# GenApi StringNode Value Access

**URL:** <https://forum.commonvisionblox.com/t/genapi-stringnode-value-access/263>\
**Category:** C++ API\
**Tags:** genapi\
**Created:** [November 8, 2017, 4:06pm UTC](https://forum.commonvisionblox.com/t/genapi-stringnode-value-access/263 "2017-11-08T16:06:16Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![gerd](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.commonvisionblox.com/gerd/32/233_2.png) [@gerd](https://forum.commonvisionblox.com/u/gerd)\
**Post date:** [November 8, 2017, 4:06pm UTC](https://forum.commonvisionblox.com/t/genapi-stringnode-value-access/263/1 "2017-11-08T16:06:16Z")

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Hello together,

I want to access the values of _StringNodes_ that are located in the Device Nodemap of a camera.  
Therefore my approach is as follows:

```cpp
    //Path to VIN
    Cvb::String path(CVB_LIT("%CVB%Drivers\\GenICam.vin"));
    path = Cvb::ExpandPath(path);
    
    //Open Device
    device = Cvb::DeviceFactory::Open(path);
    
    //Get NodeMap
    Cvb::String nodeMapName(CVB_LIT("Device"));
    auto nodeMap = device->NodeMap(nodeMapName);
    
    // A) Access value using Cvb::StringNode
    Cvb::StringNode vendorNameNode = nodeMap->Node(Cvb::String(CVB_LIT("Std::DeviceVendorName"))).get()

    // B) Acces value using C-style Api
    NODEMAP nodeMapCApi = nodeMap->Handle();
    NODE deviceVendorNameNode;    
    cvbres_t restulT = NMGetNode(nodeMapCApi, "DeviceVendorName", deviceVendorNameNode);

    size_t strSize; 
    NGetAsString(deviceVendorNameNode, NULL, strSize);
    char* tmpStr= (char *)malloc(strSize * sizeof(char*));

    NGetAsString(deviceVendorNameNode, tmpStr, strSize);

```

The access of the value using the _C-Style Api_ (B) after receiving the handle from _Cvb::NodeMap_ works fine but the access of the value using _Cvb::StringNode_ (A) leads to an empty value.  
Is it programmatically correct to pass the result of a _`shared_ptr*<Cvb::GenApi::Node>::get()`_ to a _`Cvb::StringNode`_ instance or am I wrong here?

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**Author:** ![Andreas](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.commonvisionblox.com/andreas/32/75_2.png) [@Andreas](https://forum.commonvisionblox.com/u/Andreas)\
**Post date:** [November 8, 2017, 8:31pm UTC](https://forum.commonvisionblox.com/t/genapi-stringnode-value-access/263/2 "2017-11-08T20:31:34Z")

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Let me rewrite your spinet line and hopefully clear some misconceptions.

```auto

// CVB_LIT is only usfull if your code must compile with wide strings and 
// Unicode (usually on Windows and Linux), So it only makes sense 
// together with a compatible path notation (lower-case and forward slash)! 
auto device = Cvb::Device::Open(Cvb::ExpandPath(CVB_LIT("%CVB%/drivers/GenICam.vin")));

// You can always pass your literals directly, if not it is a bug on our side! 
auto deviceNodeMap = device->NodeMap(CVB_LIT("Device"));

// Your A) will not compile as types do not match.
// If you need the a node's value you should provide the type alongside 
// NodeMap::Node, to automatically cast the node to the wanted type.
// Without casting you will only get the base node type.  
auto stringNode = deviceNodeMap->Node<Cvb::StringNode>(CVB_LIT(DeviceVendorName));

// Get the actual value. 
// Note: it is not recommended to mix classic C-API and the object oriented wrappers.
// The only reason to do so, is because the wrappers are still missing some features! 
auto value = stringNode->Value();

```

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<div class="post-metadata">

**Author:** ![illusive](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.commonvisionblox.com/illusive/32/61_2.png) [@illusive](https://forum.commonvisionblox.com/u/illusive)\
**Post date:** [November 9, 2017, 8:18am UTC](https://forum.commonvisionblox.com/t/genapi-stringnode-value-access/263/3 "2017-11-09T08:18:43Z")

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In addition to what @Andreas wrote: It is generally not a good idea to mix the next-gen APIs with the classic API. In principle it’ll work, but one would have to be aware of the ways in which the next-gen APIs handle object ownership, otherwise it’ll be easy to mess things up pretty badly.

Generally speaking: Whenever you have a feeling that there might be something missing in the next-gen API, then point it out to us rather than looking for a workaround that might be very frustrating to implement and/or debug.

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<div class="post-metadata">

**Author:** ![illusive](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.commonvisionblox.com/illusive/32/61_2.png) [@illusive](https://forum.commonvisionblox.com/u/illusive)\
**Post date:** [May 14, 2019, 2:48pm UTC](https://forum.commonvisionblox.com/t/genapi-stringnode-value-access/263/4 "2019-05-14T14:48:53Z")

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Just to clarify: Mixing the [CVB.Net](http://CVB.Net), CVB++ or CVBpy APIs with the C-API of tools that are not (yet) covered by these new APIs by means of passing the handles of the underlying objects to the C functions is generally ok. But mixing the C-API with the [CVB.Net](http://CVB.Net), CVB++ or CVBpy API where the same functionality is covered (e. g. by handling nodemap access partly through the CVB++ classes and partly through the header _iCVGenApi.h_) should be approached with extreme caution…