schema-null-defaults skillA
schema-null-defaults is agent-read markdown (skill) from estuary/agent-skills: Handle NULL values and set default values for missing fields in collections and materializations. Use when fields need defaults, nullable primary key errors occur, or source data has gaps. Use when user says "NULL values", "default value", "missing field", "nullable primary key error", or "fill in missing data"..
Indexed from public GitHub and served as immutable, content-addressed versions. Install it pinned to an exact SHA-256 with the mdr CLI, and every file is verified against the hash recorded here before it reaches your agent. The deterministic audit below grades the latest version, and the same file always earns the same grade.
What the file says
# Handle NULLs and Default Values Handle NULL values and set default values for missing fields in materializations. **Docs:** https://docs.estuary.dev/concepts/schemas/#default-annotations ## When to Use - Need to provide default values for missing/optional fields - Handling nullable primary key errors in materializations (`cannot materialize collection with nullable key field unless it has a default value annotation`) - Ensuring consistent values when source data has gaps ## Prerequisites - Existing collection to modify - `flowctl` authenticated ## Key Concepts - `default` applies only to **missing** fields, not to explicit `null` values. A field present with `null` stays `null`. - `default` is read by materializations only — captures and derivations ignore it. Add defaults to the readSchema so auto-discover (which only touches writeSchema/connector-schema) can't overwrite them. ## Procedure ### Step 1: Pull Collection Specs ```bash flowctl catalog pull-specs --name <tenant>/<collection-name> ``` ### Step 2: Identify the Read Schema Find the read schema file (e.g., `collection.read.schema.yaml`). Typical structure for collections using schema inference: ```yaml …
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How to install
mdr add estuary/agent-skills/schema-null-defaults@git:20260707.049f6aemdr add estuary/agent-skills/schema-null-defaults@sha256:8614218ba148becePin to a label to follow the author's releases, or to a sha256 to freeze the exact bytes forever. Either way the resolved hash is written to mdr.lock, and mdr install reproduces it on any machine.
[](https://markdownregistry.com/a/art_acgc4xupityvzdns)
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Source
estuary/agent-skills · 7 stars · license Apache-2.0 · pushed 2026-09-17 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_acgc4xupityvzdns GET https://markdownregistry.com/api/v1/resolve?ref=estuary/agent-skills/schema-null-defaults GET https://markdownregistry.com/api/v1/blob/8614218ba148becec5f4353bf037d882271eae979f19922c24c5aa925765d594
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