I have problem with angular material table datasource

I am using angular4-material table from this reference

I have an object which is coming from my back-end API but when I try to create the table data source with the following arguments I don’t see any data coming inside the testDataSource. When I inspect the element in debug mode the data field doesn’t have any data

this.testDataSource = new TableDataSource<any>(this.testItems, TestModel, this.testValidator);

Data inside this.testItems is a simple object with 10 fields.

Also could someone please suggest how to set an object to send it to my back-end rest API to save and update in to database

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