Always test isMultiValued() in TableViewForm

api/src/org/labkey/api/data/AbstractWrappedColumnInfo.java

@@ -848,10 +848,4 @@ public boolean isMultiValued()
     {
         return delegate.isMultiValued();
     }
-
-    @Override @Transient
-    public final SimpleConvert getConvertFn()
-    {
-        return ColumnRenderProperties.getDefaultConvertFn(this);
-    }
 }

api/src/org/labkey/api/data/BaseColumnInfo.java

@@ -75,7 +75,6 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
-import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
 
 /**
@@ -2233,10 +2232,4 @@ public void setRemapMissingBehavior(SimpleTranslator.RemapMissingBehavior missin
     {
         _remapMissingBehavior = missingBehavior;
     }
-
-    @Override @Transient
-    public final SimpleConvert getConvertFn()
-    {
-        return ColumnRenderProperties.getDefaultConvertFn(this);
-    }
 }

api/src/org/labkey/api/data/ColumnInfo.java

@@ -15,6 +15,7 @@
  */
 package org.labkey.api.data;
 
+import org.apache.commons.beanutils.ConversionException;
 import org.apache.commons.lang3.StringUtils;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -457,6 +458,30 @@ static String toString(ColumnInfo col)
 
         return sb.toString();
     }
+
+    /// The returned Function<Object,Object> should throw ConversionException (undeclared RuntimeException).
+    /// This method does not handle compound conversions e.g. MissingValues or Out-of-range indicators.
+    /// Also, converting the pieces of a MVFK column is handled by QUS.
+    @Override
+    @Transient
+    default SimpleConvert getConvertFn()
+    {
+        return getDefaultConvertFn(this);
+    }
+
+    @Override
+    default Object convert(Object o) throws ConversionException
+    {
+        return getConvertFn().convert(o);
+    }
+
+    static SimpleConvert getDefaultConvertFn(ColumnInfo col)
+    {
+        // NOTE for MultiValued columns e.g. col.isMultiValued() || col.getFk() instanceof MultiValuedForeignKey
+        // MultiValuedDisplayColumn currently relies on the parent fk column hanldling convert from String to the element type (see MultiValuedRenderContext.get())
+        // However, This behavior is obviously wrong for MVFC that support insert/update, callers must be aware of this unfortunately (e.g. TableViewForm and CoerceDataIterator)
+        return ColumnRenderProperties.getDefaultConvertFn(col);
+    }
 }
 
 

api/src/org/labkey/api/data/MultiChoice.java

@@ -525,7 +525,7 @@ public ResultSet getResultSet(long index, int count, Map<String, Class<?>> map)
     }
 
 
-    public static class Converter implements org.apache.commons.beanutils.Converter, Function<Object,Object>
+    public static class Converter implements org.apache.commons.beanutils.Converter, SimpleConvert
     {
         private Converter()
         {
@@ -558,7 +558,7 @@ public <T> T convert(Class<T> aClass, Object o)
         }
 
         @Override
-        final public Object apply(Object o)
+        final public Object convert(Object o)
         {
             return convert(MultiChoice.Array.class, o);
         }

api/src/org/labkey/api/data/SimpleConvert.java

@@ -23,4 +23,6 @@ default SimpleConvert getConvertFn()
     {
         return this;
     }
+
+    SimpleConvert identity = (v) -> v;
 }

api/src/org/labkey/api/data/TableViewForm.java

@@ -417,16 +417,9 @@ protected void _populateValues(BindException errors)
 
             try
             {
-                Object val;
                 if (col != null)
-                {
                     propType = col.getJavaClass();
-                    val = col.convert(bindValue);
-                }
-                else
-                {
-                    val = getSimpleConvert(propName).convert(bindValue);
-                }
+                Object val = getSimpleConvert(propName).convert(bindValue);
 
                 boolean requiredError = false;
                 if (_validateRequired && null != _tinfo && null != col && col.isRequired() && !col.isAutoIncrement())