Add goverter:matchIgnoreCase

README.md

@@ -244,6 +244,37 @@ type Output struct {
 }
 ```
 
+### Case-insensitive field matching
+
+With `goverter:matchIgnoreCase` tag you can instruct goverter to perform case-insensitive mapping
+between source and target fields. If this tag is present on a conversion method, goverter matches
+the fields using strings.EqualFold method.
+
+Use this tag only when it is extremely unlikely for the source or the target to have two fields
+that differ only in casing. E.g.: converting go-jet generated model to protoc generated struct.
+If `matchIgnoreCase` is present and goverter detects an ambiquous match, it either prefers an exact
+match (if found) or reports an error. Use goverter:map to fix an ambiquous match error.
+
+`goverter:matchIgnoreCase` takes no parameters.
+
+```go
+// goverter:converter
+type Converter interface {
+    // goverter:matchIgnoreCase
+    // goverter:map  FullId FullID
+    Convert(source Input) Output
+}
+
+type Input struct {
+    Uuid string
+    FullId int
+    fullId int
+}
+type Output struct {
+    UUID string // auto-matched with Uuid due to goverter:matchIgnoreCase
+    FullID string // mapped to FullId, to resolve ambiguity
+}
+```
 
 #### Struct identity mapping
 

builder/builder.go

@@ -28,4 +28,5 @@ type MethodContext struct {
 	IdentityMapping map[string]struct{}
 	Signature       xtype.Signature
 	PointerChange   bool
+	MatchIgnoreCase bool
 }

builder/struct.go

@@ -78,18 +78,20 @@ func mapField(gen Generator, ctx *MethodContext, targetField *types.Var, sourceI
 
 	mappedName, hasOverride := ctx.Mapping[targetField.Name()]
 	if ctx.Signature.Target != target.T.String() || !hasOverride {
-		if fieldSource, ok := source.StructField(targetField.Name()); ok {
-			nextID := sourceID.Code.Clone().Dot(targetField.Name())
+		sourceMatch, err := source.StructField(targetField.Name(), ctx.MatchIgnoreCase, ctx.IgnoredFields)
+		if err == nil {
+			nextID := sourceID.Code.Clone().Dot(sourceMatch.Name)
 			lift = append(lift, &Path{
 				Prefix:     ".",
-				SourceID:   targetField.Name(),
-				SourceType: fieldSource.T.String(),
+				SourceID:   sourceMatch.Name,
+				SourceType: sourceMatch.Type.T.String(),
 				TargetID:   targetField.Name(),
 				TargetType: targetField.Type().String(),
 			})
-			return nextID, fieldSource, []jen.Code{}, lift, nil
+			return nextID, sourceMatch.Type, []jen.Code{}, lift, nil
 		}
-		cause := fmt.Sprintf("Cannot set value for field %s because it does not exist on the source entry.", targetField.Name())
+		// field lookup either did not find anything or failed due to ambiquous match with case ignored
+		cause := fmt.Sprintf("Cannot match the target field with the source entry: %s.", err.Error())
 		return nil, nil, nil, nil, NewError(cause).Lift(&Path{
 			Prefix:     ".",
 			SourceID:   "???",
@@ -122,12 +124,14 @@ func mapField(gen Generator, ctx *MethodContext, targetField *types.Var, sourceI
 				SourceType: "???",
 			}).Lift(lift...)
 		}
-		var ok bool
-		if nextSource, ok = nextSource.StructField(path[i]); ok {
-			nextID = nextID.Clone().Dot(path[i])
+		// since we are searching for a mapped name, search for exact match, explicit field map does not ignore case
+		sourceMatch, err := nextSource.StructField(path[i], false, ctx.IgnoredFields)
+		if err == nil {
+			nextSource = sourceMatch.Type
+			nextID = nextID.Clone().Dot(sourceMatch.Name)
 			liftPath := &Path{
 				Prefix:     ".",
-				SourceID:   path[i],
+				SourceID:   sourceMatch.Name,
 				SourceType: nextSource.T.String(),
 			}
 
@@ -142,7 +146,7 @@ func mapField(gen Generator, ctx *MethodContext, targetField *types.Var, sourceI
 			continue
 		}
 
-		cause := fmt.Sprintf("Mapped source field '%s' doesn't exist.", path[i])
+		cause := fmt.Sprintf("Cannot find the mapped field on the source entry: %s.", err.Error())
 		return nil, nil, []jen.Code{}, nil, NewError(cause).Lift(&Path{
 			Prefix:     ".",
 			SourceID:   path[i],

comments/parse_docs.go

@@ -44,8 +44,9 @@ type ConverterConfig struct {
 
 // Method contains settings that can be set via comments.
 type Method struct {
-	IgnoredFields map[string]struct{}
-	NameMapping   map[string]string
+	IgnoredFields   map[string]struct{}
+	NameMapping     map[string]string
+	MatchIgnoreCase bool
 	// target to source
 	IdentityMapping map[string]struct{}
 }
@@ -226,6 +227,12 @@ func parseMethodComment(comment string) (Method, error) {
 					m.IgnoredFields[f] = struct{}{}
 				}
 				continue
+			case "matchIgnoreCase":
+				if len(fields) != 1 {
+					return m, fmt.Errorf("invalid %s:matchIgnoreCase, parameters not supported", prefix)
+				}
+				m.MatchIgnoreCase = true
+				continue
 			}
 			return m, fmt.Errorf("unknown %s comment: %s", prefix, line)
 		}

generator/generator.go

@@ -24,6 +24,7 @@ type methodDefinition struct {
 	Mapping         map[string]string
 	IgnoredFields   map[string]struct{}
 	IdentityMapping map[string]struct{}
+	MatchIgnoreCase bool
 
 	Jen jen.Code
 
@@ -77,6 +78,7 @@ func (g *generator) registerMethod(methodType *types.Func, methodComments commen
 		Source:           xtype.TypeOf(source),
 		Target:           xtype.TypeOf(target),
 		Mapping:          methodComments.NameMapping,
+		MatchIgnoreCase:  methodComments.MatchIgnoreCase,
 		IgnoredFields:    methodComments.IgnoredFields,
 		IdentityMapping:  methodComments.IdentityMapping,
 		ReturnError:      returnError,
@@ -152,6 +154,7 @@ func (g *generator) buildMethod(method *methodDefinition) *builder.Error {
 		Mapping:         method.Mapping,
 		IgnoredFields:   method.IgnoredFields,
 		IdentityMapping: method.IdentityMapping,
+		MatchIgnoreCase: method.MatchIgnoreCase,
 		Signature:       xtype.Signature{Source: method.Source.T.String(), Target: method.Target.T.String()},
 	}
 	stmt, newID, err := g.buildNoLookup(ctx, xtype.VariableID(sourceID.Clone()), source, target)
@@ -232,6 +235,7 @@ func (g *generator) Build(ctx *builder.MethodContext, sourceID *xtype.JenID, sou
 		if ctx.PointerChange {
 			ctx.PointerChange = false
 			method.Mapping = ctx.Mapping
+			method.MatchIgnoreCase = ctx.MatchIgnoreCase
 			method.IgnoredFields = ctx.IgnoredFields
 		}
 

runner_test.go

@@ -75,7 +75,7 @@ func TestScenario(t *testing.T) {
 
 			if scenario.Error != "" {
 				require.Error(t, err)
-				require.Equal(t, replaceAbsolutePath(fmt.Sprint(err)), scenario.Error)
+				require.Equal(t, scenario.Error, replaceAbsolutePath(fmt.Sprint(err)))
 				return
 			}
 

scenario/3_struct_match_ignore_case.yml

@@ -0,0 +1,36 @@
+input:
+    input.go: |
+        package structs
+
+        // goverter:converter
+        type Converter interface {
+            // goverter:matchIgnoreCase
+            Convert(source Input) Output
+        }
+
+        type Input struct {
+            Name string
+            UUID string
+            OtherID int
+        }
+        type Output struct {
+            Name string
+            Uuid string
+            OtherId int
+        }
+success: |
+    // Code generated by github.com/jmattheis/goverter, DO NOT EDIT.
+
+    package generated
+
+    import execution "github.com/jmattheis/goverter/execution"
+
+    type ConverterImpl struct{}
+
+    func (c *ConverterImpl) Convert(source execution.Input) execution.Output {
+    	var structsOutput execution.Output
+    	structsOutput.Name = source.Name
+    	structsOutput.Uuid = source.UUID
+    	structsOutput.OtherId = source.OtherID
+    	return structsOutput
+    }

scenario/3_struct_match_ignore_case_ambiguous_ok.yml

@@ -0,0 +1,46 @@
+input:
+    input.go: |
+        package structs
+
+        // goverter:converter
+        type Converter interface {
+            // goverter:matchIgnoreCase
+            // goverter:map AmbID AmbId
+            // goverter:ignore Ambid2
+            Convert(source Input) Output
+        }
+
+        type Input struct {
+            OtherID string
+            OtherId int // should prefer exact match
+            Uuid string
+            AmbID float64 // explicit choice
+            Ambid float64
+            AmbID2 string
+            Ambid2 string
+        }
+        type Output struct {
+            OtherId int
+            Uuid string // should prefer exact match
+            UUID string
+            AmbId float64
+            AmbId2 string
+        }
+success: |
+    // Code generated by github.com/jmattheis/goverter, DO NOT EDIT.
+
+    package generated
+
+    import execution "github.com/jmattheis/goverter/execution"
+
+    type ConverterImpl struct{}
+
+    func (c *ConverterImpl) Convert(source execution.Input) execution.Output {
+    	var structsOutput execution.Output
+    	structsOutput.OtherId = source.OtherId
+    	structsOutput.Uuid = source.Uuid
+    	structsOutput.UUID = source.Uuid
+    	structsOutput.AmbId = source.AmbID
+    	structsOutput.AmbId2 = source.AmbID2
+    	return structsOutput
+    }

scenario/7_error_invalid_match_ignore_case_with_param.yml

@@ -0,0 +1,10 @@
+input:
+    input.go: |
+        package structs
+
+        // goverter:converter
+        type Converter interface {
+            // goverter:matchIgnoreCase a
+            ConvertString(source string) string
+        }
+error: '/ABSOLUTE/execution/input.go:4:1: type Converter: parsing method ConvertString: invalid goverter:matchIgnoreCase, parameters not supported'

scenario/7_error_match_ignore_case_err_path copy.yml

@@ -0,0 +1,42 @@
+input:
+    input.go: |
+        package structs
+
+        // goverter:converter
+        type Converter interface {
+            // goverter:matchIgnoreCase
+            Convert(source Input) Output
+        }
+
+        type Input struct {
+            NESTED InputNested
+        }
+        type InputNested struct {
+            Name string
+        }
+        type Output struct {
+            Nested OutputNested
+        }
+        type OutputNested struct {
+            Name int
+        }
+error: |-
+    Error while creating converter method:
+        func (github.com/jmattheis/goverter/execution.Converter).Convert(source github.com/jmattheis/goverter/execution.Input) github.com/jmattheis/goverter/execution.Output
+
+    | github.com/jmattheis/goverter/execution.Input
+    |
+    |      | github.com/jmattheis/goverter/execution.InputNested
+    |      |
+    |      |      | string
+    |      |      |
+    source.NESTED.Name
+    target.Nested.Name
+    |      |      |
+    |      |      | int
+    |      |
+    |      | github.com/jmattheis/goverter/execution.OutputNested
+    |
+    | github.com/jmattheis/goverter/execution.Output
+
+    TypeMismatch: Cannot convert string to int

scenario/7_error_match_ignore_case_unresolved_ambiguity.yml

@@ -0,0 +1,39 @@
+input:
+    input.go: |
+        package structs
+
+        // goverter:converter
+        type Converter interface {
+            // goverter:matchIgnoreCase
+            Convert(source Input) Output
+        }
+
+        type Input struct {
+            MyID string
+            MyId string
+        }
+        type Output struct {
+            Myid string
+        }
+error: |-
+    Error while creating converter method:
+        func (github.com/jmattheis/goverter/execution.Converter).Convert(source github.com/jmattheis/goverter/execution.Input) github.com/jmattheis/goverter/execution.Output
+
+    | github.com/jmattheis/goverter/execution.Input
+    |
+    |
+    |
+    source.???
+    target.Myid
+    |      |
+    |      | string
+    |
+    | github.com/jmattheis/goverter/execution.Output
+
+    Cannot match the target field with the source entry: multiple matches found for "Myid". Possible matches: MyID, MyId.
+
+    Explicitly define the mapping via goverter:map. Example:
+
+        goverter:map MyID Myid
+
+    See https://github.com/jmattheis/goverter#struct-field-mapping.

scenario/7_error_struct_missing_field.yml

@@ -29,4 +29,4 @@ error: |-
     |
     | github.com/jmattheis/goverter/execution.Output
 
-    Cannot set value for field Age because it does not exist on the source entry.
+    Cannot match the target field with the source entry: "Age" does not exist.

scenario/7_error_struct_missing_mapped_field.yml

@@ -30,4 +30,4 @@ error: |-
     |
     | github.com/jmattheis/goverter/execution.Output
 
-    Mapped source field 'Name3' doesn't exist.
+    Cannot find the mapped field on the source entry: "Name3" does not exist.

scenario/7_error_struct_missing_mapped_nested_field.yml

@@ -38,4 +38,4 @@ error: |-
     |
     | github.com/jmattheis/goverter/execution.Output
 
-    Mapped source field 'Name3' doesn't exist.
+    Cannot find the mapped field on the source entry: "Name3" does not exist.