fix: support array-based JSON syntax in WalkExpressions #422
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Adds support for JSON files with array-based root syntax like
[{"import": {...}}] which is used by Terraform 1.5+ for import
blocks. Previously, WalkExpressions would fail on these files
because JustAttributes() doesn't work with array-based JSON.
The fix implements a fallback mechanism that:
1. Tries JustAttributes() first (works for object-based JSON)
2. On failure, calls Content() to discover attribute names from
error diagnostics
3. Builds a schema with discovered attributes
4. Uses PartialContent() to extract proper json.expression objects
This ensures expressions pass json.IsJSONExpression() checks and
can be properly walked by rules.
Replaces error message parsing approach with direct JSON decoding using encoding/json. This is more reliable, faster, and cleaner. - Uses standard library to extract keys from JSON - Works for both object and array syntax - No string parsing or Content() call needed - All tests pass
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Fixes
WalkExpressionsto handle Terraform JSON files using array-based root syntax like[{"import": {...}}]. Previously these files would fail becauseJustAttributes()doesn't work with JSON arrays.Issue
Terraform JSON files can use either object-based syntax
{"resource": {...}}or array-based syntax[{"resource": {...}}]. TheWalkExpressionsmethod in the plugin SDK only supported object-based syntax.When processing array-based JSON files,
Body.JustAttributes()fails because HCL's JSON parser doesn't expose attributes at the array level. This causedWalkExpressionsto return errors and skip processing these files entirely.Closes terraform-linters/tflint#2279
Changes
WalkExpressionsto support array-based JSON syntax in addition to object-based syntaxextractJSONKeysfunction to parse JSON bytes withencoding/jsonand extract attribute names from both objects and arrays of objectsgetJSONAttributesfunction that falls back to schema-based extraction whenJustAttributes()failsJustAttributes()for backward compatibility with object-based JSONextractJSONKeysto discover attribute namesPartialContentto extract proper*json.expressionobjectsjson.IsJSONExpression()checks used by rulesTesting
resourceandvariableblocksReferences