writing-mappings
Write field mappings and transforms in Celigo integrations. Covers Mapper 2.0 (imports), Transformation 2.0 (exports), lookups, response mapping, and Mapper 1.0 (NetSuite/Salesforce). Use when editing mappings[], transform{}, responseMapping, or lookup configurations.
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npx skills add celigo/ai --skill writing-mappings
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Writing Mappings and Transforms
Mappings and transforms are the data reshaping layer in Celigo integrations. They control how fields from one system translate into fields for another. Mappings are used across flows, APIs, and tools.
Mapping Systems
Four systems handle data reshaping:
Mapper 2.0 modern recursive field mapping on imports ( mappings[] array). Handles nested objects, arrays of any depth, lookups, conditionals, and date conversions. Default for new imports on all adaptor types except NetSuite and Salesforce
Mapper 1.0 legacy flat mapping on NetSuite and Salesforce imports ( mapping.fields[] / mapping.lists[] ). Body level and sublist fields in separate flat arrays. Also present on many older HTTP/FTP/RDBMS imports created before Mapper 2.0 existed
Transformation 2.0 rule based data reshaping on exports ( transform.expression.rulesTwoDotZero ). Uses the same Mapper 2.0 schema internally. Two modes: "create" (build new record from scratch) or "modify" (edit fields on existing record, unmapped fields pass through)
Response mapping simple extract/generate pairs that carry data from a lookup or import response back into the record ( responseMapping on flow pageProcessors[] ). Uses Transformation 1.0 syntax
Lookups are shared across all systems static key value maps or references to LookupCache resources for large/dynamic datasets. NetSuite imports use a distinct lookup system that queries live NetSuite records.
Direction decides the tool. Mappings translate data going out to a destination every import needs them, because the in flight record almost never matches what the destination expects. Transformations reshape data coming in on exports, listeners, and API/tool entry stages. Never use an upstream transformation to match a destination's shape; that's the destination import's mapping. Transformations earn their keep in two situations: multiple sources feeding one pipeline (reshape each new source to the canonical record shape the existing steps expect) and genuinely messy source data (flatten deep nesting once at entry instead of fighting it in every downstream mapping). With a single well shaped source, don't add a transform just because you can and skip identity transforms that rename nothing.
Quick Reference
Which Mapping System?
Context System Syntax Read schema
Import field mapping (HTTP, RDBMS, FTP, S3, etc.) Mapper 2.0 mappings[] [mappings.yml](references/schemas/mappings.yml)
NetSuite/Salesforce import Mapper 1.0 mapping.fields[] see import schema ([netsuitedistributed.yml](../configuring imports/references/schemas/netsuitedistributed.yml), [salesforce.yml](../configuring imports/references/schemas/salesforce.yml))
Export data reshaping Transformation 2.0 transform{} [transform.yml](references/schemas/transform.yml)
Response mapping (lookup/import carry back) Transformation 1.0 extract/generate pairs [response mapping.yml](references/schemas/response mapping.yml)
Value translation Lookups lookups[] [lookups.yml](references/schemas/lookups.yml)
Editing existing imports: Many existing imports use Mapper 1.0 even for HTTP and RDBMS adaptor types (pre dating Mapper 2.0). Always check whether an import uses mappings[] (2.0) or mapping.fields[] (1.0) before modifying never mix the two.
Schema Index
Schema Contents
[mappings.yml](references/schemas/mappings.yml) Mapper 2.0 field definitions (generate, extract, dataType, buildArrayHelper, conditionals)
[lookups.yml](references/schemas/lookups.yml) Static and dynamic lookup definitions
[transform.yml](references/schemas/transform.yml) Transformation 2.0 envelope (mode, expression, script)
[response mapping.yml](references/schemas/response mapping.yml) Transformation 1.0 extract/generate pairs for response carry back
[netsuitedistributed.yml](../configuring imports/references/schemas/netsuitedistributed.yml) NetSuite Mapper 1.0 mapping + lookups
[salesforce.yml](../configuring imports/references/schemas/salesforce.yml) Salesforce Mapper 1.0 mapping
Related Skills
[configuring imports Quick Reference](../configuring imports/SKILL.md quick reference) import adaptor types, operation logic, hooks
[configuring exports Quick Reference](../configuring exports/SKILL.md quick reference) export adaptor types, delta syncs, webhooks
[writing handlebars Quick Reference](../writing handlebars/SKILL.md quick reference) Handlebars expressions used inside mapping extract fields
[building flows How to Build a Flow](../building flows/SKILL.md how to build a flow) wiring exports and imports into a flow pipeline
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Mapper 2.0 Workflow
The mappings[] array is recursive a mapping can contain nested child mappings of the same structure to any depth. This is the core design principle.
1. Check the existing resource
Before modifying mappings, always retrieve the current state of the resource. Check whether it uses Mapper 2.0 ( mappings[] ) or Mapper 1.0 ( mapping.fields[] ).
2. Understand the source data shape
Invoke the upstream export to see real records, or query the source system's metadata for the full field list.
3. Understand the target data shape
Query metadata for the target system to discover required fields and types.
4. Choose the input context
The input context controls what data is available to extract paths. Set via the "Input context" dropdown in the mapper UI:
record (default) extract paths reference the record directly. $.user id accesses the user id field on the record
envelope extract paths reference a wrapper object containing record , job , settings (with connection , flow , integration , flowGrouping ), iClient , and import . Record fields shift to $.record.user id , but you gain access to metadata like $.settings.connection.api username , $.job.type , $.settings.flow.fieldName
When to use envelope: APIs and tools where you need request context (headers, path params, query params, connection settings) directly in mappings without Handlebars. Also useful on transforms at the beginning of API/tool steps where the envelope exposes the full request context. Envelope context eliminates the need for {{settings.connection.fieldName}} Handlebars expressions use $.settings.connection.fieldName instead.
5. Map by data type
Every mapping needs three properties: generate (target field name), dataType (output type), and extract (how to get data from source).
Extract supports three patterns (distinguished by syntax):
JSON path starts with $. (e.g., $.customer.email ). Always references the top level root, even in nested mappings
Handlebars contains {{ (e.g., {{record.firstName}} {{record.lastName}} ). For computed values
Hard coded plain string literal (e.g., "Active" , "USD" ). Neither $. prefix nor {{
Simple types (string, number, boolean, date) direct field to field mapping. For dates, set extractDateFormat / generateDateFormat for conversion.
Objects set dataType: "object" , add child mappings in the mappings[] array. Never use dot notation in generate .
Arrays set dataType to an array type ( stringarray , numberarray , booleanarray , objectarray , arrayarray ) and configure buildArrayHelper[] . Three patterns for object arrays:
Extract only pull existing objects from source ( extract: "$.items[ ]" )
Mappings only construct objects from individual fields (each buildArrayHelper entry creates one array element)
Extract + mappings iterate a source array and reshape each element. Uses the composite object mechanism : array brackets [ ] in the extract path collapse to single objects inside the mappings, so $.orders[ ].items[ ] becomes $.orders.items.fieldName in child extract paths. Parent context remains accessible (e.g., $.orders.id , $.customerName )
6. Add lookups for value translation
Define lookups alongside mappings and reference them by name via lookupName on any mapping.
Static map object with key value pairs. Best for small, fixed sets (country codes, status values)
Dynamic lookupCacheId referencing a LookupCache resource, with optional extract JSON path to pull a specific field from the cached object
Set allowFailures: true + default to continue processing when lookup keys are missing
7. Add conditionals where needed
Control when a mapping applies: record created (only on insert), record updated (only on update), or extract not empty (skip when source is null/empty).
Schema reference
All Mapper 2.0 field definitions: [mappings.yml](references/schemas/mappings.yml), [lookups.yml](references/schemas/lookups.yml)
Transformation 2.0 Workflow
Transformation 2.0 reshapes data on exports before it enters the pipeline. It wraps Mapper 2.0 syntax in a transform envelope with a mode selector.
1. Check the existing resource
Before modifying transforms, retrieve the current export to inspect any existing transform configuration.
2. Choose the mode
create build a completely new record. Only mapped fields appear in output. Use when the output structure differs significantly from the source
modify edit specific fields on the existing record. Unmapped fields pass through unchanged. Use for surgical adjustments (rename, add, remove a few fields)
3. Write the mappings
Same Mapper 2.0 syntax: generate , dataType , extract , nested mappings , buildArrayHelper , lookups. Everything described in the Mapper 2.0 section above applies here, including input context.
Input context is especially valuable on transforms for APIs and tools set it to envelope to access the full request context (headers, path params, query params, connection settings) directly via JSON path instead of Handlebars.
4. Configure the transform envelope
Set transform.type: "expression" , expression.version: "2" , then place mappings[] and lookups[] under expression.rulesTwoDotZero with the chosen mode .
Script alternative: Set transform.type: "script" with script. scriptId and script.function for programmatic transforms when expression rules aren't sufficient.
Schema reference
All Transformation 2.0 field definitions: [transform.yml](references/schemas/transform.yml), [mappings.yml](references/schemas/mappings.yml), [lookups.yml](references/schemas/lookups.yml)
Mapper 1.0 Reference (NetSuite and Salesforce)
NetSuite and Salesforce imports use the older flat mapping structure. Two arrays within the mapping object:
mapping.fields[] body level field mappings. Each entry has extract (source path) or hardCodedValue (static value), generate (target field ID), and optional lookupName , dataType , internalId , immutable , discardIfEmpty , conditional
mapping.lists[] sublist/line item mappings. Each entry has generate (sublist ID, e.g., "item" ), jsonPath (source array path), and fields[] (column mappings with the same properties as body fields, plus isKey for matching existing lines)
NetSuite lookups are different they query live NetSuite records using recordType , searchField , resultField , and operator . Not static maps. Defined in netsuite da.lookups[] , referenced by lookupName in field mappings. To discover valid field IDs for searchField and resultField , run celigo metadata fields <connectionId <recordType — the returned field IDs are the exact values to use.
Salesforce lookups follow the same Mapper 1.0 pattern but the lookup structure is simpler.
Sublist field discovery: For NetSuite mapping.lists[].generate , the sublist name (e.g., "item" , "addressbook" ) comes from celigo metadata fields <connectionId <recordType — sublists appear as field groups. For Salesforce related