Power Query: M expressions

Evaluating and inspecting M expressions, including with external sources. Terms are in the glossary.

Outside sources — session mode only

Parsing and evaluating an expression always work. But operations that pull data from outside — OData, a web source, a web connector, Postgres — require launching with the --session flag: the processor has no network of its own, and reaches out to the host for it. In one-shot mode they refuse honestly — more detail.

Operations on this page — 9

• evaluate_m_expression
• evaluate_m_expression_with_odata_feed
• evaluate_m_expression_with_sources
• evaluate_m_expression_with_web_connector
• evaluate_m_expression_with_web_source
• inspect_m_expression
• inspect_m_expression_with_odata_feed
• inspect_m_expression_with_postgres
• inspect_m_expression_with_sources

evaluate_m_expression

Evaluates an M expression.

Request

Field	TypeScript type	Req.
operation	"evaluate_m_expression"	yes
mText	string	yes
requestedBackend	ComputeBackendKind | null	no

Response on success · evaluate_m_expression

Field	TypeScript type	Req.
operation	"evaluate_m_expression"	yes
outcome	MExpressionOutcome	yes

Minimal JSON template

{
  "operation": "evaluate_m_expression",
  "mText": "<string>",
  "requestedBackend": "native-desktop"
}

evaluate_m_expression_with_odata_feed

Evaluates an M expression with an OData feed.

Request

Field	TypeScript type	Req.
operation	"evaluate_m_expression_with_odata_feed"	yes
mText	string	yes
connector	ApprovedODataFeedDescriptor	no
privacy	PqPrivacyEvaluationInput	no
requestedBackend	ComputeBackendKind | null	no

Response on success · evaluate_m_expression_with_odata_feed

Field	TypeScript type	Req.
operation	"evaluate_m_expression_with_odata_feed"	yes
outcome	MExpressionOutcome	yes

Minimal JSON template

{
  "operation": "evaluate_m_expression_with_odata_feed",
  "mText": "<string>",
  "requestedBackend": "native-desktop"
}

evaluate_m_expression_with_sources

Evaluates an M expression with sources.

Request

Field	TypeScript type	Req.
operation	"evaluate_m_expression_with_sources"	yes
mText	string	yes
sources	ApprovedSourceDescriptor[]	yes
privacy	PqPrivacyEvaluationInput	no
foldMode	"folding-on" | “force-local”	no
userStoreLevels	PqPrivacyLevelAssignment[]	no
subsetId	string	no
requestedBackend	ComputeBackendKind | null	no

Response on success · evaluate_m_expression_with_sources

Field	TypeScript type	Req.
operation	"evaluate_m_expression_with_sources"	yes
outcome	MExpressionOutcome	yes

Minimal JSON template

{
  "operation": "evaluate_m_expression_with_sources",
  "mText": "<string>",
  "sources": [],
  "requestedBackend": "native-desktop"
}

evaluate_m_expression_with_web_connector

Evaluates an M expression with a web connector.

Request

Field	TypeScript type	Req.
operation	"evaluate_m_expression_with_web_connector"	yes
mText	string	yes
connector	ApprovedWebConnectorDescriptor	no
requestedBackend	ComputeBackendKind | null	no

Response on success · evaluate_m_expression_with_web_connector

Field	TypeScript type	Req.
operation	"evaluate_m_expression_with_web_connector"	yes
outcome	MExpressionOutcome	yes

Minimal JSON template

{
  "operation": "evaluate_m_expression_with_web_connector",
  "mText": "<string>",
  "requestedBackend": "native-desktop"
}

evaluate_m_expression_with_web_source

Evaluates an M expression with a web source.

Request

Field	TypeScript type	Req.
operation	"evaluate_m_expression_with_web_source"	yes
mText	string	yes
source	ApprovedWebSourceDescriptor	no
privacy	PqPrivacyEvaluationInput	no
requestedBackend	ComputeBackendKind | null	no

Response on success · evaluate_m_expression_with_web_source

Field	TypeScript type	Req.
operation	"evaluate_m_expression_with_web_source"	yes
outcome	MExpressionOutcome	yes

Minimal JSON template

{
  "operation": "evaluate_m_expression_with_web_source",
  "mText": "<string>",
  "requestedBackend": "native-desktop"
}

inspect_m_expression

Inspects an M expression.

Request

Field	TypeScript type	Req.
operation	"inspect_m_expression"	yes
mText	string	yes
requestedBackend	ComputeBackendKind | null	no

Response on success · inspect_m_expression

Field	TypeScript type	Req.
operation	"inspect_m_expression"	yes
snapshot	PowerQueryInspectorSnapshot	yes

Minimal JSON template

{
  "operation": "inspect_m_expression",
  "mText": "<string>",
  "requestedBackend": "native-desktop"
}

inspect_m_expression_with_odata_feed

Inspects an M expression with an OData feed.

Request

Field	TypeScript type	Req.
operation	"inspect_m_expression_with_odata_feed"	yes
mText	string	yes
connector	ApprovedODataFeedDescriptor	no
requestedBackend	ComputeBackendKind | null	no

Response on success · inspect_m_expression_with_odata_feed

Field	TypeScript type	Req.
operation	"inspect_m_expression_with_odata_feed"	yes
snapshot	PowerQueryInspectorSnapshot	yes

Minimal JSON template

{
  "operation": "inspect_m_expression_with_odata_feed",
  "mText": "<string>",
  "requestedBackend": "native-desktop"
}

inspect_m_expression_with_postgres

Inspects an M expression with Postgres.

Request

Field	TypeScript type	Req.
operation	"inspect_m_expression_with_postgres"	yes
mText	string	yes
descriptor	PqPostgresDialogDescriptor	no
schema	string	no
item	string	no
connectUser	string	no
lanGrants	PqPostgresLanGrantWire[]	no
requestedBackend	ComputeBackendKind | null	no

Response on success · inspect_m_expression_with_postgres

Field	TypeScript type	Req.
operation	"inspect_m_expression_with_postgres"	yes
snapshot	PowerQueryInspectorSnapshot	yes

Minimal JSON template

{
  "operation": "inspect_m_expression_with_postgres",
  "mText": "<string>",
  "requestedBackend": "native-desktop"
}

inspect_m_expression_with_sources

Inspects an M expression with sources.

Request

Field	TypeScript type	Req.
operation	"inspect_m_expression_with_sources"	yes
mText	string	yes
sources	ApprovedSourceDescriptor[]	yes
requestedBackend	ComputeBackendKind | null	no

Response on success · inspect_m_expression_with_sources

Field	TypeScript type	Req.
operation	"inspect_m_expression_with_sources"	yes
snapshot	PowerQueryInspectorSnapshot	yes

Minimal JSON template

{
  "operation": "inspect_m_expression_with_sources",
  "mText": "<string>",
  "sources": [],
  "requestedBackend": "native-desktop"
}