19 KiB
Maps API
The CartoDB Maps API allows you to generate maps based on data hosted in your CartoDB account and style them using CartoCSS. The API generates a XYZ based URL to fetch Web Mercator projected tiles using web clients like Leaflet, Google Maps, OpenLayers.
You can create two types of maps with the Maps API:
-
Anonymous maps
Maps that can be created using your CartoDB public data. Any client can change the read-only SQL and CartoCSS parameters that generate the map tiles. These maps can be created from a JavaScript application alone and no authenticated calls are needed. See [this CartoDB.js example]({{ '/cartodb-platform/cartodb-js.html' | prepend: site.baseurl }}). -
Named maps
Maps that access to your private data. These maps require an owner to setup and modify any SQL and CartoCSS parameters and are not modifiable without new setup calls.
Quickstart
Anonymous maps
Here is an example of how to create an anonymous map with JavaScript:
{% highlight javascript %} var mapconfig = { "version": "1.0.1", "layers": [{ "type": "cartodb", "options": { "cartocss_version": "2.1.1", "cartocss": "#layer { polygon-fill: #FFF; }", "sql": "select * from european_countries_e" } }] }
$.ajax({ crossOrigin: true, type: 'POST', dataType: 'json', contentType: 'application/json', url: 'http://documentation.cartodb.com/api/v1/map', data: JSON.stringify(mapconfig), success: function(data) { var templateUrl = 'http://documentation.cartodb.com/api/v1/map/' + data.layergroupid + '{z}/{x}/{y}.png' console.log(templateUrl); } }) {% endhighlight %}
Named maps
Let's create a named map using some private tables in a CartoDB account. The following API call creates a map of European countries that have a white fill color:
{% highlight javascript %} // mapconfig.json { "version": "0.0.1", "name": "test", "auth": { "method": "open" }, "layergroup": { "layers": [{ "type": "cartodb", "options": { "cartocss_version": "2.1.1", "cartocss": "#layer { polygon-fill: #FFF; }", "sql": "select * from european_countries_e" } }] } } {% endhighlight %}
The map config needs to be sent to CartoDB's Map API using an authenticated call. Here we use a command line tool called curl. For more info about this tool see this blog post or type man curl in bash. Using curl the call would look like:
To get the URL to fetch the tiles you need to instantiate the map.
The response will return JSON with properties for the layergroupid and the timestamp (last_updated) of the last data modification.
Here is an example response:
{% highlight javascript %} { "layergroupid": "c01a54877c62831bb51720263f91fb33:0", "last_updated": "1970-01-01T00:00:00.000Z" } {% endhighlight %}
You can use the layergroupid to instantiate a URL template for accessing tiles on the client. Here we use the layergroupid from the example response above in this URL template:
{% highlight bash %} http://documentation.cartodb.com/tiles/layergroup/c01a54877c62831bb51720263f91fb33:0/{z}/{x}/{y}.png {% endhighlight %}
General Concepts
The following concepts are the same for every endpoint in the API except when it's noted explicitly.
Auth
By default, users do not have access to private tables in CartoDB. In order to instantiate a map from private table data an API Key is required. Additionally, to include some endpoints an API Key must be included (e.g. creating a named map).
To execute an authorized request, api_key=YOURAPIKEY should be added to the request URL. The param can be also passed as POST param. We strongly advise using HTTPS when you are performing requests that include your api_key.
Errors
Errors are reported using standard HTTP codes and extended information encoded in JSON with this format:
{% highlight javascript %} { "errors": [ "access forbidden to table TABLE" ] } {% endhighlight %}
If you use JSONP, the 200 HTTP code is always returned so the JavaScript client can receive errors from the JSON object.
CORS support
All the endpoints which might be accessed using a web browser add CORS headers and allow OPTIONS method.
Anonymous Maps
Anonymous maps allows you to instantiate a map given SQL and CartoCSS. It also allows you to add interaction capabilities using UTF Grid.
Instantiate
Definition
{% highlight html %} POST /api/v1/map {% endhighlight %}Params
{% highlight javascript %} { "version": "1.0.1", "layers": [{ "type": "cartodb", "options": { "cartocss_version": "2.1.1", "cartocss": "#layer { polygon-fill: #FFF; }", "sql": "select * from european_countries_e", "interactivity": ["cartodb_id", "iso3"] } }] } {% endhighlight %}
Should be a Mapconfig.
Response
The response includes:
-
layergroupid
The ID for that map, used to compose the URL for the tiles. The final URL is:{% highlight html %} http://{account}.cartodb.com/api/v1/map/:layergroupid/{z}/{x}/{y}.png {% endhighlight %}
-
updated_at
The ISO date of the last time the data involved in the query was updated. -
metadata (optional)
Includes information about the layers. Some layers may not have metadata. -
cdn_url
URLs to fetch the data using the best CDN for your zone.
Example
The tiles can be accessed using:
{% highlight bash %} http://documentation.cartodb.com/api/v1/map/c01a54877c62831bb51720263f91fb33:0/{z}/{x}/{y}.png {% endhighlight %}
For UTF grid tiles:
{% highlight bash %} http://documentation.cartodb.com/api/v1/map/c01a54877c62831bb51720263f91fb33:0/:layer/{z}/{x}/{y}.grid.json {% endhighlight %}
For attributes defined in attributes section:
{% highlight bash %} http://documentation.cartodb.com/api/v1/map/c01a54877c62831bb51720263f91fb33:0/:layer/attributes/:feature_id {% endhighlight %}
Which returns JSON with the attributes defined, like:
{% highlight javascript %} { c: 1, d: 2 } {% endhighlight %}
Notice UTF Grid and attributes endpoints need an intenger parameter, layer. That number is the 0-based index of the layer inside the mapconfig. So in this case 0 returns the UTF grid tiles/attributes for layer 0, the only layer in the example mapconfig. If a second layer was available it could be returned with 1, a third layer with 2, etc.
Create JSONP
The JSONP endpoint is provided in order to allow web browsers access which don't support CORS.
Definition
{% highlight bash %} GET /api/v1/map?callback=method {% endhighlight %}Params
-
auth_token (optional)
If the named map needs authorization. -
config
Encoded JSON with the params for creating named maps (the variables defined in the template). -
lmza
This attribute contains the same as config but LZMA compressed. It cannot be used at the same time asconfig. -
callback
JSON callback name.
Example
Remove
Anonymous maps cannot be removed by an API call. They will expire after about five minutes but sometimes longer. If an anonymous map expires and tiles are requested from it, an error will be raised. This could happen if a user leaves a map open and after time returns to the map an attempts to interact with it in a way that requires new tiles (e.g. zoom). The client will need to go through the steps of creating the map again to fix the problem.
Named Maps
Named maps are essentially the same as anonymous maps but the mapconfig is stored in the server and given a unique name. Two other big differences are that you can created named maps from private data and that users without an API Key can see them even though they are from that private data.
The main two differences compared to anonymous maps are:
-
auth layer
This allows you to control who is able to see the map based on a token auth -
templates
Since the mapconfig is static it can contain some variables so the client con modify the map appearance using those variables.
Template maps are persistent with no preset expiration. They can only be created or deleted by a CartoDB user with a valid API_KEY (see auth section).
Create
Definition
{% highlight html %} POST /api/v1/map/named {% endhighlight %}Params
Arguments
- name: there can be at most 1 template with the same name for any user valid names start with a letter and only contains letter, numbers or underscores
- auth:
- method
"token"or"open"(the default if no"method"is given)
- method
- placeholders: Variables not listed here are not substituted. Variable not provided at instantiation time trigger an error. A default is required for optional variables. Type specification is used for quoting, to avoid injections see template format section below.
- layergroup: the layer list definition. This is the MapConfig explained in anonymous maps see https://github.com/CartoDB/Windshaft/blob/master/doc/MapConfig-1.1.0.md
Template Format
A templated layergroup allows using placeholders in the "cartocss" and "sql" elements of the "option" object in any "layer" of a layergroup configuration
Valid placeholder names start with a letter and can only contain letters, numbers or underscores. They have to be written between <%= and %> strings in order to be replaced.
Example
{% highlight javascript %} <%= my_color %> {% endhighlight %}
The set of supported placeholders for a template will need to be explicitly defined with a specific type and default value for each.
Placeholder Types
The placeholder type will determine the kind of escaping for the associated value. Supported types are:
- sql_literal internal single-quotes will be sql-escaped
- sql_ident internal double-quotes will be sql-escaped
- number can only contain numerical representation
- css_color can only contain color names or hex-values
Placeholder default values will be used whenever new values are not provided as options at the time of creation on the client. They can also be used to test the template by creating a default version with now options provided.
When using templates, be very careful about your selections as they can give broad access to your data if they are defined losely.
Instantiate
Instantiating a map allows you to get the information needed to fetch tiles. That temporal map is an anonymous map.
Definition
{% highlight html %} POST /api/v1/map/named/:template_name {% endhighlight %}Param
{% highlight javascript %} // params.json { color: "#ff0000", cartodb_id: 3 } {% endhighlight %}
The fields you pass as params.json depend on the variables allowed by the named map. If there are variables missing it will raise an error (HTTP 400)
- auth_token optional if the named map needs auth
Example
You can initialize a template map by passing all of the required parameters in a POST to /api/v1/map/named/:template_name.
Valid credentials will be needed if required by the template.
You can then use the layergroupid for fetching tiles and grids as you would normally (see anonymous map section). However, you'll need to show the auth_token, if required by the template.
Using JSONP
There is also a special endpoint to be able to initialize a map using JSONP (for old browsers).
Definition
{% highlight bash %} GET /api/v1/map/named/:template_name/jsonp {% endhighlight %}Params
- auth_token (optional) If the named map needs auth
- config Encoded JSON with the params for creating named maps (the variables defined in the template)
- lmza This attribute contains the same as config but LZMA compressed. It cannot be used at the same time than
config. - callback: JSON callback name
This takes the callback function (required), auth_token if the template needs auth, and config which is the variable for the template (in cases where it has variables).
{% highlight javascript %} url += "config=" + encodeURIComponent( JSON.stringify({ color: 'red' }); {% endhighlight %}
The response is in this format:
{% highlight javascript %} jQuery17205720721024554223_1390996319118({ layergroupid: "dev@744bd0ed9b047f953fae673d56a47b4d:1390844463021.1401", last_updated: "2014-01-27T17:41:03.021Z" }) {% endhighlight %}
Update
Definition
{% highlight bash %} PUT /api/v1/map/:map_name {% endhighlight %}Params
Same params used to create a map.
Response
Same as updating a map.
Other Info
Updating a named map removes all the named map instances so they need to be initialized again.
Example
If any template has the same name, it will be updated.
If a template with the same name does NOT exist, a 400 HTTP response is generated with an error in this format:
{% highlight javascript %} { "error": "error string here" } {% endhighlight %}
Updating a template map will also remove all signatures from previously initialized maps.
Delete
Delete the specified template map from the server and disables any previously initialized versions of the map.
Definition
{% highlight bash %} DELETE /template/:template_name {% endhighlight %}Example
On success, a 204 (No Content) response would be issued. Otherwise a 4xx response with with an error will be returned:
Listing Available Templates
This allows you to get a list of all available templates.
Definition
{% highlight bash %} GET /api/v1/map/named/ {% endhighlight %}Params
- api_key is required
Example
Getting a Specific Template
This gets the definition of a template
Definition
{% highlight bash %} GET /api/v1/map/named/:template_name {% endhighlight %}Params
- api_key is required