hasura/graphql-engine · error · RelationshipError

No mapping for target command argument {argument_name} in th

Error message

No mapping for target command argument {argument_name} in the relationship {relationship_name} on type {type_name}

What it means

A command-based relationship does not provide a mapping for a target command argument that has no default and is not nullable/optional, so it cannot be satisfied at query time.

Source

Thrown at v3/crates/metadata-resolve/src/stages/object_relationships/error.rs:103

    #[error(
        "The target argument {argument_name} of model {model_name} has been mapped more than once in the relationship {relationship_name} on type {type_name}"
    )]
    ModelArgumentMappingExistsInRelationship {
        argument_name: ArgumentName,
        model_name: Qualified<ModelName>,
        relationship_name: RelationshipName,
        type_name: Qualified<CustomTypeName>,
    },
    #[error(
        "The target argument {argument_name} of command {command_name} has been mapped more than once in the relationship {relationship_name} on type {type_name}"
    )]
    CommandArgumentMappingExistsInRelationship {
        argument_name: ArgumentName,
        command_name: Qualified<CommandName>,
        relationship_name: RelationshipName,
        type_name: Qualified<CustomTypeName>,
    },
    #[error(
        "No mapping for target command argument {argument_name} in the relationship {relationship_name} on type {type_name}"
    )]
    MissingArgumentMappingInRelationship {
        type_name: Qualified<CustomTypeName>,
        argument_name: ArgumentName,
        relationship_name: RelationshipName,
    },
    #[error(
        "The target data connector {data_connector_name} for relationship {relationship_name} on type {type_name} does not support the variables capability"
    )]
    RelationshipTargetDoesNotSupportForEach {
        type_name: Qualified<CustomTypeName>,
        relationship_name: RelationshipName,
        data_connector_name: Qualified<DataConnectorName>,
    },
    #[error(
        "The target data connector {data_connector_name} for relationship {relationship_name} on type {type_name} has not defined any capabilities"
    )]

View on GitHub (pinned to 724551b9ae)

Solutions

1. Add an argument mapping (from a source field or value) for the missing command argument
2. Give the command argument a default value in the command metadata if it is genuinely optional
3. Remove the relationship if it is no longer meaningful

Example fix

// before
relationships:
  author:
    target: { command: AuthorById }  # command requires 'author_id'
// after
relationships:
  author:
    target: { command: AuthorById }
    argument_mappings:
      author_id: author_id

const required = commands[cmdName].arguments.filter(a => !a.has_default).map(a => a.name);
const mapped = new Set(Object.values(rel.argument_mappings ?? {}));
const missing = required.filter(a => !mapped.has(a));
if (missing.length) throw new Error(`missing mappings for command args: ${missing}`);

try { await applyMetadata(md); } catch (e) { if (/No mapping for target command argument/.test(e.message)) { /* map the named arg */ } throw e; }

When it happens

Trigger: Declaring a relationship to a command that requires arguments (e.g. `author_id`) without an argument mapping for each required argument.

Common situations: Adding a new required argument to a command and not updating relationships that call it; authoring a new relationship while missing some of the command's arguments.

Related errors

• target argument {argument_name} in argument mapping for rela
• The target argument {argument_name} of command {command_name
• unknown target command {command_name:} used in relationship
• target argument {argument_name} in argument mapping for rela
• The target argument {argument_name} of model {model_name} ha

AI-assisted analysis of hasura/graphql-engine@724551b9ae (2026-08-28). Data as JSON: /api/errors/232aea5bcca32201. Report an issue: GitHub.