Merge pull request #32 from khalidabuhakmeh/mat-allow-existing-triggers

Allow existing triggers to be merged in with new trigger definitions

Author: khalidabuhakmeh

src/Htmx/HtmxResponseHeaders.cs

@@ -1,7 +1,9 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Text;
 using System.Text.Json;
+using System.Text.Json.Nodes;
 using JetBrains.Annotations;
 using Microsoft.AspNetCore.Http;
 
@@ -183,7 +185,7 @@ public HtmxResponseHeaders WithTrigger(string eventName, object? detail = null,
         }
         else
         {
-            _triggers[timing].Add(eventName, detail ?? string.Empty);
+            _triggers[timing].TryAdd(eventName, detail ?? string.Empty);
         }
 
         return this;
@@ -196,38 +198,66 @@ internal HtmxResponseHeaders Process()
     {
         if (_triggers.ContainsKey(HtmxTriggerTiming.Default))
         {
-            if (_headers.ContainsKey(Keys.Trigger))
-            {
-                throw new Exception("You must use either WithTrigger(..) or Trigger(..), but not both.");
-            }
+            ParsePossibleExistingTriggers(Keys.Trigger, HtmxTriggerTiming.Default);
 
             _headers[Keys.Trigger] = BuildTriggerHeader(HtmxTriggerTiming.Default);
         }
 
         if (_triggers.ContainsKey(HtmxTriggerTiming.AfterSettle))
         {
-            if (_headers.ContainsKey(Keys.TriggerAfterSettle))
-            {
-                throw new Exception("You must use either WithTrigger(..) or TriggerAfterSettle(..), but not both.");
-            }
+            ParsePossibleExistingTriggers(Keys.TriggerAfterSettle, HtmxTriggerTiming.AfterSettle);
 
             _headers[Keys.TriggerAfterSettle] = BuildTriggerHeader(HtmxTriggerTiming.AfterSettle);
         }
 
         // ReSharper disable once InvertIf
         if (_triggers.ContainsKey(HtmxTriggerTiming.AfterSwap))
         {
-            if (_headers.ContainsKey(Keys.TriggerAfterSwap))
-            {
-                throw new Exception("You must use either WithTrigger(..) or TriggerAfterSwap(..), but not both.");
-            }
+            ParsePossibleExistingTriggers(Keys.TriggerAfterSwap, HtmxTriggerTiming.AfterSwap);
 
             _headers[Keys.TriggerAfterSwap] = BuildTriggerHeader(HtmxTriggerTiming.AfterSwap);
         }
 
         return this;
     }
 
+    /// <summary>
+    /// Checks to see if the response has an existing header defined by headerKey.  If it does the
+    /// header loads all of the triggers locally so they aren't overwritten by Htmx.
+    /// </summary>
+    /// <param name="headerKey"></param>
+    /// <param name="timing"></param>
+    private void ParsePossibleExistingTriggers(string headerKey, HtmxTriggerTiming timing)
+    {
+        if (!_headers.ContainsKey(headerKey))
+            return;
+
+        var header = _headers[headerKey];
+        // Attempt to parse existing header as Json, if fails it is a simplified event key
+        // assume if the string starts with '{' and ends with '}', that it is JSON
+        if (header.Any(h => h is ['{', .., '}']))
+        {
+            var reader = new Utf8JsonReader(Encoding.UTF8.GetBytes(header));
+            // this might still throw :(
+            var jsonObject = JsonNode.Parse(ref reader)?.AsObject();
+            // Load any existing triggers
+            foreach (var (key, value) in jsonObject!) 
+                WithTrigger(key, value, timing);
+        }
+        else
+        {
+            foreach (var headerValue in _headers[headerKey])
+            {
+                if (headerValue is null) continue;
+
+                var eventNames = headerValue.Split(',');
+
+                foreach (var eventName in eventNames)
+                    WithTrigger(eventName, null, timing);
+            }
+        }
+    }
+
     private string BuildTriggerHeader(HtmxTriggerTiming timing)
     {
         // Reduce the payload if the user has only specified 1 trigger with no value

test/Htmx.Tests/HtmxHttpResponseExtensionsTests.cs

@@ -122,24 +122,47 @@ public void Can_add_multiple_triggers_with_detail()
     }
 
     [Fact]
-    public void Cant_use_legacy_trigger_and_with_trigger()
+    public void Can_use_existing_trigger_with_trigger()
     {
-        Response.Htmx(h => h.Trigger("cool"));
-        Assert.Throws<Exception>(() => Response.Htmx(h => h.WithTrigger("neat")));
+	    const string expected = @"{""neat"":"""",""cool"":""""}";
+
+	    Response.Htmx(h => h.WithTrigger("cool"));
+	    Response.Htmx(h => h.WithTrigger("neat"));
+
+	    Assert.True(Headers.ContainsKey(Keys.Trigger));
+	    Assert.Equal(expected, Headers[Keys.Trigger]);
     }
-        
+
     [Fact]
-    public void Cant_use_legacy_triggeraftersettle_and_with_trigger()
+    public void Can_use_existing_trigger_with_multiple_triggers_with_detail()
     {
-        Response.Htmx(h => h.TriggerAfterSettle("cool"));
-        Assert.Throws<Exception>(() => Response.Htmx(h => h.WithTrigger("neat", timing: HtmxTriggerTiming.AfterSettle)));
+	    const string expected = @"{""cool"":{""magic"":""something""},""neat"":{""moremagic"":false},""wow"":""""}";
+
+	    Response.Htmx(h => h.WithTrigger("wow"));
+	    Response.Htmx(h =>
+	    {
+		    h.WithTrigger("cool", new { magic = "something" });
+		    h.WithTrigger("neat", new { moremagic = false });
+	    });
+
+	    Assert.True(Headers.ContainsKey(Keys.Trigger));
+	    Assert.Equal(expected, Headers[Keys.Trigger]);
     }
-        
+
     [Fact]
-    public void Cant_use_legacy_triggerafterswap_and_with_trigger()
+    public void Can_use_existing_trigger_with_detail_with_multiple_triggers_with_detail()
     {
-        Response.Htmx(h => h.TriggerAfterSwap("cool"));
-        Assert.Throws<Exception>(() => Response.Htmx(h => h.WithTrigger("neat", timing: HtmxTriggerTiming.AfterSwap)));
+	    const string expected = @"{""cool"":{""magic"":""something""},""neat"":{""moremagic"":false},""wow"":{""display"":true}}";
+
+	    Response.Htmx(h => h.WithTrigger("wow", new { display = true }));
+	    Response.Htmx(h =>
+	    {
+		    h.WithTrigger("cool", new { magic = "something" });
+		    h.WithTrigger("neat", new { moremagic = false });
+	    });
+
+	    Assert.True(Headers.ContainsKey(Keys.Trigger));
+	    Assert.Equal(expected, Headers[Keys.Trigger]);
     }
 
     [Fact]