QGIS/resources/function_help/json/get_feature

{
  "name": "get_feature",
  "type": "function",
  "groups": ["Record and Attributes"],
  "description": "Returns the first feature of a layer matching a given attribute value.",
  "variants": [{
    "variant": "Single value variant",
    "variant_description": "Along with the layer ID, a single column and value are specified.",
    "arguments": [{
      "arg": "layer",
      "description": "layer name or ID"
    }, {
      "arg": "attribute",
      "description": "attribute name to use for the match"
    }, {
      "arg": "value",
      "description": "attribute value to match"
    }],
    "examples": [{
      "expression": "get_feature('streets','name','main st')",
      "returns": "first feature found in \"streets\" layer with \"main st\" value in the \"name\" field"
    }]
  }, {
    "variant": "Map variant",
    "variant_description": "Along with the layer ID, a map containing the columns (key) and their respective value to be used.",
    "arguments": [{
      "arg": "layer",
      "description": "layer name or ID"
    }, {
      "arg": "attribute",
      "description": "Map containing the column and value pairs to use"
    }],
    "examples": [{
      "expression": "get_feature('streets',map('name','main st','lane_num','4'))",
      "returns": "first feature found in \"streets\" layer with \"main st\" value in the \"name\" field and  \"4\" value in the \"lane_num\" field"
    }]
  }],
  "tags": ["attribute", "first", "matching", "search", "find"]
}