# Panel Go Field Resolver

> Create dynamic field configurations for Panel.go admin resources with validation, display options, and relationship handling. Use when adding fields to resources, configuring forms, or setting up field validation. Use when this capability is needed.

- Skill: `tomevault-io/panel-go-field-resolver` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/panel-go-field-resolver`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/panel-go-field-resolver/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/panel-go-field-resolver

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# Panel.go Field Resolver Expert

Expert in creating dynamic field configurations for Panel.go admin resources with validation, display options, and relationship handling.

## Expertise

You are a Panel.go field resolver expert. You understand:

- **Field Types**: Text, Number, Email, Image, Select, Date, Relationship fields (31 types)
- **Field Configuration**: Required, Unique, Searchable, ReadOnly, Nullable
- **Display Options**: OnList, OnDetail, OnForm, OnlyOnDetail, OnlyOnForm
- **Validation**: Built-in validators, custom validation rules
- **Relationships**: Link (BelongsTo), Detail (HasOne), Collection (HasMany), Connect (BelongsToMany)
- **Options**: Static options, dynamic options from database
- **File Uploads**: Image, Video, Audio, File fields with storage
- **Rich Content**: RichText, Code, Color, KeyValue fields

## Patterns

### Basic Field Resolver

```go
type {Name}FieldResolver struct{}

func (r *{Name}FieldResolver) ResolveFields(ctx *context.Context) []core.Element {
    return []core.Element{
        // Primary key
        fields.ID().ReadOnly().OnlyOnDetail(),

        // Text fields
        fields.Text("name").Required().Searchable(),
        fields.Email("email").Required().Unique(),
        fields.Textarea("description").Nullable(),

        // Number fields
        fields.Number("price").Required().Min(0),
        fields.Number("quantity").Default(0),

        // Select fields
        fields.Select("status").Options([]fields.Option{
            {Label: "Active", Value: "active"},
            {Label: "Inactive", Value: "inactive"},
        }).Default("active"),

        // Boolean
        fields.Switch("is_active").Default(true),

        // Date fields
        fields.Date("published_at").Nullable(),
        fields.DateTime("created_at").ReadOnly().OnlyOnDetail(),

        // Relationships
        fields.Link("user", &user.UserResource{}).DisplayKey("name"),
    }
}
```

### File Upload Fields

```go
fields.Image("avatar").
    Disk("public").
    Path("avatars").
    MaxSize(2048). // 2MB
    Accept("image/jpeg,image/png"),

fields.File("document").
    Disk("private").
    Path("documents").
    MaxSize(10240), // 10MB
```

### Relationship Fields

```go
// BelongsTo
fields.Link("category", &category.CategoryResource{}).
    DisplayKey("name").
    Searchable(),

// HasMany
fields.Collection("posts", &post.PostResource{}).
    DisplayKey("title"),

// BelongsToMany
fields.Connect("tags", &tag.TagResource{}).
    DisplayKey("name").
    Searchable(),
```

### Dynamic Options

```go
fields.Select("category_id").
    Options(func(ctx *context.Context) []fields.Option {
        var categories []domain.Category
        ctx.DB().Find(&categories)

        options := make([]fields.Option, len(categories))
        for i, cat := range categories {
            options[i] = fields.Option{
                Label: cat.Name,
                Value: cat.ID,
            }
        }
        return options
    }),
```

## Anti-Patterns

❌ **Don't expose sensitive fields** - Use ReadOnly() or hide completely
❌ **Don't skip validation** - Always validate required fields
❌ **Don't forget indexes** - Add Searchable() for indexed fields
❌ **Don't hardcode options** - Use dynamic options for database data
❌ **Don't ignore file size limits** - Set MaxSize() for uploads
❌ **Don't forget display keys** - Set DisplayKey() for relationships
❌ **Don't mix concerns** - Keep field logic in resolver, business logic in repository

## Decisions

### Field Naming
- **snake_case** for field names (matches database columns)
- **Descriptive names** that match domain model
- **Consistent naming** across resources

### Validation
- **Required** for non-nullable fields
- **Unique** for unique constraints
- **Min/Max** for number ranges
- **Custom validators** for complex rules

### Display
- **OnList** for table columns
- **OnDetail** for detail view
- **OnForm** for create/edit forms
- **OnlyOnDetail** for read-only info
- **OnlyOnForm** for input-only fields

## Sharp Edges

⚠️ **File Uploads**: Configure storage disk and path correctly
⚠️ **Relationships**: Use DisplayKey to show meaningful data
⚠️ **Options**: Cache dynamic options for performance
⚠️ **Validation**: Validate on both client and server
⚠️ **Searchable**: Only mark indexed fields as searchable
⚠️ **ReadOnly**: Use for computed or system fields
⚠️ **Nullable**: Match database schema nullability

## Usage

When user asks to add fields to a resource:

1. **Identify field types** based on data type
2. **Add validation** rules (Required, Unique, Min, Max)
3. **Configure display** options (OnList, OnDetail, OnForm)
4. **Add relationships** if needed
5. **Set defaults** for optional fields
6. **Configure file uploads** if needed
7. **Add searchable** for indexed fields

---
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<!-- tomevault:4.0:skill_md:2026-04-13 -->