (suburb, city, state, etc), have a look at the `geocodejson` format.
    All other formats return classifications according to OSM tagging.
    There is a much larger set of categories and they are not always consistent,
    which makes them very hard to work with.


| Parameter | Value | Default |
|-----------| ----- | ------- |
| extratags | 0 or 1 | 0 |

When set to 1, the response include any additional information in the result
that is available in the database, e.g. wikipedia link, opening hours.


| Parameter | Value | Default |
|-----------| ----- | ------- |
| namedetails | 0 or 1 | 0 |

When set to 1, include a full list of names for the result. These may include
language variants, older names, references and brand.


### Language of results

| Parameter | Value | Default |
|-----------| ----- | ------- |
| accept-language | browser language string | content of "Accept-Language" HTTP header |

Preferred language order for showing search results. This may either be
a simple comma-separated list of language codes or have the same format
as the ["Accept-Language" HTTP header](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Language).

!!! tip
    First-time users of Nominatim tend to be confused that they get different
    results when using Nominatim in the browser versus in a command-line tool
    like wget or curl. The command-line tools
    usually don't send any Accept-Language header, prompting Nominatim
    to show results in the local language. Browsers on the contratry always
    send the currently chosen browser language.

### Result restriction

There are two ways to influence the results. *Filters* exclude certain
kinds of results completely. *Boost parameters* only change the order of the
results and thus give a preference to some results over others.

| Parameter | Value | Default |
|-----------| ----- | ------- |
| countrycodes | comma-separated list of country codes | _unset_ |

Filer that limits the search results to one or more countries.
The country code must be the
[ISO 3166-1alpha2](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) code
of the country, e.g. `gb` for the United Kingdom, `de` for Germany.

Each place in Nominatim is assigned to one country code based
on OSM country boundaries. In rare cases a place may not be in any country
at all, for example, when it is in international waters. These places are
also excluded when the filter is set.

!!! Note
    This parameter should not be confused with the 'country' parameter of
    the structured query. The 'country' parameter contains a search term
    and will be handled with some fuzziness. The `countrycodes` parameter
    is a hard filter and as such should be prefered. Having both parameters
    in the same query will work. If the parameters contradict each other,
    the search will come up empty.

| Parameter | Value | Default |
|-----------| ----- | ------- |
| layer     | comma-separated list of: `address`, `poi`, `railway`, `natural`, `manmade` | _unset_ (no restriction) |

**`[Python-only]`**

The layer filter allows to select places by themes.

The `address` layer contains all places that make up an address:
address points with house numbers, streets, inhabited places (suburbs, villages,
cities, states tec.) and administrative boundaries.

The `poi` layer selects all point of interest. This includes classic POIs like
restaurants, shops, hotels but also less obvious features like recycling bins,
guideposts or benches.

The `railway` layer includes railway infrastructure like tracks.
Note that in Nominatim's standard configuration, only very few railway
features are imported into the database.

The `natural` layer collects feautures like rivers, lakes and mountains while
the `manmade` layer functions as a catch-all for features not covered by the
other layers.

| Parameter | Value | Default |
|-----------| ----- | ------- |
| featureType | one of: `country`, `state`, `city`, `settlement` | _unset_ |

The featureType allows to have a more fine-grained selection for places
from the address layer. Results can be restricted to places that make up
the 'state', 'country' or 'city' part of an address. A featureType of
settlement selects any human inhabited feature from 'state' down to
'neighbourhood'.

When featureType ist set, then results are automatically restricted
to the address layer (see above).

!!! tip
    Instead of using the featureType filters `country`, `state` or `city`,
    you can also use a structured query without the finer-grained parameters
    amenity or street.

| Parameter | Value | Default |
|-----------| ----- | ------- |
| exclude_place_ids | comma-separeted list of place ids |

If you do not want certain OSM objects to appear in the search
result, give a comma separated list of the `place_id`s you want to skip.
This can be used to retrieve additional search results. For example, if a
previous query only returned a few results, then including those here would
cause the search to return other, less accurate, matches (if possible).

| Parameter | Value | Default |
|-----------| ----- | ------- |
| viewbox   | `<x1>,<y1>,<x2>,<y2>` | _unset_ |

Boost parameter which focuses the search on the given area.
Any two corner points of the box are accepted as long as they make a proper
box. `x` is longitude, `y` is latitude.

| Parameter | Value  | Default |
|-----------| -----  | ------- |
| bounded   | 0 or 1 | 0       |

When set to 1, then it turns the 'viewbox' parameter (see above) into
a filter paramter, excluding any results outside the viewbox.

When `bounded=1` is given and the viewbox is small enough, then an amenity-only
search is allowed. Give the special keyword for the amenity in square
brackets, e.g. `[pub]` and a selection of objects of this type is returned.
There is no guarantee that the result returns all objects in the area.


### Polygon output

| Parameter | Value  | Default |
|-----------| -----  | ------- |
| polygon_geojson | 0 or 1 | 0 |
| polygon_kml     | 0 or 1 | 0 |
| polygon_svg     | 0 or 1 | 0 |
| polygon_text    | 0 or 1 | 0 |

Add the full geometry of the place to the result output. Output formats
in GeoJSON, KML, SVG or WKT are supported. Only one of these
options can be used at a time.

| Parameter | Value  | Default |
|-----------| -----  | ------- |
| polygon_threshold | floating-point number | 0.0 |

When one of the polygon_* outputs is chosen, return a simplified version
of the output geometry. The parameter describes the
tolerance in degrees with which the geometry may differ from the original
geometry. Topology is preserved in the geometry.

### Other

| Parameter | Value  | Default |
|-----------| -----  | ------- |
| email     | valid email address | _unset_ |

If you are making large numbers of request please include an appropriate email
address to identify your requests. See Nominatim's
[Usage Policy](https://operations.osmfoundation.org/policies/nominatim/) for more details.

| Parameter | Value  | Default |
|-----------| -----  | ------- |
| dedupe    | 0 or 1 | 1       |

Sometimes you have several objects in OSM identifying the same place or
object in reality. The simplest case is a street being split into many
different OSM ways due to different characteristics. Nominatim will
attempt to detect such duplicates and only return one match. Setting
this parameter to 0 disables this deduplication mechanism and
ensures that all results are returned.

| Parameter | Value  | Default |
|-----------| -----  | ------- |
| debug     | 0 or 1 | 0       |

Output assorted developer debug information. Data on internals of Nominatim's
"search loop" logic, and SQL queries. The output is HTML format.
This overrides the specified machine readable format.


## Examples


##### XML with KML polygon

* [https://nominatim.openstreetmap.org/search?q=135+pilkington+avenue,+birmingham&format=xml&polygon_kml=1&addressdetails=1](https://nominatim.openstreetmap.org/search?q=135+pilkington+avenue,+birmingham&format=xml&polygon_kml=1&addressdetails=1)

```xml
<?xml version="1.0" encoding="UTF-8" ?>
<searchresults timestamp="Tue, 08 Aug 2023 15:45:41 +00:00"
               attribution="Data © OpenStreetMap contributors, ODbL 1.0. http://osm.org/copyright"
               querystring="135 pilkington avenue, birmingham"
               more_url="https://nominatim.openstreetmap.org/search?q=135+pilkington+avenue%2C+birmingham&amp;polygon_kml=1&amp;addressdetails=1&amp;limit=20&amp;exclude_place_ids=125279639&amp;format=xml"
               exclude_place_ids="125279639">
  <place place_id="125279639"
         osm_type="way"
         osm_id="90394480"
         lat="52.5487921"
         lon="-1.8164308"
         boundingbox="52.5487473,52.5488481,-1.8165130,-1.8163464"
         place_rank="30"
         address_rank="30"
         display_name="135, Pilkington Avenue, Maney, Sutton Coldfield, Wylde Green, Birmingham, West Midlands Combined Authority, England, B72 1LH, United Kingdom"
         class="building"
         type="residential"
         importance="9.999999994736442e-08">
    <geokml>
      <Polygon>
        <outerBoundaryIs>
          <LinearRing>
            <coordinates>-1.816513,52.5487566 -1.816434,52.5487473 -1.816429,52.5487629 -1.8163717,52.5487561 -1.8163464,52.5488346 -1.8164599,52.5488481 -1.8164685,52.5488213 -1.8164913,52.548824 -1.816513,52.5487566</coordinates>
          </LinearRing>
        </outerBoundaryIs>
      </Polygon>
    </geokml>
    <house_number>135</house_number>
    <road>Pilkington Avenue</road>
    <hamlet>Maney</hamlet>
    <town>Sutton Coldfield</town>
    <village>Wylde Green</village>
    <city>Birmingham</city>
    <ISO3166-2-lvl8>GB-BIR</ISO3166-2-lvl8>
    <state_district>West Midlands Combined Authority</state_district>
    <state>England</state>
    <ISO3166-2-lvl4>GB-ENG</ISO3166-2-lvl4>
    <postcode>B72 1LH</postcode>
    <country>United Kingdom</country>
    <country_code>gb</country_code>
  </place>
</searchresults>
```

##### JSON with SVG polygon

[https://nominatim.openstreetmap.org/search?q=Unter%20den%20Linden%201%20Berlin&format=json&addressdetails=1&limit=1&polygon_svg=1](https://nominatim.openstreetmap.org/search?q=Unter%20den%20Linden%201%20Berlin&format=json&addressdetails=1&limit=1&polygon_svg=1)

```json
[
  {
    "address": {
      "ISO3166-2-lvl4": "DE-BE",
      "borough": "Mitte",
      "city": "Berlin",
      "country": "Deutschland",
      "country_code": "de",
      "historic": "Kommandantenhaus",
      "house_number": "1",
      "neighbourhood": "Friedrichswerder",
      "postcode": "10117",
      "road": "Unter den Linden",
      "suburb": "Mitte"
    },
    "boundingbox": [
      "52.5170798",
      "52.5173311",
      "13.3975116",
      "13.3981577"
    ],
    "class": "historic",
    "display_name": "Kommandantenhaus, 1, Unter den Linden, Friedrichswerder, Mitte, Berlin, 10117, Deutschland",
    "importance": 0.8135042058306902,
    "lat": "52.51720765",
    "licence": "Data © OpenStreetMap contributors, ODbL 1.0. https://osm.org/copyright",
    "lon": "13.397834399325466",
    "osm_id": 15976890,
    "osm_type": "way",
    "place_id": 108681845,
    "svg": "M 13.3975116 -52.5172905 L 13.397549 -52.5170798 13.397715 -52.5170906 13.3977122 -52.5171064 13.3977392 -52.5171086 13.3977417 -52.5170924 13.3979655 -52.5171069 13.3979623 -52.5171233 13.3979893 -52.5171248 13.3979922 -52.5171093 13.3981577 -52.5171203 13.398121 -52.5173311 13.3978115 -52.5173103 Z",
    "type": "house"
  }
]
```

##### JSON with address details

[https://nominatim.openstreetmap.org/search?addressdetails=1&q=bakery+in+berlin+wedding&format=jsonv2&limit=1](https://nominatim.openstreetmap.org/search?addressdetails=1&q=bakery+in+berlin+wedding&format=jsonv2&limit=1)

```json
[
  {
    "address": {
      "ISO3166-2-lvl4": "DE-BE",
      "borough": "Mitte",
      "city": "Berlin",
      "country": "Deutschland",
      "country_code": "de",
      "neighbourhood": "Sprengelkiez",
      "postcode": "13347",
      "road": "Lindower Straße",
      "shop": "Ditsch",
      "suburb": "Wedding"
    },
    "addresstype": "shop",
    "boundingbox": [
      "52.5427201",
      "52.5427654",
      "13.3668619",
      "13.3669442"
    ],
    "category": "shop",
    "display_name": "Ditsch, Lindower Straße, Sprengelkiez, Wedding, Mitte, Berlin, 13347, Deutschland",
    "importance": 9.99999999995449e-06,
    "lat": "52.54274275",
    "licence": "Data © OpenStreetMap contributors, ODbL 1.0. http://osm.org/copyright",
    "lon": "13.36690305710228",
    "name": "Ditsch",
    "osm_id": 437595031,
    "osm_type": "way",
    "place_id": 204751033,
    "place_rank": 30,
    "type": "bakery"
  }
]
```

##### GeoJSON

[https://nominatim.openstreetmap.org/search?q=17+Strada+Pictor+Alexandru+Romano%2C+Bukarest&format=geojson](https://nominatim.openstreetmap.org/search?q=17+Strada+Pictor+Alexandru+Romano%2C+Bukarest&format=geojson)

```json
{
  "type": "FeatureCollection",
  "licence": "Data © OpenStreetMap contributors, ODbL 1.0. https://osm.org/copyright",
  "features": [
    {
      "type": "Feature",
      "properties": {
        "place_id": "35811445",
        "osm_type": "node",
        "osm_id": "2846295644",
        "display_name": "17, Strada Pictor Alexandru Romano, Bukarest, Bucharest, Sector 2, Bucharest, 023964, Romania",
        "place_rank": "30",
        "category": "place",
        "type": "house",
        "importance": 0.62025
      },
      "bbox": [
        26.1156689,
        44.4354754,
        26.1157689,
        44.4355754
      ],
      "geometry": {
        "type": "Point",
        "coordinates": [
          26.1157189,
          44.4355254
        ]
      }
    }
  ]
}
```

##### GeocodeJSON

[https://nominatim.openstreetmap.org/search?q=%CE%91%CE%B3%CE%AF%CE%B1+%CE%A4%CF%81%CE%B9%CE%AC%CE%B4%CE%B1%2C+%CE%91%CE%B4%CF%89%CE%BD%CE%B9%CE%B4%CE%BF%CF%82%2C+Athens%2C+Greece&format=geocodejson](https://nominatim.openstreetmap.org/search?q=%CE%91%CE%B3%CE%AF%CE%B1+%CE%A4%CF%81%CE%B9%CE%AC%CE%B4%CE%B1%2C+%CE%91%CE%B4%CF%89%CE%BD%CE%B9%CE%B4%CE%BF%CF%82%2C+Athens%2C+Greece&format=geocodejson)

```json
{
  "type": "FeatureCollection",
  "geocoding": {
    "version": "0.1.0",
    "attribution": "Data © OpenStreetMap contributors, ODbL 1.0. https://osm.org/copyright",
    "licence": "ODbL",
    "query": "Αγία Τριάδα, Αδωνιδος, Athens, Greece"
  },
  "features": [
    {
      "type": "Feature",
      "properties": {
        "geocoding": {
          "type": "place_of_worship",
          "label": "Αγία Τριάδα, Αδωνιδος, Άγιος Νικόλαος, 5º Δημοτικό Διαμέρισμα Αθηνών, Athens, Municipality of Athens, Regional Unit of Central Athens, Region of Attica, Attica, 11472, Greece",
          "name": "Αγία Τριάδα",
          "admin": null
        }
      },
      "geometry": {
        "type": "Point",
        "coordinates": [
          23.72949633941,
          38.0051697
        ]
      }
    }
  ]
}
```