Consuming Datachain REST API

Get the list of Exposures available to the logged-in user

Datachain Marketplace provides a REST API that allows you to obtain the metadata of Exposures (information identical to that presented in the MarketPlace interface). This API is accessible at the URL:
https://VOTRE_URL_MARKETPLACE/dmp-api/expositions
and returns, in the form of a JSON array, the following information about the Exposures.

[
  {
    "id": 1001,
    "label": "My exposition projet",
    "rootCode": "MyProjectRootCode",
    "expositions": [
      {
        "title": "Exposition API - Datablock_exposition",
        "details": "Detail",
        "keywords": [
          "Mot Clé"
        ],
        "id": 1002,
        "updateDate": 1760437413237,
        "accessPoint": "exposition1",
        "dcRestUrl": "http://VOTRE_URL_MARKETPLACE/dmp-api/data/MyProjectRootCode/exposition",
        "odataUrl": "http://VOTRE_URL_MARKETPLACE/dmp-api/odata/MyProjectRootCode/exposition?$format=json",
        "columns": [
          {
            "alias": "bool",
            "idColumn": false,
            "list": false,
            "filter": true,
            "type": "BOOLEAN"
          },
          {
            "alias": "list_string",
            "idColumn": false,
            "list": true,
            "filter": true,
            "type": "STRING"
          },
          // Others Colonnes
        ]
      },
      // Others Expositions
    ]
  },
  // Others Projects
]

API - 1. Information
Key	Description
rootCode	Grouping code for Exposures (project root)
id	Unique identifier (not needed)
expositions	Array of Exposures associated with the root
expositions[].accessPoint	Name of the Exposure, used in the URL
expositions[].id	Unique identifier (not needed)
expositions[].dcRestUrl	REST API URL
expositions[].odataUrl	OData API URL
expositions[].title	Name of the Exposure in metadata
expositions[].details	Description of the Exposure in metadata
expositions[].keywords	Keywords associated in the metadata
expositions[].columns	Array of columns
expositions[].columns[].alias	Column alias
expositions[].columns[].description	Column description
expositions[].columns[].list	Indicates whether the column is of list type
expositions[].columns[].type	Datachain type (among: STRING, INTEGER, BIG_INTEGER, DECIMAL, BOOLEAN, LONG, DATE)
expositions[].columns[].filter	Boolean indicating whether filters can be applied

Get the data of an Exposure

This API allows you to obtain the data of an Exposure in the form of a list of records, with pagination.

Example of a request to the Exposure API

https://VOTRE_URL_MARKETPLACE/dmp-api/data/racine/exposition?select=id,nom&filter=nom=beginsWith=A

Query syntaxes and operators

You must follow the DataChain REST API syntax to build queries and call the APIs.

API - 2. Query syntaxes
Syntax	Description	Required?
http://VOTRE_URL_MARKETPLACE/dmp-api/data/<racine>/<exposition>?hitsPerPage=100&page=1	Base access URL
exposition?	Name of the access point assigned when configuring the API
select=	Selects the columns to return in the response. If this section is not specified, all exposed columns are returned.
filter=	Filters based on the defined filter parameters Example: filter=nom=beginsWith=A The filter syntax is shown in the following table.
page=	Indicates the page returned. By default, page 1 is used Example: page=5
hitsPerPage=	Indicates the number of rows per page Example: hitsPerPage=50
sort=	Sort based on defined parameters Example: sort=nom:desc
&	Character to add between each query syntax element Example: sort=ipp:asc,nom:desc&hitsPerPage=50

API - 3. Convention / Operators
Operator	Syntax	Accepted types	Example
And	and	Other operators	(nom=='DURAND') and* (prenom=='Pierre')*
Or	or	Other operators	(nom=='DURAND') or (nom=='DUPONT')
Equal	==	String, Numeric, Boolean, Date	nom=='mon ami' ou nom==ami
Not equal	!=	String, Numeric, Boolean, Date	nom!='mon ami' ou nom!=ami
Greater than	> or =gt=	Numeric, Date	> 10 ou =gt=10
Greater than or equal	>= or =ge=	Numeric, Date	>= 10 ou =ge=10
Less than	< or =lt=	Numeric, Date	< 10 ou =lt=10
Less than or equal	≤ or =le=	Numeric, Date	≤ 10 ou =le=10
In list	=in=	String, Numeric, Boolean, Date	=in=(ami,copain)
Not in list	=out= or =notIn=	String, Numeric, Boolean, Date	=out=(ami,copain) ou =notIn=('mon ami','mon copain')
Between	=between=	Numeric, Date	=between=(2,5) ou =between=('','')
Not between	=notBetween=	Numeric, Date	=notBetween=(2,5) ou =notBetween=('','')
Contains	=contains=	string	=contains=('grenoble')
Does not contain	=notContains=	string	=notContains=(grenoble')
Begins with	=beginsWith=	string	=beginsWith=A ou =beginsWith='A B'
Does not begin with	=notBeginsWith=	string	=NotBeginsWith=A ou =NotBeginsWith='A B'
Ends with	=endsWith=	string	=endsWith=A ou =endsWith='A B'
Does not end with	=notEndsWith=	string	=notEndsWith=A ou =notEndsWith='A B'
Is null / Is not null	=isNull=	String, Numeric, Boolean, Date	Nom=isNull=true ou Nom=isNull=false

Pagination

For paginated requests, it is necessary to know whether all the data has been received.

The Datachain REST API offers two solutions for this:

The counting API: This API can be called before the pagination calls, then used in a processing loop (by performing some calculations)

int count=callCountApi();
// Paginate éléments by 1000
int hitsPerPages=1000;
int page=0;
while (hitsPerPages * page < count)
{
page++; // first APi rest Page is 1
callAndStoreDataApi(page, hitsPerPages);
}

dc_has_next header: during a data request, the API systematically returns an HTTP header 'dc_has_next', set to true if there is more data, and false otherwise. This header can be used to loop based on its value.

boolean continueIteration=true;
// Paginate éléments by 1000
int hitsPerPages=1000;
int page=0;
while (continueIteration)
{
page++; // first APi rest Page is 1
continueIteration = callAndStoreDataApiAndReturnDcHasNextHeaderValue(page, hitsPerPages);
}

Note: The API also returns an HTTP header "dc_count", which returns the number of available items matching the request (the value is therefore identical to the Count API call.)

Get a single item from an Exposure

When an Exposure exposes data with a unique identifier (indicated in the Exposure profile, 'Id' column of 'Available columns'), it is possible to retrieve an item with id 'ITEM_ID' by calling the URL: https://VOTRE_URL_MARKETPLACE/dmp-api/data/racine/exposition/items/ITEM_ID

Mapping of Datachain types to JSON types.

API - 4. Mapping of Datachain types to JSON types
Datachain Type	OData Type
Booléen / Boolean	boolean
Décimal / Decimal	Number
Entier / Integer	Number
Grand nombre entier / Big Integer	Number
Chaîne de caractère / String	String
Date / Date	Date in ISO 8601 format as a String (e.g., "2025-10-15T07:34:13Z")
Liste(Type) / List(Type)	Array[Type]