A client was asking for a connectable web part, sending a parameter to data form web part (dfwp) build by SharePointDesigner.
The first you will read on Microsoft msdn for SharePoint 2010 about this requirement should be: http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.webpartpages.communication.iparametersoutprovider.aspx.
Uups, there is a bold NOTE: This API is now obsolete (IParametersOutProvider) and where is the link to the new one? .. i was adapting the example for my test solution.
If i copied the complete code to my own web part class and compile this code first time, i got a message on my classname: ‘Microsoft.SharePoint.WebPartPages.Communication.IParametersOutProvider’ is obsolete: ‘Use System.Web.UI.WebControls.WebParts.IWebPartParameters instead’, why it’s not written in the note?
Trying this code, i was running in an unhandled exception on Step #6. The PartCommunicationConnect was called, the given connectedPart was Null! The exception occurs if you connect a dfwp with parameter binding to my wp implementing IParametersOutProvider. So i realized, this should not my solution.. searching for a fully description on IWebPartParameters.. there are not so many complete stories on the net yet..
Now i will share working c# code like in the above link.
In my example, a hidden web part extracts a sequence from current web URI and send the ‘data’ parameter to a dfwp connected by parameter binding.
1: // Common .NET required namespaces
2: using System;
3: using System.ComponentModel;
4:
5: // WebPart required namespaces
6: using System.Web;
7: using System.Web.UI;
8: using System.Web.UI.WebControls;
9: using System.Web.UI.WebControls.WebParts;
10:
11: //Step #1: Reference the SharePoint namespace.
12: using Microsoft.SharePoint;
13:
14: namespace ConnectionCodeSamples.WebPartParametersProvider
15: {
16: // Step #2: Inherit from the WebPart base class and implement the
17: // IWebPartParameters interface.
18: [ToolboxItemAttribute(false)]
19: public class WebPartParametersProvider : WebPart, IWebPartParameters
20: {
21: // Step #3: Declare private variables for configuration , handling
22: // and a value passed as parameter.
23: private int _strFirst;
24: private int _strLength;
25: private string _myError = string.Empty;
26:
27: private string _urlData = "WebPartParametersProvider url 'data' value";
28:
29: // Step #4: the provider must implement a list of property descriptors
30: // that the consumer is interested in
31: private PropertyDescriptorCollection _objParameters;
32: public PropertyDescriptorCollection Parameters
33: {
34: get { return _objParameters; }
35: set { _objParameters = value; }
36: }
37:
38: // Step #5: Constructor
39: public WebPartParametersProvider()
40: {
41: this.ExportMode = WebPartExportMode.All;
42: base.Hidden = true;
43: }
44:
45: // Step #6: implement ConnectionInterface
46: [ConnectionProvider("my parameters provider")]
47: public IWebPartParameters ConnectionInterface()
48: {
49: return this;
50: }
51:
52: // Step #7: implement a schema for the data returned by the provider
53: // you need this for the IWebPart* interfaces
54: public System.ComponentModel.PropertyDescriptorCollection Schema
55: {
56: get
57: {
58: PropertyDescriptorCollection objProperties;
59: PropertyDescriptor[] arrProperties =
60: new PropertyDescriptor[Parameters.Count];
61: TypeDescriptor.GetProperties(this);
62:
63: objProperties = TypeDescriptor.GetProperties(this);
64: int intParameterCount = 0;
65: foreach (PropertyDescriptor objProperty in Parameters)
66: {
67: if (Parameters[objProperty.Name] != null)
68: {
69: intParameterCount++;
70: arrProperties[intParameterCount] = objProperty;
71: }
72: }
73:
74: objProperties = new PropertyDescriptorCollection(arrProperties);
75: return objProperties;
76: }
77: }
78:
79: // Step #8: implement a method called SetConsumerSchema(), allows a consumer
80: // to express its interest in a set of parameters provided by provider
81: public void SetConsumerSchema(System.ComponentModel.PropertyDescriptorCollection schema)
82: {
83: Parameters = schema;
84: }
85:
86: // Step #9: implement the GetParametersData(), this will hold a reference
87: // to the parameters consumer web part after a connection is established
88: public void GetParametersData(ParametersCallback callback)
89: {
90: StateBag objParameters = new StateBag();
91:
92: foreach (PropertyDescriptor objProperty in Parameters)
93: {
94: switch (objProperty.Name)
95: {
96: case "data":
97: objParameters.Add("data", UrlData);
98: break;
99: default:
100: throw new Exception("WebPartParametersProvider: Unknown parameter name");
101: }
102: }
103:
104: callback.Invoke(objParameters);
105: }
106:
107: // Step #10: implement properties for web part configuration
108: // and to hold our data extracted from current url
109: [WebBrowsable(true),
110: Personalizable(PersonalizationScope.Shared),
111: WebDescription("The first char in web url to search for (0 based).")]
112: public int UrlFirst
113: {
114: get
115: {
116: return this._strFirst;
117: }
118: set
119: {
120: this._strFirst = value > 0 ? value : 0;
121: }
122: }
123:
124: [WebBrowsable(true),
125: Personalizable(PersonalizationScope.Shared),
126: WebDescription("The length of the string to extract after first char.")]
127: public int StrLength
128: {
129: get
130: {
131: return this._strLength;
132: }
133: set
134: {
135: this._strLength = value > 0 ? value : 0;
136: }
137: }
138:
139: public string UrlData
140: {
141: get { return _urlData; }
142: set { _urlData = value; }
143: }
144:
145: // Step #11: init the all data
146: protected override void OnInit(EventArgs e)
147: {
148: base.OnInit(e);
149:
150: if (UrlFirst != 0 && StrLength > 0)
151: {
152: try
153: {
154: string url = SPContext.Current.Web.Url;
155: if (url.Length >= UrlFirst + StrLength)
156: {
157: _urlData = url.Substring(UrlFirst, StrLength);
158: }
159: }
160: catch (Exception se)
161: {
162: _myError = se.Message + ", " + se.InnerException;
163: }
164: }
165: }
166:
167: // Step #12: create controls to show properies,
168: // data and web part configuration hints in page edit mode
169: protected override void CreateChildControls()
170: {
171: Controls.Clear();
172:
173: if ((UrlFirst == 0 || StrLength == 0))
174: {
175: //.. show a how to configure web part
176: }
177: else
178: {
179: //.. show your properties and the assigned data
180: }
181: }
182: }
183: }
for more description, please study also on msdn the IWebPartParameters interface: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.webparts.iwebpartparameters.aspx