Constraints example.

examples/constraints/capital.csv

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+id,capital,url
+1," 39,00",http://www.test.com
+2,"23,00",http://www.test.de
+3,"36,00",http://www.test.uk
+4,"20,00",http://www.test.co.il

examples/constraints/main.go

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+package main
+
+import (
+	"log"
+
+	"github.com/frictionlessdata/tableschema-go/csv"
+	"github.com/frictionlessdata/tableschema-go/schema"
+)
+
+// Example of how to read, validate and change a schema.
+func main() {
+	// Reading schem.
+	capitalSchema, err := schema.LoadFromFile("schema.json")
+	if err != nil {
+		log.Fatal(err)
+	}
+	// Validate schema.
+	if err := capitalSchema.Validate(); err != nil {
+		log.Fatal(err)
+	}
+
+	// Printing schema fields names.
+	log.Println("Fields:")
+	for i, f := range capitalSchema.Fields {
+		log.Printf("%d - %s\n", i, f.Name)
+	}
+
+	// Working with schema fields.
+	if capitalSchema.HasField("Capital") {
+		log.Println("Field capital exists in schema")
+	} else {
+		log.Fatalf("Schema must have the field capital")
+	}
+	field, _ := capitalSchema.GetField("URL")
+	if field.TestString("http://new.url.com") {
+		value, err := field.Cast("http://new.url.com")
+		log.Printf("URL unmarshal to value: %v\n", value)
+		if err != nil {
+			log.Fatalf("Error casting value: %q", err)
+		}
+	} else {
+		log.Fatalf("Value http://new.url.com must fit in field capital.")
+	}
+
+	// Dealing with tabular data associated with the schema.
+	table, err := csv.NewTable(csv.FromFile("capital.csv"), csv.LoadHeaders())
+	var capitals = []struct {
+		ID      int
+		Capital float64
+		URL     string
+	}{}
+
+	if err := capitalSchema.CastTable(table, &capitals); err != nil {
+		log.Fatalf("Error casting table: %q", err)
+	}
+	log.Printf("Cast Table: %+v\n", capitals)
+}

examples/constraints/schema.json

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+{
+    "fields": [
+      {
+        "name": "ID",
+        "title": "",
+        "description": "",
+        "type": "integer",
+        "format": "default",
+        "constraints": {
+          "unique": true,
+          "required": true
+        }
+      },
+      {
+        "name": "Capital",
+        "title": "",
+        "description": "",
+        "bareNumber": false,
+        "decimalChar": ",",
+        "type": "number",
+        "constraints": {
+          "required" :true,
+          "minimum": "0"
+        }
+      },
+      {
+        "name": "URL",
+        "title": "",
+        "description": "",
+        "type": "string"
+      }
+    ]
+}