Multi-level linkage extension implementation in MVC (non-recursive form) and mvc Recursion

Multi-level linkage extension implementation in MVC (non-recursive form) and mvc Recursion

The MVC front-end interface is called as follows:

 @Html.AreaDropDownList("areaCode", areaCode, 3, string.Empty)

Parameter description:

The name of the first parameter control;
The region code selected by the second parameter;
Third parameter region level;
The fourth parameter is the root-level region;

The region database table is designed as follows:

Extension of the drop-down list:

1 # region drop-down list 2 3 /// <summary> 4 // linkage drop-down list 5 /// </summary> 6 /// <param name = "htmlHelper"> extended HtmlHelper instance </param> 7 // <param name = "expression"> get data set </param> 8 /// <param name = "level"> display level </param> 9 // <param name = "defaultValue"> default value of the TProperty type (for example, the default value of the string type is "") </param> 10 /// <param name = "rootItems"> get the root-Level list data </param> 11 /// <param name = "getParentID"> get the list item </param> 12 // <param name = "g EtChildItems "> method for getting data sets in sublists </param> 13 // <param name =" getChildSelectDataUrl "> remote address for obtaining data in sublists </param> 14/ // <returns> html code </returns> 15 public static MvcHtmlString LinkageDropDownListFor <TModel, TProperty> (this HtmlHelper <TModel> htmlHelper, Expression <Func <TModel, TProperty> expression, TProperty defaultValue, int level, Dictionary <TProperty, string> rootItems, Func <TProperty, TProperty> getParentID, Func <TProperty, Dictionary <TProperty, string> getChildItems, string getChildSelectDataUrl, string optionLabel = "select") 16 {17 ModelMetadata metadata = ModelMetadata. fromLambdaExpression (expression, htmlHelper. viewData); 18 19 return LinkageDropDownList (htmlHelper, ExpressionHelper. getExpressionText (expression), (TProperty) metadata. model, defaultValue, level, rootItems, getParentID, getChildItems, get ChildSelectDataUrl, optionLabel ); 20} 21 22 23 // <summary> 24 // linkage drop-down list 25 /// </summary> 26 /// <param name = "htmlHelper"> expanded htmlHelper instance </param> 27 // <param name = "level"> display level </param> 28 /// <param name = "defaultValue"> TProperty type (For example, the default value of string is "") </param> 29 // <param name = "name"> drop-down list form item name </param> 30 /// <param name = "selectedValue"> currently selected value </param> 31 // <param name = "rootItems"> get the root-Level list data </param> 32 /// <Param name = "getParentId"> method for obtaining the ParentID of the list item </param> 33 // <param name = "getChildItems"> method for obtaining the data set in the sublist </param> 34 // <param name = "getChildSelectDataUrl"> remote address for obtaining child list data </param> 35 // <returns> html code </returns> 36 public static MvcHtmlString LinkageDropDownList <TProperty> (this HtmlHelper htmlHelper, string name, TProperty selectedValue, TProperty defaultValue, int level, Dictionary <TProperty, string> rootIte MS, Func <TProperty, TProperty> getParentId, Func <TProperty, Dictionary <TProperty, string> getChildItems, string getChildSelectDataUrl, string optionLabel = "select ") 37 {38 string fullName = htmlHelper. viewContext. viewData. templateInfo. getFullHtmlFieldName (name); 39 // select data init40 Stack <Dictionary <TProperty, string> stack = new Stack <Dictionary <TProperty, string> (); 41 42 // If a selected value exists, search for List 43 IList <TProperty> selectedValues = new List <TProperty> (); 44 if (selectedValue! = Null &&! SelectedValue. Equals (defaultValue) 45 {46 TProperty itemId = selectedValue; 47 TProperty parentItemId = getParentId (itemId); 48 while (! ItemId. Equals (defaultValue )&&! ParentItemId. equals (defaultValue) 49 {50 stack. push (getChildItems (parentItemId); 51 selectedValues. add (itemId); 52 itemId = parentItemId; 53 parentItemId = getParentId (itemId); 54} 55 if (rootItems. count ()> 0) 56 {57 TProperty rootId = getParentId (rootItems. first (). key); 58 if (! ItemId. equals (rootId) 59 {60 stack. push (rootItems); 61 selectedValues. add (itemId); 62} 63} 64} 65 else66 {67 TProperty rootItemID = rootItems. select (n => n. key ). firstOrDefault (); 68 stack. push (rootItems); 69} 70 71 // generate TAG 72 TagBuilder containerBuilder = new TagBuilder ("span"); 73 containerBuilder. mergeAttribute ("plugin", "linkageDropDownList"); 74 var data = new Dictionary <string, object> (); 75 data. tryAdd ("GetChildSelectDataUrl", getChildSelectDataUrl); 76 data. tryAdd ("ControlName", name); 77 data. tryAdd ("Level", level); 78 data. tryAdd ("OptionLabel", optionLabel); 79 data. tryAdd ("DefaultValue", defaultValue. toString (); 80 containerBuilder. mergeAttribute ("data", Json. encode (data); 81 int currentIndex = 0; 82 while (stack. count> 0) 83 {84 Dictionary <TProperty, string> dictionary = stack. pop (); 85 IEnumerable <SelectListItem> selectList = dictionary. select (n => new SelectListItem () {Selected = selectedValues. contains (n. key), Text = n. value, Value = n. key. toString ()}); 86 containerBuilder. innerHtml + = "\ r \ n" + htmlHelper. dropDownList (string. format ("{0 }_{ 1}", name, currentIndex), selectList, 87 optionLabel, new {@ class = "tn-dropdownlist"}); 88 currentIndex ++; 89} 90 containerBuilder. innerHtml + = "\ r \ n" + htmlHelper. hidden (name); 91 return MvcHtmlString. create (containerBuilder. toString (); 92} 93 94 # endregionView Code

 

External call implementation:

1 /// <summary> 2 // region drop-down list 3 /// </summary> 4 /// <param name = "htmlHelper"> extended htmlHelper instance </param> 5 // <param name = "expression"> select the lamda expression of the category attribute in the object </param> 6 /// <param name = "areaLevel"> Region level (site region configuration is used by default) </param> 7 // <param name = "rootAreaCode"> root-level region (default site region configuration) </param> 8 public static MvcHtmlString AreaDropDownListFor <TModel> (this HtmlHelper <TModel> htmlHelper, Expression <Func <TModel, string> exp Ression, int? AreaLevel = null, string rootAreaCode = null) 11 {12 string getChildAreasUrl = "/Channel/GetChildAreas"; // obtain the remote address of the sub-region, (AreaCode, name) JSON data 13 if (areaLevel = null) 15 {16 areaLevel = 0; // The region setting level can be obtained as a configuration file 17} 18 return htmlHelper. linkageDropDownListFor <TModel, string> (expression, string. empty, areaLevel. value: obtains the (AreaCode, name) Key-Value pairs of the root region, obtains the parent region of the currently selected region, and obtains the current Child region, getChildAreasUrl ); 21} 22 23 // <summary> 24 // area drop-down list 25 /// </summary> 26 // <param name = "htmlHelper"> extended htmlHelper instance </param> 27 // /<param name = "name"> Control name attribute </param> 28 // <param name = "name"> selected region code </param> 29 /// <param name = "areaLevel"> region level (default site configuration) </param> 30 // <param name = "rootAreaCode"> root-level region (site region configuration by default) </param> 31 public static MvcHtmlString AreaDropDownList (this HtmlHelper htmlHelper, string name, string value, int? AreaLevel = null, string rootAreaCode = null) 32 {33 string getChildAreasUrl = "/Channel/GetChildAreas"; // obtain the remote address of the sub-region, (AreaCode, name) JSON data 34 if (areaLevel = null) 36 {37 areaLevel = 0; // The region setting level can be obtained as a configuration file 38} 39 return htmlHelper. linkageDropDownList <string> (name, value, string. empty, areaLevel. value: obtains the (AreaCode, name) Key-Value pairs of the root-level region, obtains the parent region of the currently selected region, and obtains the current Child region of the selected region, getChildAreasUrl); 42}