Reading Data from OData Services

With OData services you not only can access OData actions, but also read and use the data of entity sets exposed via OData services.

This lets you use the data of the entity sets for any purpose except data visualization in a table or a chart. For example, you can read and display one member in a text widget. To access entity sets exposed via OData Services, you can use two APIs in your script:

  • getEntity: for retrieving a single OData entity from an entity set, by specifying the key to the entity. This is similar to selecting a single row from a SQL table via SELECT * FROM T1 WHERE ID = <id>.

  • getEntitiesFromEntitySet: for retrieving all entities from an OData entity set. This is similar to SELECT TOP <N> * FROM T1. With this API you can use the OData system query options filter, orderby, select, count, top and skip.
    Note

    The number of entities is limited to 1000 if no system query options have been used. If system query options are set, the number of retrieved entities is not limited, unless you set a value for the system query option top. top.

  • getEntitiesCountFromEntitySet: for retrieving the number of entities from an OData entity set. This API works like the getEntitiesFromEntitySet API and you can also use the OData system query options filter, orderby, select, count, top and skip.

Example
The parameters filter, orderby, and select have string values which will be 1:1 used in the OData request. This allows you to use all features supported by the query options. The parameters skip and top have integer values, that will be used in the OData request. The second parameter in both API methods is passed as object, in which the system query options can be combined in an arbitrary way.
Sample Code
// returns a list of entities, filtered by the given system query option(s)
ODataService_1.getEntitiesFromEntitySet("Departments", {filter: "contains(Sector,'Consulting')", orderby: "Sector asc" });
// returns a list of entities, not filtered
ODataService_1.getEntitiesFromEntitySet("Equipments");
// returns the number of entities in the entity set "TEAMS"
ODataService_2.getEntitiesCountFromEntitySet("TEAMS");
// returns the number of entities in the entity set "EMPLOYEES", filtered by the given system query option(s)
ODataService_2.getEntitiesCountFromEntitySet("EMPLOYEES", {skip: 5, top: 10});
Note
When you want to read data from OData services, note the following feature limitations:

  • chaining from one entity set to another is not supported

  • expand (analogous to joining) is not supported

  • entity sets with parameters are not supported

  • entity sets with mandatory filters are not supported