ConstraintString type appeared in graphql schema on the client

ConstraintString leaked through introspection. Is it by design? This makes GraphiQL unhappy.

Error: Invalid or incomplete schema, unknown type: ConstraintString. Ensure that a full introspection query is used in order to build a client schema.

ConstraintString can be revealed by the following query:

query Introspection { 
  __schema {
    types {
      name
      inputFields {
        type {
          name
        }
      }
    }
  }
}

[padenj]

I ran across this issue trying to solve a similar issue in a custom directive I created. My situation was slightly different, but I came up with a solution that could work for this issue as well. It would require an update to the directive and I’m not sure how/if it would affect non-Apollo users.

The issue is that a new type is being created in the directive schema visitor, but the type is not being added to the schema type map. For example, https://github.com/confuser/graphql-constraint-directive/blob/master/index.js#L54. If the type is not added to the schema type map, then the above mentioned error “Incomplete or Invalid schema…” will occur when Playground introspects the schema.

The following could be a possible solution. This example could be simplified since the new type is known to be either ConstraintStringType or ConstraintNumberType, but I left it a bit more generic for anyone else who might run across this issue. Note, isNamedType and isWrappingType is imported from ‘graphql’.

A possible solution could be to modify the wrapType function:

wrapType (field) {
    const fieldName = field.astNode.name.value
    if (field.type instanceof GraphQLNonNull && field.type.ofType === GraphQLString) {
      field.type = new GraphQLNonNull(new ConstraintStringType(fieldName, field.type.ofType, this.args))
    } else if (field.type === GraphQLString) {
      field.type = new ConstraintStringType(fieldName, field.type, this.args)
    } else if (field.type instanceof GraphQLNonNull && (field.type.ofType === GraphQLFloat || field.type.ofType === GraphQLInt)) {
      field.type = new GraphQLNonNull(new ConstraintNumberType(fieldName, field.type.ofType, this.args))
    } else if (field.type === GraphQLFloat || field.type === GraphQLInt) {
      field.type = new ConstraintNumberType(fieldName, field.type, this.args)
    } else {
      throw new Error(`Not a scalar type: ${field.type}`)
    }

   const typeMap = this.schema.getTypeMap();
   let type = field.type;

    if (isWrappingType(type)) {
           type = type.ofType;
    }

    if (isNamedType(type) && !typeMap[type.name]) {
          typeMap[type.name] = type;
    }
  }

[koresar]

UPD: ignore the below. The directive stopped working. 😃 UPD2: If you’d remove the two scalars below it will make the directive work, but will break client side retrospection. So, choose your destiny. 😃

---

I found a workaround! Omg, took a while.

Add this to your .graphql schema file (if you have one though):

# Current implementation on graphql-import does not support directives declared outside of the scehma (in node.js code).
# We have to redeclare each directive and type for now.
directive @constraint(
    # String constraints
    minLength: Int
    maxLength: Int
    startsWith: String
    endsWith: String
    notContains: String
    pattern: String
    format: String

    # Number constraints
    min: Int
    max: Int
    exclusiveMin: Int
    exclusiveMax: Int
    multipleOf: Int
) on INPUT_FIELD_DEFINITION

scalar ConstraintString

scalar ConstraintNumber