# Writing Handlebars

> Write Handlebars template expressions for Celigo integrations -- dynamic values in mappings, HTTP bodies, SQL queries, URIs, and filters. Use when building any resource configuration that needs computed, conditional, or formatted field values.

- **Type:** Skill
- **Install:** `agentstack add skill-celigo-ai-writing-handlebars`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [celigo](https://agentstack.voostack.com/s/celigo)
- **Installs:** 0
- **Category:** [Databases](https://agentstack.voostack.com/c/databases)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [celigo](https://github.com/celigo)
- **Source:** https://github.com/celigo/ai/tree/main/skills/writing-handlebars

## Install

```sh
agentstack add skill-celigo-ai-writing-handlebars
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Writing Handlebars Expressions

Handlebars is Celigo's template language for embedding dynamic values into resource configurations. Any string field that the platform evaluates at runtime can contain Handlebars expressions.

Concerns when writing Handlebars:

- **Context** -- where the expression runs determines what data is available and how output is treated
- **Braces** -- double `{{ }}` vs triple `{{{ }}}` controls output escaping
- **Field access** -- `record.` prefix in all contexts (AFE 2.0), `@root` for job/settings/connection, bracket notation for special characters
- **Helpers** -- 79 custom helpers for math, string manipulation, dates, encoding, regex, and more
- **Block helpers** -- `#each`, `#if`, `#compare`, `#with` for iteration and conditional logic
- **Date/time** -- moment.js format tokens with timezone support

Used across exports, imports, mappings, output filters, and APIs.

## Where Handlebars Are Used

### Mapping extracts

In import `mappings[].extract` fields, Handlebars concatenates, transforms, or conditionally selects values. The context is the current record.

### HTTP request templates

Export and import `http` blocks use Handlebars in `relativeURI`, `body`, `headers`, and `postBody`. Triple braces are essential to avoid HTML encoding of query parameters and JSON.

### RDBMS SQL queries

SQL queries in `rdbms.query` use Handlebars with the mandatory `record.` prefix. Triple braces prevent encoding of SQL-significant characters like commas and quotes. For full SQL patterns (MERGE, upsert, bulk operations, dialect differences), see [writing-sql](../writing-sql/SKILL.md).

### Output filters

Expression-based filters on exports use Handlebars to evaluate whether a record passes through or gets skipped.

### File paths and names

Dynamic file names in FTP/S3 exports and imports use Handlebars for timestamps and record-derived values.

### Delta tokens

Platform-injected variables like `{{{lastExportDateTime}}}` provide the last successful export timestamp for incremental syncs. These are not record fields -- the platform injects them at runtime into the export's HTTP/query context only.

## Quick Reference

### Context Decision Matrix (AFE 2.0)

All contexts use `record.` prefix to access the current record's fields (AFE 2.0). Do NOT use bare field names, `data.field`, or `data.0.field` -- those are deprecated AFE 1.0 patterns. **Exception:** Mapper 1.0 (Salesforce/NetSuite) uses bare field names without `record.` prefix.

| Where | Syntax | Data prefix | Example |
|---|---|---|---|
| Mapping extract | `{{ }}` (double) | `record.` | `{{record.firstName}}` |
| HTTP relative URI | `{{{ }}}` (triple) | `record.` | `{{{record.orderId}}}` in URI |
| HTTP body / postBody | `{{{ }}}` (triple) | `record.` | `{{{record.orderId}}}` in JSON body |
| SQL query (RDBMS) | `{{{ }}}` (triple) | `record.` | `{{{record.email}}}` in WHERE clause |
| Output filter | `{{ }}` (double) | `record.` | `{{record.status}}` |
| Delta URI parameter | `{{{ }}}` (triple) | (platform-injected) | `{{{lastExportDateTime}}}` |

Additional context objects available via `@root`:

| Object | Description |
|--------|-------------|
| `record` | Current record being processed |
| `job` | Current job metadata |
| `settings` | Integration/flow settings |
| `connection` | Connection object (for auth headers) |

When **one-to-many grouping** is configured, the data shape changes to `batch_of_records` -- iterate with `{{#each batch_of_records}}` to access individual records.

### Key Syntax

- **`{{{triple-braces}}}`** -- raw output, no escaping. Use for URIs, SQL, JSON bodies, file paths -- anywhere commas, quotes, or ampersands matter. **In RDBMS**, triple braces output the raw value (`value`); double braces wrap in single quotes (`'value'`). Prefer triple and add literal quotes explicitly where needed.
- **`{{double-braces}}`** -- context-dependent formatting. In RDBMS adds single quotes around the value. In URLs, URL-encodes. Use triple braces for explicit control.
- **Always use `record.` prefix (AFE 2.0)** -- `{{{record.fieldName}}}` in all contexts, never bare `{{{fieldName}}}` or `{{{data.fieldName}}}` (AFE 1.0). Nested fields: `{{{record.properties.email}}}`.
- **Exception: Mapper 1.0 (Salesforce/NetSuite)** -- uses bare field names without `record.` prefix. This is the only context where bare field references are correct.

## Related Skills

- [configuring-exports > Quick Reference](../configuring-exports/SKILL.md#quick-reference) -- export adaptor types, delta sync setup, output filters
- [configuring-imports > Quick Reference](../configuring-imports/SKILL.md#quick-reference) -- import adaptor types, operation modes, mapping systems
- [writing-mappings > Quick Reference](../writing-mappings/SKILL.md#quick-reference) -- Mapper 2.0 fields, lookups, conditional mappings

## Syntax Fundamentals

### Braces

| Syntax | Behavior | When to use |
|--------|----------|-------------|
| `{{ }}` | Context-dependent formatting -- RDBMS wraps value in single quotes (`'value'`), URLs get URL-encoded | Use only when auto-formatting is desired |
| `{{{ }}}` | Raw output, no escaping or wrapping | Prefer everywhere -- SQL, JSON bodies, URIs, file paths. Add literal quotes yourself where needed |
| `{{{{ }}}}` | Raw block -- contents treated as literal string | Escaping Handlebars syntax itself |

### Field access

| Pattern | Meaning |
|---------|---------|
| `record.fieldName` | Standard field reference -- all contexts (AFE 2.0) |
| `record.nested.field` | Dot-notation for nested objects |
| `record.[Field With Spaces]` | Bracket notation for special characters in field names |
| `record.items.[0].name` | Array index access |
| `@root.fieldName` | Root context -- escape nested `#each` scope |
| `../fieldName` | Parent context -- one level up from current `#each` |
| `this` | Current iteration element |
| `@index` / `@key` | Current array index / object key in `#each` |
| `@first` / `@last` | Boolean -- first/last element in `#each` iteration |

### Subexpressions (nesting helpers)

Use `()` to nest one helper's output as input to another. The inner helper evaluates first:

```
{{uppercase (split record.fullName " " 0)}}              -- split then uppercase the first word
{{{base64Encode (join ":" record.user record.pass)}}}    -- join then encode
{{#compare (add record.qty 1) ">" "100"}}...{{/compare}} -- add then compare
{{#each (after record.tags 3)}}...{{/each}}              -- slice then iterate
```

Subexpressions can be nested multiple levels deep. Each `()` resolves inside-out.

### Block helpers

- `{{#each record.items}}...{{/each}}` -- iterate array or object
- `{{#if record.active}}...{{else}}...{{/if}}` -- conditional
- `{{#compare val1 "==" val2}}...{{/compare}}` -- comparison (`==`, `===`, `!=`, `!==`, ``, `=`)
- `{{#with record.address}}...{{/with}}` -- change context scope

### Date/time formatting

Uses moment.js tokens. Always use triple braces for date output.

Common tokens: `YYYY` (4-digit year), `MM` (2-digit month), `DD` (2-digit day), `HH` (24h hour), `mm` (minute), `ss` (second), `SSS` (millisecond), `Z` (timezone offset), `X` (Unix seconds), `x` (Unix milliseconds).

Timezone: pass as third argument -- `{{{dateFormat "YYYY-MM-DD" record.date "US/Eastern"}}}`.

### Date arithmetic

`dateAdd` works in **milliseconds**:
- 1 hour = 3,600,000
- 1 day = 86,400,000
- 7 days = 604,800,000

## Runtime Context at Each Stage

What `{{record.X}}` or `{{settings.Y}}` actually resolves to depends on **which bubble** the expression runs in. The shapes below were captured by setting `body: "{{{jsonSerialize this}}}"` on import/lookup bubbles and echoing through a mirror endpoint — they represent exactly what's available at runtime.

### Import bubble (HTTPImport, NetSuiteDistributedImport, etc.)

Body templates and Handlebars in `mappings[].extract` run per-record with this context:

```
{
  "0": { ...the record at batch index 0, with mapped fields... },   // per-record
  "data": [ ...array of all records in this page, post-mapping... ],
  "lookup": { ...merged results from preceding lookup steps... },
  "recordLookupError": null | { ... },                               // set when a lookup failed
  "settings": { "import": {...}, "connection": {...} },
  "connection": { /* FULL connection object: auth, baseURI, etc. */ },
  "import": { /* full import config */ },
  "job": { "parentJob": { "_id", "type", "startedAt", ... } },
  "templateVersion": 1,
  "testMode": false
}
```

### Lookup bubble (HTTPExport with `isLookup: true`)

Lookup request templates run per-record with a **different** shape:

```
{
  "exportStartTime": "ISO timestamp",
  "settings": { "export": {...}, "connection": {...} },
  "connection": { /* full connection object */ },

  // the record is spread at TOP LEVEL (not indexed by `0` like imports)
  "_id": "...",
  "name": "...",
  "": "...",

  "data": {
    /* copy of the record */,
    "_INITDATA": { /* original record before transforms */ }
  }
}
```

### Export bubble (source generator)

Export URI templates and delta tokens have a minimal context — the platform injects `{{{lastExportDateTime}}}`, `{{{currentExportDateTime}}}`, plus `settings` and `connection`. No `record.` context exists yet (records haven't been fetched).

### Key differences between import and lookup contexts

| Context key | Import | Lookup |
|---|---|---|
| Record location | `0.` + `data[].` | `` (top-level) + `data.` |
| `data` shape | array of records | single record (with `_INITDATA` nested) |
| `exportStartTime` | No | Yes |
| `lookup` | Yes (merged preceding results) | N/A |
| `import` / `job` / `recordLookupError` / `testMode` | Yes | No |
| `connection` (full) | Yes | Yes |

### How to rediscover the shape for any bubble

Set the body on an HTTP import or lookup to `{{{jsonSerialize this}}}` and point it at an echo endpoint (integrator.io's `/v1/mirror` works). Enable flow execution logging, run the flow, and inspect the `apiCall.response.body` — it's a copy of what you sent, which is the full runtime context. This works for any bubble whose adaptor sends an HTTP body.

## How to Write a Handlebars Expression

### 1. Identify the context

Where the expression runs determines what data is available. In AFE 2.0, all contexts use `record.` to access the current record:

| Context | Available data | Prefix |
|---------|---------------|--------|
| Mapping extract | Current record | `record.` |
| HTTP body/URI | Current record | `record.` |
| RDBMS query | Current record | `record.` |
| Output filter | Current record | `record.` |
| Delta URI parameter | Platform variables | `lastExportDateTime`, `lastExportDateTimeUTC` |

Other context objects (`job`, `settings`, `connection`) are accessible via `@root` -- e.g., `{{@root.connection.http.encrypted.apiKey}}`.

When one-to-many grouping is active, the shape is `batch_of_records` and you must iterate: `{{#each batch_of_records}}{{record.field}}{{/each}}`.

### 2. Know the data shape

Before writing any expression, inspect what the input data looks like:

```bash
# Test-run an export to see actual record shapes
celigo exports invoke 

# Check mock output for the expected shape
celigo --jq '.mockOutput' exports get 
```

### 3. Choose the right braces

- Default to `{{{ }}}` (triple) for HTTP bodies, SQL, URIs, file paths
- Use `{{ }}` (double) only in mapping extracts and display text where HTML escaping is acceptable
- When in doubt, use triple -- raw output never breaks SQL or JSON; HTML-escaped output can

### 4. Find the right helper

See the [helper index](references/helpers/helper-index.md) for all 79 custom helpers. Key categories:

- **[Math](references/helpers/math.md)** -- `abs`, `add`, `subtract`, `multiply`, `divide`, `modulo`, `ceil`, `floor`, `round`, `sum`, `avg`, `random`, `toFixed`, `toExponential`, `toPrecision`
- **[String](references/helpers/string.md)** -- `uppercase`, `lowercase`, `capitalize`, `capitalizeAll`, `camelcase`, `pascalcase`, `snakecase`, `dashcase`, `dotcase`, `pathcase`, `sentence`, `trim`, `trimLeft`, `trimRight`, `padLeft`, `padRight`, `replace`, `replacefirst`, `removefirst`, `chop`, `truncateWords`, `sanitize`, `split`, `join`, `reverse`, `occurrences`, `substring`
- **[Array](references/helpers/array.md)** -- `after`, `before`, `first`, `last`, `reverse`, `sort`, `unique`, `pluck`, `arrayify`, `lookup`, `getValue`, `sum`
- **[Date/time](references/helpers/date.md)** -- `dateFormat`, `dateAdd`, `timestamp`
- **[Encoding](references/helpers/encoding.md)** -- `base64Encode`, `base64Decode`, `htmlEncode`, `htmlDecode`, `jsonEncode`, `jsonParse`, `jsonSerialize`, `encodeURI`, `decodeURI`, `stripProtocol`, `stripQuerystring`
- **[Regex](references/helpers/regex.md)** -- `regexMatch`, `regexReplace`, `regexSearch`
- **[Auth/crypto](references/helpers/auth.md)** -- `hash`, `hmac`, `aws4`
- **[Type/logic](references/helpers/type-logic.md)** -- `typeOf`, `eq`, `isTruthy`, `isFalsey`, `hasOwn`, `hasNoItems`, `compare`
- **[Format](references/helpers/format.md)** -- `addCommas`, `bytes`, `ordinalize`
- **[Block helpers](references/helpers/block-helpers.md)** -- `#each`, `#if`, `#compare`, `#contains`, `#filter`, `#and`, `#or`, `#not`, `#unless`, `#with`, `#some`, `#startsWith`, `#inArray`, `#isEmpty`

### 5. Test the expression

```bash
# Invoke export to see if dynamic URI/query produces results
celigo exports invoke 

# Invoke import to validate body template renders correctly
celigo imports invoke 
```

## Common Patterns

### JSON comma separation in HTTP body templates

Avoid trailing commas when building JSON arrays:

```
{{#each record.items}}{...}{{#if @last}}{{else}},{{/if}}{{/each}}
```

### Grouped data access (one-to-many / batch_of_records)

When one-to-many grouping is configured, the data shape becomes `batch_of_records`. Iterate to access individual records:

```
{{#each batch_of_records}}
  {{record.orderId}}
  {{record.[Shipping City]}}
{{/each}}
```

### Conditional field with fallback

```
{{#if record.nickname}}{{{record.nickname}}}{{else}}{{{record.firstName}}}{{/if}}
```

### Nested iteration with parent context

```
{{#each record.orders}}
  Order: {{{this.id}}}  Customer: {{{../customerName}}}
  {{#each this.items}}
    Item: {{{this.sku}}}
  {{/each}}
{{/each}}
```

### SQL IN clause from list variable

Build by a preSavePage hook (which can inject fields into the record), rendered with triple braces:

```
SELECT id FROM orders WHERE status IN ({{{record.statusList}}})
```

### JavaScript-to-Handlebars equivalents

| JavaScript | Handlebars |
|-----------|------------|
| `str.split("?id=")[1]` | `{{split record.field "?id=" 1}}` |
| `str.replace("old", "new")` | `{{replace record.field "old" "new"}}` |
| `str.match(/pattern/)` | `{{{regexMatch record.field "pattern"}}}` |
| `Math.abs(n)` | `{{abs record.field}}` |
| `arr.length` | `{{record.items.length}}` |

## Pre-Submit Checklist

Before finalizing any Handlebars expression, verify each item:

- [ ] **Prefer triple braces `{{{ }}}`.** Double braces apply context-dependent formatting -- in RDBMS they wrap values in single quotes (`'value'`), in URLs they URL-encode. Use triple braces for explicit control and add literal quotes where needed.
- [ ] **`record.` prefix everywhere (AFE 2.0).** All contexts use `record.fieldName` -- mappings, HTTP bodies, SQL, filters. Never use bare `fieldName`, `data.fieldName`, or `data.0.fieldName` (AFE 1.0). Exception: Mapper 1.0 (Salesforce/NetSuite) uses bare field names.
- [ ] **`lastExportDateTime` only in export context.** This platform-injected variable is available in the export's HTTP/query context for delta syncs only -- not in mappings or import templates.
- [ ] **`dateAdd` values in milliseconds.** 1 day = 86,400,000. Not seconds, not hours.
- [ ] **`#each` context shifts.** Inside `{{#each}}`, `this` is the current item. Use `../` for parent or `@root` for top-level fields.
- [ ] **Missing fields fail silently.**

…

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [celigo](https://github.com/celigo)
- **Source:** [celigo/ai](https://github.com/celigo/ai)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-celigo-ai-writing-handlebars
- Seller: https://agentstack.voostack.com/s/celigo
- Browse the marketplace: https://agentstack.voostack.com/browse

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