Supported OData Operations

1 Introduction

This is a list of supported operations for OData services.

A published OData service is automatically documented. Studio Pro allows you to export the OpenAPI specification, which is a machine-readable file that is supported by most API tools, like Swagger UI and Postman.

When running your app, you can use Swagger UI to read this documentation and test your service.

Below is a more descriptive explanation of the operations that a published OData service supports.

2 Retrieving Objects

2.1 Retrieving All Objects

To retrieve all objects, specify the URI (for example, /odata/myservice/v1/Employees). You can see this if you specify the URI in a browser.

2.2 Retrieving a Single Object

To retrieve a single object, pass the object identifier in the URI (for example, /odata/myservice/v1/Employees(8444249301330581)).

2.3 Query Options

2.3.1 Retrieving Associated Objects

To retrieve associated objects, pass the $expand query parameter.

For example, imagine you have four entities in your domain model: Employee, Car, Address, and City. They include the following associations:

• An association between Employee and Car
• An association between Employee and Address
• An association between City and Address

In this case, you could retrieve associated objects by passing /odata/myservice/v1/Employees?$expand=Cars,Address($expand=City) in OData v4 or /odata/myservice/v1/Employees?$expand=Cars,Address/City in OData v3 (⚠ deprecated).

2.3.2 Counting the Number of Objects

2.3.2.1 Retrieving a Count of Objects

To find out how many objects there are, pass the $count query option (for example, /odata/myservice/v1/Employees/$count). This returns an integer representing the number of objects.

2.3.2.2 (Inline) Count

You can also adjust your query so that the result includes a count of the number of items returned. To do this in OData v4, set the $count query option to true (like this: ?$count=true). To do this in OData v3 (⚠ deprecated), set the $inlinecount query option to allpages (like this: ?$inlinecount=allpages).

2.3.3 Filtering

To apply a filter, append a $filter=... parameter to the request, like this: /Employees?$filter=Name eq 'John'.

2.3.3.1 Passing attributes

This table describes how to pass values for different attribute types:

2.3.3.2 Comparison Operators

Mendix supports the following comparison operators:

2.3.3.3 Functions

¹ In OData v3 (⚠ deprecated), the contains function is called substringof, and its arguments are reversed. Here is an example: /Employees?$filter=substringof('f', Name).

2.3.3.4 Combining Filters

Filters can be combined with and, or, not, and () (for example, ?$filter=Name eq 'John' and (Age gt 65 or Age lt 11)).

2.3.3.5 Filtering by Association

You can filter on the attributes of an associated entity. The syntax depends on whether the association exposes one object or a list of objects:

Filtering on an associated object or list in this way is possible only when you expose associations as a link. It is not possible when you expose associations as an associated object ID.

2.3.3.6 Arithmetic Operators

The use of arithmetic operators such as add, sub, mul, div, and mod in filter expressions is not supported.

2.3.4 Sorting

To sort the result, use the $orderby query option (for example, ?$orderby=Name and ?$orderby=BirthPlace/CityName).

The default sort direction is ascending. You can make this explicit as follows: ?$orderby=Name asc.

You can also order the result in descending direction (for example, ?$orderby=Name desc).

To sort on multiple attributes, separate each attribute with a comma (for example, ?$orderby=Name asc,Age desc).

2.3.5 Selecting fields

To select which attributes and associations to return, specify the $select query option (for example, ?$select=Name,Age).

2.3.6 Paging

Paging enables loading data incrementally to better handle large amounts of data. Paging occurs when the client requests a lot of data, and the server returns a subset and a link to request the rest.

2.3.6.1 Top (Limit)

To limit the number of returned objects, use the $top query option. The limit (the number of objects to return) must be a positive integer. For example, ?$top=100 returns the top 100 objects in the list.

2.3.6.2 Skip (Offset)

To skip a number of objects before retrieving the result, use the $skip query option. The offset (the number of objects to skip) must be a positive integer. For example, ?$skip=100 returns objects starting with the 101st object in the list.

2.3.7 Null Literals

You can compare values against the null literal. For example, given a string attribute Name, you can use ?$filter=Name eq null to query for the objects that have no value assigned to the Name attribute.

Null literals are especially useful when you filter against associations. For example, with ?$filter=Association_A_B ne null, you can query for objects of entity type A that have at least one association set to objects of entity type B.

2.3.8 Passing Query Options in the Request Body

If the OData query is too long to be sent as a GET request, you can send the query as a POST request to the /$query endpoint. For example, POST /Products/$query with $select=Name,Price in the request body gives the same result as GET /Products?$select=Name,Price. These POST requests must specify the header Content-Type: text/plain.

3 Updating Objects

3.1 Updating Attributes

When a published entity has the Updatable capability, you can update attributes and associations by sending a PATCH request to the URL of the object. Here is an example: PATCH /odata/myservice/v1/Employees(8444249301330581).

Specify new values for attributes in the body of the request. Here is an example:

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{
  "Name": "John",
  "FirstContact": "2012-12-03T07:16:23Z",
  "DateOfBirth": null
}

3.1.1 Updating Attributes of Enumeration Type

To update attributes of an enumeration type, specify the exposed value of the enumeration in the body of the PATCH request. Do not include the prefix of the enumeration type.

So, for an attribute of type Country with values MyModule.Country.FR, MyModule.Country.BR, and MyModule.Country.JP (exposed as France, Brazil, and Japan, respectively), you can update your object as follows:

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{
  "Country": "Brazil"
}

3.2 Updating Associations

When the association refers to a single object, use the @id syntax to set an associated object, or use null to empty the associated object. Here is an example:

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{
  "Birthplace": { "@id": "Cities(511342)" },
  "Region": null
}

When the association refers to multiple objects, use the @delta syntax to add objects or remove objects from the association.

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{
  "Customers@delta": [
    {
      "@id": "Customers(484)"
    },
    {
      "@removed": {
        "reason": "changed"
      },
      "@id": "Customers(712)"
    }
  ]
}

4 Inserting Objects

When a published entity has the Insertable capability, you can create new objects by sending a POST request to the URL of the entity set. Here is an example: POST /odata/myservice/v1/Employees.

The body of the request may specify attribute and association values, just as with updates. However, unlike with updates, the @delta syntax is not used to specify objects, even when the association refers to multiple objects. Here is an example:

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{
  "Customers": [
    { "@id": "Customers(484)" },
    { "@id": "Customers(712)" }
  ]
}

You can set values for an association only from the entity that is the owner.

5 Deleting Objects

When a published entity has the Deletable capability, you can delete an object by sending a DELETE request to the URL of the object (for example, PATCH /odata/myservice/v1/Employees(8444249301330581)).

6 Calling Microflows

To call microflows that are published in your OData service, send a POST request to the action’s endpoint URL (for example, POST /odata/myservice/v1/OnboardNewEmployee).

The endpoint URL is defined by the base URL of the OData service and the exposed name of the microflow. To find an example URL, you can open the Edit published microflow dialog box and look at the Example of location property.

The request body is always a JSON object, with a property for each parameter that is defined in the published microflow. Here is an example:

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{
  "FirstName": "John",
  "LastName": "Doe",
  "FirstWorkingDay": "20240101T00:00:00.000Z",
  "CreatePayrollAccount": true
}

If a parameter’s data type is object, the value of the parameter’s property is a JSON object. If a parameter’s data type is list, the value of the parameter’s property is a JSON array. This is similar to what is expected when inserting objects for that entity.

For parameters whose type is an entity with the Readable capability, you can pass an existing object. Use the @id syntax to reference the object. When you pass an object using the @id reference, you can also pass attributes of the object; this assigns the specified attribute values to the existing object. Here is an example that passes the Employees(1783) object while specifying a value for the Email attribute:

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{
  "OffboardingDate": "20231231T00:00:00.000Z",  
  "Employee": {
    "@id": "Employees(1783)",
    "Email": "john.doe.personal@gmail.com"
  }
}

If the referenced object cannot be found, the action will fail.

When you pass a value for an attribute that is not writable—such as AutoNumber, Binary attributes, calculated attributes, and system attributes—the value is ignored and the object is passed to the microflow with the default value (for new objects) or the previous value (for existing objects). If it is an attribute that is writable but the current user does not have write rights for that member, the request will fail.

If the action returns a value, it will always be contained in a JSON object with a single property named value.