Question

Previously, I ran into a problem trying to share a type definition between my ASMX webservice and my .aspx page (webclient)

Confused on C# Array of objects and implicit type conversion

As I understand the advice, the ‘problem’ this creates can be solved by copying the array of objects created in the client to a new array of objects as defined by the ASMX proxy class.

Being a rookie in C# I am still struggling with this simple task. Here are more parts of my code (the other fragments in the previous post remain unchanged):

… here is where I populate the ‘test data’ I want to pass to the web service:

// create an array of MetaData objects MetaData[] nvPairs = new MetaData[20];   // arbitrary length of 20 pairs  // create arbitrary MetaData objects in the array nvPairs[0] = new MetaData('Grant Number', '2577-9912'); nvPairs[1] = new MetaData('OPEAnalyst', 'Simpson'); 

… here I attempt a function to ‘copy’ from ‘real’ type defined in my TRIMBrokerUtil namespace (which I can’t use completely because of the proxy) to the proxy version of that type:

protected TRIMBrokerASMXProxy.ASMXProxy.MetaData[] CopyMetaData(     MetaData utilArray) {     TRIMBrokerASMXProxy.ASMXProxy.MetaData[] outArray =          new TRIMBrokerASMXProxy.ASMXProxy.MetaData[utilArray.Name.Length];     int i;     for (i = 0; i < utilArray.Name.Length; i++)     {         outArray[i].Name = utilArray.Name;         outArray[i].Value = utilArray.Value;     }     return outArray; } 

… and then here is where I try to call that function (compiler flags 2 errors on this line:

TRIMBrokerASMXProxy.ASMXProxy.MetaData[] kvData =      CopyMetaData(metaDataArray);  

Both of the compile errors below point to the same line:

Error 1 The best overloaded method match for ‘_Default.CopyMetaData(TRIMBrokerUtil.MetaData)’ has some invalid arguments

Error 2 Argument ‘1’: cannot convert from ‘TRIMBrokerUtil.MetaData[]’ to ‘TRIMBrokerUtil.MetaData’

Am I close ?

Answer 1

You’ve declared your parameter to be MetaData rather than MetaData[] – in other words it’s not an array. You’re then using utilArray.Name rather a lot, but it’s not clear why.

I suspect you actually want:

protected TRIMBrokerASMXProxy.ASMXProxy.MetaData[]     CopyMetaData(MetaData[] utilArray) {     TRIMBrokerASMXProxy.ASMXProxy.MetaData[] outArray =          new TRIMBrokerASMXProxy.ASMXProxy.MetaData[utilArray.Length];     for (int i = 0; i < utilArray.Length; i++)     {         outArray[i] = new TRIMBrokerASMXProxy.ASMXProxy.MetaData();         outArray[i].Name = utilArray[i].Name;         outArray[i].Value = utilArray[i].Value;     }     return outArray; } 

By the way, you might want to consider a using directive to make this easier to read:

using ProxyMetaData = TRIMBrokerASMXProxy.ASMXProxy.MetaData;  ...  protected ProxyMetaData[] CopyMetaData(MetaData[] utilArray) {     ProxyMetaData[] outArray = new ProxyMetaData[utilArray.Length];     for (int i = 0; i < utilArray.Length; i++)     {         outArray[i] = new ProxyMetaData();         outArray[i].Name = utilArray[i].Name;         outArray[i].Value = utilArray[i].Value;     }     return outArray; } 

Another alternative is Array.ConvertAll:

ProxyMetaData[] output = Array.ConvertAll(input,     metaData => new ProxyMetaData(metaData.Name, metaData.Value)); 

If you’re not using C# 3 you can use an anonymous method for that. If ProxyMetaData doesn’t have an appropriate constructor and you are using C# 3, you can use an object initializer:

ProxyMetaData[] output = Array.ConvertAll(input,     metaData => new ProxyMetaData { metaData.Name, metaData.Value }); 

If you’re stuck with C# 2 and no appropriate constructor, then:

ProxyMetaData[] output = Array.ConvertAll(input, delegate(MetaData metaData) {     ProxyMetaData proxy = new ProxyMetaData();     proxy.Name = metaData.Name;     proxy.Value = metaData.Value; }); 

I think that’s covered all the bases 🙂