Are [FromBody] and [FromUri] mutually exclusive?

Question

I am passing this URI to my Web API server:

http://localhost:28642/api/InventoryItems/PostInventoryItem?serialNum=8675309e9&ID=147&pksize=2&Description=juanValdes&vendor_id=venderado&UnitCost=2.58&UnitList=3.82&OpenQty=25.70&UPC=12349&dept=139&subdept=89&upc_pack_size=24&vendor_item=popTartz&crv_id=157

This Controller code (with the "[FromBody]" annotation) does not work:

public void PostInventoryItem([FromBody] string serialNum, [FromUri] InventoryItem ii)
{
    string serNum = serialNum;
    _inventoryItemRepository.PostInventoryItem(serNum,
        ii.ID, ii.pksize, ii.Description, ii.vendor_id, ii.UnitCost, ii.UnitList, ii.OpenQty,
        ii.UPC, ii.dept, ii.subdept, ii.upc_pack_size, ii.vendor_item, ii.crv_id);
}

...(serialNum is null); but this (without the "[FromBody]" annotation) does:

public void PostInventoryItem(string serialNum, [FromUri] InventoryItem ii)
{
    string serNum = serialNum;
    _inventoryItemRepository.PostInventoryItem(serNum,
        ii.ID, ii.pksize, ii.Description, ii.vendor_id, ii.UnitCost, ii.UnitList, ii.OpenQty,
        ii.UPC, ii.dept, ii.subdept, ii.upc_pack_size, ii.vendor_item, ii.crv_id);
}

(serialNum is the expected "8675309e9") Why? One would think the more specific version would work but, although it compiles, serialNum is null with that first snippet.

I know you can't use two "[FromBody]" annotations in one method, as noted here, but is it the case that all other annotations are disallowed?

Answer 1

In your first implementation

public void PostInventoryItem([FromBody] string serialNum, [FromUri] InventoryItem ii)

{}

the value of serialNum is null as expected, because [FromBody] was trying to look for serialNum in the body of your message.

This is the definition of the attribute from MSDN:

FromBodyAttribute Class

An attribute that specifies that an action parameter comes only from the entity body of the incoming HttpRequestMessage.