- Created by Kirstin Seidel-Gebert, last modified by Annegret Bernhardt on Jun 02, 2022
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You can use the MongoDB adapter to interact with a MongoDB and to insert, get and manipulate documents.
MongoDBAdapter_CustomerData_Example
Using one of the find operations from the MongoDB adapter, you can retrieve data. MongoDB stores data in form of documents that are depicted in a JSON-like format. Queries always return one or more complete documents. For all actions that refer to existing documents, you need to provide a query string (queryString) to identify them. A query string contains all properties of the document you want to use for selection. Assume we have the following sample Customer document structure: The simplest way to create a query string is the following: Create an object having the structure of the document (Customer in the example). Set all query values to this object (the customerID in the example). Provide this object as queryString by converting it to JSON using classToExtendedJSON().{
"id": "ebd7c78b-44e0-4cbd-8164-d28431716942"
"name": "John Snow",
"company": "Winter & Partners",
"address": {
"street": "99, Malamute Street",
"city": "Anchorage, AK 99506",
"country:": "USA"
},
orderValue: "16323.00
}
The MongoDB adapter comes with three find operations: two returning the result set in different formats, one returning a handle to the result set.create queryData;
set queryData.id = customerID;
set queryString = queryData.classToExtendedJSON();
Name | Type | Description | |
---|---|---|---|
result | Array of String | An array of all resulting documents in JSON format. | The complete set of found documents in an array. |
result | Array of <document class> | An array of objects of an xUML class representing the document structure. This only makes sense if you know the structure of the documents you are accessing. | |
handle | A handle to a result set. This is helpful if
| You need to process the result set one by one using fetch. |
Refer to the reference of find operations and fetch operations for a detailed description of all parameters and options.
Selecting Output Data
MongoDB uses the concept of "projection" to define which properties should be selected from a document. The projection is supplied to the adapter call via the projection attribute of the MongoDBFindOptions.
The following rules apply to projections:
Rule | Example |
---|---|
You can select dedicated properties. |
|
You can select all properties and omit dedicated properties. |
|
You cannot mix both above mentioned rules. This will lead to an exception. |
|
You can select properties from within a structure. |
|
You cannot select all properties and omit dedicated properties from within a structure. This will be ignored. |
|
Sorting
You can sort the document list you get back from an adapter call by providing the sort attribute of MongoDBFindOptions. Parameter sort contains the document properties to sort by. Value 1 is ascending sorting, value -1 is descending sorting. The order of JSON properties reflects the sort hierarchy.
create options; set options.`sort` = "{\"company\":1,\"orderVolume\":-1}";
You can also create a class defining the sort options, and use classToExtendedJSON() to create the sort string.
You need to escape the attribute name of sort because there is an operation having the same name.
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