Windshaft-cartodb/docs/Template-maps.md
2014-03-04 15:39:21 +01:00

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Template maps are layergroup configurations that rather than being
fully defined contain variables that can be set to produce a different
layergroup configurations (instantiation).
Template maps are persistent, can only be created and deleted by the
CartoDB user showing a valid API_KEY.
Instantiating a signed template map would result in a [signed
map](https://github.com/CartoDB/Windshaft-cartodb/wiki/Signed-maps)
instance that would be signed with the same signature as the template.
Deleting a signed template results in deletion of all signatures created
as a result of instantiation.
# Template format
A templated layergroup would allow using placeholders
in the "cartocss" and "sql" elements in the "option"
field of any "layer" of a layergroup configuration
(see https://github.com/CartoDB/Windshaft/wiki/MapConfig-specification).
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: ``<%= my_color %>``.
The set of supported placeholders for a template will need to be
explicitly defined specifying type and default value for each.
**placeholder types**
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)
* ... (add more as need arises)
Placeholder default value will be used when not provided at
instantiation time and could be used to test validity of the
template by creating a default instance.
Additionally you'll be able to embed an authorization
certificate that would be used to sign any instance of the template.
```js
// template.json
{
version: '0.0.1',
// 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
name: 'template_name',
// embedded authorization certificate
auth: {
// See https://github.com/CartoDB/Windshaft-cartodb/wiki/Signed-maps
method: 'token', // or "open" (the default if no "method" is given)
valid_tokens: ['auth_token1','auth_token2'] // only (required and non empty) for 'token' method
},
// 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
placeholders: {
color: {
type:'css_color',
default:'red'
},
cartodb_id: {
type:'number',
default: 1
}
},
layergroup: {
// see https://github.com/CartoDB/Windshaft/wiki/MapConfig-specification
"version": "1.0.1",
"layers": [{
"type": "cartodb",
"options": {
"cartocss_version": "2.1.1",
"cartocss": "#layer { polygon-fill: <%= color %>; }",
"sql": "select * from european_countries_e WHERE cartodb_id = <%= cartodb_id %>"
}
}]
}
}
```
# Creating a templated map
You can create a signed template map with a single call (for simplicity).
You'd use a POST sending JSON data:
```sh
curl -X POST \
-H 'Content-Type: application/json' \
-d @template.json \
'https://docs.cartodb.com/tiles/template?api_key=APIKEY'
```
The response would be like this:
```js
{
"template_id":"@template_name"
}
```
If a template with the same name exists in the user storage,
a 400 response is generated.
Errors are in this form:
```js
{
"error":"Some error string here"
}
```
# Updating an existing template
Update of a template map implies removal all signatures from previous
map instances.
You can update a signed template map with a PUT:
```sh
curl -X PUT \
-H 'Content-Type: application/json' \
-d @template.json \
'https://docs.cartodb.com/tiles/template/:template_name?api_key=APIKEY'
```
A template with the same name will be updated, if any.
The response would be like this:
```js
{
"template_id":"@template_name"
}
```
If a template with the same name does NOT exist,
a 400 HTTP response is generated with an error in this format:
```js
{
"error":"Some error string here"
}
```
# Listing available templates
You can get a list of available templates with a GET to ``/template``.
A valid api_key is required.
```sh
curl -X GET 'https://docs.cartodb.com/tiles/template?api_key=APIKEY'
```
The response would be like this:
```js
{
"template_ids": ["@template_name1","@template_name2"]
}
```
Or, on error:
```js
{
"error":"Some error string here"
}
```
# Getting a specific template
You can get the definition of a template with a
GET to ``/template/:template_name``.
A valid api_key is required.
Example:
```sh
curl -X GET 'https://docs.cartodb.com/tiles/template/@template_name?auth_token=AUTH_TOKEN'
```
The response would be like this:
```js
{
"template": {...} // see template.json above
}
```
Or, on error:
```js
{
"error":"Some error string here"
}
```
# Instantiating a template map
You can instantiate a template map passing all required parameters with
a POST to ``/template/:template_name``.
Valid credentials will be needed, if required by the template.
```js
// params.js
{
color: '#ff0000',
cartodb_id: 3
}
```
```sh
curl -X POST \
-H 'Content-Type: application/json' \
-d @params.js \
'https://docs.cartodb.com/tiles/template/@template_name?auth_token=AUTH_TOKEN'
```
The response would be like this:
```js
{
"layergroupid":"docs@fd2861af@c01a54877c62831bb51720263f91fb33:123456788",
"last_updated":"2013-11-14T11:20:15.000Z"
}
```
or, on error:
```js
{
"error":"Some error string here"
}
```
You can then use the ``layergroupid`` for fetching tiles and grids as you do
normally ( see https://github.com/CartoDB/Windshaft/wiki/Multilayer-API).
But you'll still have to show the ``auth_token``, if required by the template
(see https://github.com/CartoDB/Windshaft-cartodb/wiki/Signed-maps)
Instances of a signed template map will be signed with the same signature
certificate associated with the template. Such certificate would contain
a reference to the template identifier, so that it can be revoked every
time the template is updated or deleted.
### using JSONP
There is also a special endpoint to be able to instanciate using JSONP (for old browsers)
```
curl 'https://docs.cartodb.com/tiles/template/@template_name/jsonp?auth_token=AUTH_TOKEN&callback=function_name&config=template_params_json'
```
it takes the ``callback`` function (required), ``auth_token`` in case the template needs auth and ``config`` which is the variabñes for the template (in case it has variables). For example config may be created (using javascript)
```
url += "config=" + encodeURIComponent(
JSON.stringify({ color: 'red' });
```
the response it's in this format:
```
jQuery17205720721024554223_1390996319118(
{
layergroupid: "dev@744bd0ed9b047f953fae673d56a47b4d:1390844463021.1401",
last_updated: "2014-01-27T17:41:03.021Z"
}
)
```
# Deleting a template map
Deletion of a template map will imply removal all instance signatures
You can delete a templated map with a DELETE to ``/template/:template_name``:
```sh
curl -X DELETE 'https://docs.cartodb.com/tiles/template/@template_name?auth_token=AUTH_TOKEN'
```
On success, a 204 (No Content) response would be issued.
Otherwise a 4xx response with this format:
```js
{
"error":"Some error string here"
}
```