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后备命令处理_add-fallback-commands
以下为本文档的中文说明该技能指导开发者如何为VS Code命令面板Command Palette扩展添加后备命令功能实现全面搜索行为。当用户在命令面板中输入的查询无法匹配任何顶层命令时后备命令会被触发使扩展能充当全面处理器。使用场景包括创建公式计算器输入即计算、网页搜索扩展对未匹配的查询直接发起搜索、文件路径打开器直接解析输入为路径、shell命令执行器从搜索栏运行系统命令以及任何需要捕获用户全部输入的场景。核心特点在于其无干扰的触发机制用户无需选择特定扩展或调用特定命令只要输入的查询没有命中其他扩展的顶层命令后备命令就会自动生效。Microsoft官方内置的20个扩展中有14个使用了该机制足以证明其成熟度。工作流程简单清晰用户在命令面板键入查询如果无顶层命令匹配CmdPal向扩展请求后备结果扩展通过FallbackCommands()提供匹配项并显示给用户。核心原则是’最后的匹配者’——后备命令应当处理其他扩展都不处理的搜索查询而非抢在常规命令之前拦截输入。该技能还涵盖如何控制后备命令的触发优先级、如何显示进度反馈以应对耗时的后备查询以及如何避免与现有命令产生冲突的最佳实践。Add Fallback CommandsFallback commands are shown in Command Palette when no other results match the user’s query. They enable your extension to act as a catch-all handler — perfect for calculators, web search, command execution, file path opening, and more.When to Use This SkillAdding search functionality that responds to any user inputCreating a calculator that evaluates expressions as the user typesBuilding a web search that triggers on unmatched queriesOpening files or URLs typed directly into the paletteExecuting shell commands from the search barHow Fallback Commands WorkUser types a query in Command PaletteIf no top-level commands match, CmdPal asks extensions for fallback resultsYour extension’sFallbackCommands()provides items that respond to the queryThe fallback items can be static (always shown) or dynamic (filtered by query)Quick Start: Static FallbackOverrideFallbackCommands()in yourCommandProvider:publicpartialclassMyCommandsProvider:CommandProvider{privatereadonlyICommandItem[]_commands;privatereadonlyFallbackCommandItem[]_fallbacks;publicMyCommandsProvider(){DisplayNameWeb Search;IconnewIconInfo(\\uE721);// Search iconvarsearchPagenewWebSearchPage();_commands[newCommandItem(searchPage){TitleDisplayName}];_fallbacks[newFallbackCommandItem(searchPage){TitleSearch the web}];}publicoverrideICommandItem[]TopLevelCommands()_commands;publicoverrideIFallbackCommandItem[]FallbackCommands()_fallbacks;}Dynamic Fallback with DynamicListPageFor fallbacks that filter results based on the query, useDynamicListPage:internalsealedpartialclassWebSearchPage:DynamicListPage{privatestring_querystring.Empty;publicWebSearchPage(){IconnewIconInfo(\\uE721);TitleWeb Search;NameSearch;PlaceholderTextType to search...;}publicoverridevoidUpdateSearchText(stringoldSearch,stringnewSearch){_querynewSearch;RaiseItemsChanged();}publicoverrideIListItem[]GetItems(){if(string.IsNullOrWhiteSpace(_query))return[];return[newListItem(newOpenUrlCommand($https://www.google.com/search?q{Uri.EscapeDataString(_query)})){Title$Search Google for \\{_query}\\,IconnewIconInfo(\\uE721),},newListItem(newOpenUrlCommand($https://www.bing.com/search?q{Uri.EscapeDataString(_query)})){Title$Search Bing for \\{_query}\\,IconnewIconInfo(\\uE721),},];}}Responsive Fallback with CancellationFor expensive operations (API calls, file searches), use cancellation to stay responsive:internalsealedpartialclassSmartSearchPage:DynamicListPage{privateCancellationTokenSource?_cts;privateIListItem[]_results[];publicoverridevoidUpdateSearchText(stringoldSearch,stringnewSearch){// Cancel any in-flight search_cts?.Cancel();_ctsnewCancellationTokenSource();vartoken_cts.Token;_Task.Run(async(){// Debounce: wait for user to stop typingawaitTask.Delay(300,token);if(token.IsCancellationRequested)return;// Perform search_resultsawaitSearchAsync(newSearch,token);RaiseItemsChanged();},token);}publicoverrideIListItem[]GetItems()_results;privateasyncTaskIListItem[]SearchAsync(stringquery,CancellationTokentoken){// Your search logic here// Check token.IsCancellationRequested periodicallyreturn[];}}Real-World Examples (from built-in extensions)| Extension | Fallback Behavior ||-----------|------------------||Apps| Search installed applications by name ||Calc| Evaluate mathematical expressions directly ||Shell| Execute command-line commands ||WebSearch| Search the web with configured engine ||Indexer| Open files by path ||TimeDate| Parse time/date queries ||WindowsSettings| Jump to Windows Settings pages ||WinGet| Search WinGet packages ||WindowWalker| Find and switch to open windows |Key PointsFallbackCommands()returnsIFallbackCommandItem[](notICommandItem[])UseFallbackCommandItemwrapper (notCommandItem)Wrap aDynamicListPagefor query-reactive resultsCancel previous searches when new input arrivesKeep fallback responses fast — users expect instant resultsUsePlaceholderTexton your page to guide usersDocumentationExtension samplesExtensibility overview3c:[“ , ,,L3f”,null,{“content”:“$40”,“frontMatter”:{“name”:“add-fallback-commands”,“description”:“Add fallback commands to your Command Palette extension for catch-all search behavior. Use when asked to add search functionality, query matching, direct input handling, calculator-style evaluation, URL opening, command execution, or results that appear when no other extension matches. Used by 14 of 20 built-in extensions.”}}]3d:[“KaTeX parse error: Expected }, got EOF at end of input: …,children:[[”,“div”,null,{“className”:“flex items-center justify-between border-b border-border bg-muted/30 px-4 py-2.5”,“children”:[[“KaTeX parse error: Expected }, got EOF at end of input: …,children:[”,“span”,null,{“className”:“truncate text-xs font-medium text-muted-foreground”,“children”:“同仓库更多 Skills”}]}],[“KaTeX parse error: Expected EOF, got } at position 88: …ldren:同仓库}]]}̲],[”,“div”,null,{“className”:“p-4 sm:p-5”,“children”:[[“ , h 2 , n u l l , i d : r e l a t e d − s k i l l s − h e a d i n g , c l a s s N a m e : t e x t − 2 x l f o n t − s e m i b o l d t r a c k i n g − n o r m a l t e x t − f o r e g r o u n d , c h i l d r e n : 同仓库更多 S k i l l s ] , [ ,h2,null,{id:related-skills-heading,className:text-2xl font-semibold tracking-normal text-foreground,children:同仓库更多 Skills}],[,h2,null,id:related−skills−heading,className:text−2xlfont−semiboldtracking−normaltext−foreground,children:同仓库更多Skills],[”,“div”,null,{“className”:“mt-4 grid gap-3 sm:grid-cols-2”,“children”:[“L 41 , L41,L41,L42”,“L 43 , L43,L43,L44”,“L 45 , L45,L45,L46”]}]]}]]}]47:I[206516,[“/_next/static/chunks/051aanbhrv4br.js”,“/_next/static/chunks/0mizr60h7ayzt.js”,“/_next/static/chunks/0v9lm1dmbdoo-.js”,“/_next/static/chunks/0rxr1j1j3j-.r.js”,“/_next/static/chunks/02ftybezfvqjd.js”,“/_next/static/chunks/0.v9ksvnnj8ia.js”,“/_next/static/chunks/0bn6id96nx3k.js,“/_next/static/chunks/13ybnhn37c.tc.js”,“/_next/static/chunks/0_fnrdtruz8uf.js”,“/_next/static/chunks/0r6l15utt1mwb.js”,“/_next/static/chunks/0dm9a5into854.js”,/_next/static/chunks/07k6hqoibtcn.js”,“/next/static/chunks/0b4cao.4y…j.js”,“/_next/static/chunks/02i-n28z7kjd0.js”],“default”]
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